REPUBLIC OF IRAQ MINISTRY OF ELECTRICITY STANDARD...

REPUBLIC OF IRAQ

MINISTRY OF ELECTRICITY

STANDARD SPECIFICATION

The Iraq Power Alliance worked in close cooperation with the Ministry of Electricity to produce a comprehensive set of standard specifications for use in the Iraq Power Supply Industry. The specifications were prepared between 2004 and 2006 for use by the Ministry in design, procurement, construction & commissioning and cover all major project types, areas of interest including, steam, gas turbine and diesel generating stations, high and medium voltage substations, overhead lines, together with ancillary transmission, distribution and control equipment. The specifications are generic and therefore require the addition of project specific information such as: the site location, layout and line routing plans; the ratings and numbers of generators; the ratings and numbers of transformers and switchgear circuits; project specific communications and SCADA requirements and any non-standard requirements that are project specific. The specifications have been drafted on the basis that such data will be defined by the Ministry in a Project Scope of Works and, when appropriate, the Ministry will add to or modify the general specifications and schedules to reflect the needs of a particular project. These standard specifications are based on the requirements of IEC and British Standards and were prepared in accordance with Ministry wishes and recommendations. The Iraq Power Alliance gratefully acknowledges the cooperation and guidance provided by the Ministry in the preparation of these specifications.

The Iraq Power Alliance is made up of Parsons Brinckerhoff and Worley Parson, both leading international engineering companies in the Power Supply Industry.

www.pbpower.net www.worleyparsons.com

http://www.pbpower.net/

http://www.worleyparsons.com/

MINISTRY OF ELECTRICITY IRAQ SUPERGRID PROJECTS 400/132 KV GIS SUBSTATIONS VOLUME 1 TECHNICAL SPECIFICATION SUBSTATION PLANT JANUARY 2007

400kV GIS SUBSTATION – VOLUME 1

LIST OF REVISIONS

Current Rev.

Date Page affected

Prepared by

Checked by (technical)

Checked by (quality

assurance)

Approved by

1 2 3 4 5

19.11.04 07.03.05 Aug 05 Oct 05 Jan 07

ALL ALL ALL ALL

SSA SSA/JK JK/MH MH/JK MH/JK

JW JW JW JW JW

JW JW JW JW JW

JW JW JW JW JW

REVISION HISTORY

2 07.03.05 ALL Re-assessment following production of 132 kV specification 3 Aug 05 ALL Updated with MOE comments and general alignment across

volumes. 4 Oct 05 ALL Specification split into GIS and AIS versions.

Capacitor specification rationalised. Impulse withstand and Power frequency withstand values reviewed in accordance with IEC 60694. Details for 11 kV (Tertiary) shunt reactors added.

5 Jan 07 ALL General review


CONTENT SHEET

VOLUME 1 TECHNICAL SPECIFICATION – PLANT VOLUME 2 TECHNICAL SPECIFICATION & SCHEDULES – CIVIL WORKS VOLUME 3 TECHNICAL SCHEDULES – PLANT


CONTENTS

Page No.

1. SYSTEM PERFORMANCE..............................................................................1-1

1.1 Topographical and Meteorological Site Conditions ..........................................1-1 1.2 Electrical Design Criteria ..................................................................................1-2 1.3 Insulation levels for equipment at site altitude..................................................1-2 1.4 Minimum Electrical Clearances in Air ...............................................................1-3 1.5 Structures .........................................................................................................1-3

1.5.1 Factors of Safety ..............................................................................................1-3 1.5.2 Switchgear Structure Stresses .........................................................................1-4

1.6 Switchgear Loadings ........................................................................................1-4 1.7 Electrical Station Services................................................................................1-4

2. GENERAL REQUIREMENTS ..........................................................................2-1

2.1 Intent and Nature of Work ................................................................................2-1 2.2 Standards and Codes.......................................................................................2-1 2.3 Abbreviations....................................................................................................2-2 2.4 Places of Manufacture......................................................................................2-3 2.5 Orders Issued to Subcontractors......................................................................2-3 2.6 Transport ..........................................................................................................2-3 2.7 Safety of personnel ..........................................................................................2-3 2.8 Compliance with regulations ............................................................................2-3 2.9 General particulars and guarantees .................................................................2-4 2.10 Planning and progress reports .........................................................................2-4 2.11 Quality assurance.............................................................................................2-5

2.11.1 Quality assurance requirements.......................................................................2-6 2.11.2 Quality assurance arrangements – quality plan ...............................................2-6 2.11.3 Monitoring by the Engineer ..............................................................................2-7 2.11.4 Contractor quality audits...................................................................................2-7 2.11.5 Control of subcontractors .................................................................................2-7 2.11.6 Inspection and tests .........................................................................................2-8 2.11.7 Construction/installation phase.......................................................................2-10 2.11.8 Non-conformances .........................................................................................2-10 2.11.9 Records ..........................................................................................................2-11 2.11.10 Method statements.........................................................................................2-11

2.12 Design and standardization............................................................................2-11 2.13 Quality of material ..........................................................................................2-12 2.14 Language, weights and measures .................................................................2-12 2.15 Erection, supervision and checking of work on site........................................2-13 2.16 Bolts and Nuts ................................................................................................2-13 2.17 Cleaning and Painting ....................................................................................2-14

2.17.1 Works Processes ...........................................................................................2-14 2.17.2 Site Painting ...................................................................................................2-15


2.18 Galvanizing.....................................................................................................2-15 2.19 Labels and Plates...........................................................................................2-16 2.20 Erection Marks ...............................................................................................2-17 2.21 Tropicalization ................................................................................................2-18 2.22 Relays, Switches, Fuses and Ancillary Equipment.........................................2-20 2.23 Auxiliary Wiring and Panel Boards .................................................................2-21 2.24 Earth Connection............................................................................................2-24 2.25 Terminal Boards .............................................................................................2-24 2.26 Special tools ...................................................................................................2-25 2.27 Interchangeability ...........................................................................................2-25 2.28 Spares ............................................................................................................2-25 2.29 Packing, Shipping and Storage ......................................................................2-26 2.30 Integral Electric Motors...................................................................................2-27

3. SWITCHGEAR - GENERAL.............................................................................3-1

3.1 Extent of Supply ...............................................................................................3-1 3.2 Substation Design ............................................................................................3-1 3.3 Current Rating & Temperature Limitations.......................................................3-1

4. GAS INSULATED SWITCHGEAR (GIS)..........................................................4-1

4.1 General.............................................................................................................4-1 4.2 Gas Insulated Switchgear (GIS) Enclosures ....................................................4-1 4.3 Gas Insulated Switchgear - Busbars and Connection Chambers ....................4-2 4.4 Enclosure Gas Zones.......................................................................................4-3 4.5 Expansion Joints and Flexible Connections.....................................................4-3 4.6 Future Extensions ............................................................................................4-3 4.7 Gas Monitoring and Handling...........................................................................4-3 4.8 Local Control Cubicles .....................................................................................4-4 4.9 Gas Insulated Bus Duct and Bushings.............................................................4-4 4.10 GIS HV Circuit Breakers (72.5 kV and Above) .................................................4-5

4.10.1 General.............................................................................................................4-5 4.10.2 Circuit Breaker Operating Mechanisms............................................................4-6

4.10.2.1 General.............................................................................................................4-6 4.10.2.2 Spring Mechanisms..........................................................................................4-7 4.10.2.3 Hydraulic and Hydraulic/Spring Mechanisms...................................................4-8 4.10.2.4 Mechanism Housings .......................................................................................4-8

4.11 GIS Disconnect Switches .................................................................................4-9 4.12 Earth Switches and Maintenance Earthing Devices.......................................4-10

4.12.1 GIS Earth Switches ........................................................................................4-10 4.12.2 Portable Maintenance Earthing Devices ........................................................4-11

4.13 Current Transformers .....................................................................................4-11

4.13.1 General...........................................................................................................4-11 4.13.2 GIS Current Transformers..............................................................................4-12 4.13.3 Current Transformer Primary Injection Tests .................................................4-13

4.14 Voltage Transformers in GIS Switchgear .......................................................4-13


4.14.1 General...........................................................................................................4-13 4.14.2 GIS Voltage Transformers..............................................................................4-14

4.15 Surge Arresters ..............................................................................................4-14

4.15.1 General...........................................................................................................4-14 4.15.2 Surge Counters ..............................................................................................4-14

4.16 Sulphur Hexafluoride Gas (SF6) .....................................................................4-15

4.16.1 General...........................................................................................................4-15 4.16.2 Gas Handling Equipment ...............................................................................4-15 4.16.3 Pipes and Couplings for the Connection of SF6 Gas.....................................4-16

4.17 Overhead Travelling Crane ............................................................................4-16

4.17.1 General...........................................................................................................4-16 4.17.2 Construction Features ....................................................................................4-16 4.17.3 Structure.........................................................................................................4-17 4.17.4 Crane Rails.....................................................................................................4-17 4.17.5 Crane Bridge ..................................................................................................4-17 4.17.6 Electrical Parts ...............................................................................................4-18 4.17.7 Motors ............................................................................................................4-18 4.17.8 Push Button Control Station ...........................................................................4-19 4.17.9 Overload Relays.............................................................................................4-19 4.17.10 Switchgear......................................................................................................4-19 4.17.11 Circuit Breaker Cabinets ................................................................................4-19 4.17.12 Limit Switches ................................................................................................4-19 4.17.13 Tools...............................................................................................................4-19

4.18 GIS Equipment Cable Facilities......................................................................4-20

4.18.1 Method of Termination of Cables ...................................................................4-20 4.18.2 Cable Test and Isolating Facilities..................................................................4-20

4.19 Interlocking Equipment ...................................................................................4-21

4.19.1 Extent of Supply .............................................................................................4-21 4.19.2 General...........................................................................................................4-21 4.19.3 400 kV Area....................................................................................................4-22 4.19.4 Transformers 400/132/11 kV..........................................................................4-22 4.19.5 132 kV Area....................................................................................................4-23 4.19.6 Tertiary Loads ................................................................................................4-23 4.19.7 Site Supplies ..................................................................................................4-23 4.19.8 DC Station Service .........................................................................................4-23 4.19.9 Miscellaneous Interlocks ................................................................................4-23 4.19.10 Locking Arrangements ...................................................................................4-23

5. AIR INSULATED SWITCHGEAR (AIS)............................................................5-1

5.1 Clearances .......................................................................................................5-1 5.2 Method of Line Termination..............................................................................5-1 5.3 Disconnect Switches ........................................................................................5-1 5.4 Current Transformers .......................................................................................5-2


5.4.1 General.............................................................................................................5-2 5.4.2 Air Insulated Current Transformers ..................................................................5-4 5.4.3 Current Transformer Primary Injection Tests ...................................................5-4

5.5 Voltage Transformers and Coupling Capacitors...............................................5-4

5.5.1 General.............................................................................................................5-4 5.5.2 Open Terminal Voltage Transformers and Coupling Capacitors......................5-5

5.5.2.1 Wound Type (Electromagnetic) Voltage Transformers ....................................5-5 5.5.2.2 Capacitor Type Voltage Transformers..............................................................5-6 5.5.2.3 Oil-Filled Voltage Transformers........................................................................5-7 5.5.2.4 SF6 Gas-Filled Voltage Transformers..............................................................5-7

5.6 Lightning (Surge) Arresters ..............................................................................5-7 5.7 Safety Screening of Equipment........................................................................5-8 5.8 Oil-Filled Chambers..........................................................................................5-8 5.9 Joints for Oil-Filled Chambers ..........................................................................5-9 5.10 Oil .....................................................................................................................5-9 5.11 Auxiliary Switches & Contactors.......................................................................5-9 5.12 Primary Equipment and Connections.............................................................5-10 5.13 Earthing Switches and Devices......................................................................5-10

5.13.1 400 kV System ...............................................................................................5-10 5.13.2 Operating Mechanisms ..................................................................................5-10 5.13.3 Maintenance Earths .......................................................................................5-10

5.14 Busbars, Insulators and Hardware .................................................................5-10

5.14.1 Extent of Supply .............................................................................................5-10 5.14.2 Busbars and Connections ..............................................................................5-11 5.14.3 Insulators........................................................................................................5-12

5.14.3.1 General...........................................................................................................5-12 5.14.3.2 Electrical Design of Insulators ........................................................................5-12 5.14.3.3 Mechanical Design of Insulators.....................................................................5-12 5.14.3.4 Marking of Insulators ......................................................................................5-13 5.14.3.5 Suspension and Tension Insulators ...............................................................5-13 5.14.3.6 Post-Type Insulators ......................................................................................5-13 5.14.3.7 Bushing-Type Insulators.................................................................................5-13

5.14.4 Clamps and Fittings........................................................................................5-14 5.14.5 Corona............................................................................................................5-15 5.14.6 Guard Rings or Arcing Horns .........................................................................5-15

5.15 Allowance for Damage, Breakage and Loss ..................................................5-15 5.16 Phase Identification ........................................................................................5-15 5.17 Junction Boxes and Kiosks ............................................................................5-16 5.18 Outdoor support structures and landing gantries ...........................................5-16 5.19 Interlocking Equipment ...................................................................................5-16

6. TRANSFORMERS AND REACTORS..............................................................6-1

6.1 Extent of Supply ...............................................................................................6-1


6.2 Reference documents ......................................................................................6-1 6.3 Type .................................................................................................................6-1 6.4 General.............................................................................................................6-2 6.5 Tertiary windings ..............................................................................................6-3 6.6 Loss Evaluation ................................................................................................6-3 6.7 Penalties...........................................................................................................6-4 6.8 Magnetic circuits...............................................................................................6-4 6.9 Windings...........................................................................................................6-5 6.10 Internal earthing arrangements ........................................................................6-5 6.11 Tanks................................................................................................................6-6 6.12 Bushings...........................................................................................................6-8

6.12.1 Oil/SF6 Bushings ..............................................................................................6-8

6.12.2 Oil/Air Bushings................................................................................................6-9 6.12.3 Terminations.....................................................................................................6-9

6.13 Conservator Vessels, Oil Level Gauges and Breathers .................................6-10 6.14 Valves.............................................................................................................6-11 6.15 Cooling Plant ..................................................................................................6-11 6.16 Cooler Control ................................................................................................6-13 6.17 On-load Tap Changing Equipment .................................................................6-13

6.17.1 Automatic and Manual Voltage Control ..........................................................6-16

6.18 Parallel operation ...........................................................................................6-18 6.19 Disconnecting and sealing end chambers......................................................6-19 6.20 Temperature indicating devices, alarms and gas and oil actuated relays ......6-19

6.20.1 Temperature Indicating Devices and Alarms..................................................6-19 6.20.2 Gas and Oil Actuated Relays .........................................................................6-20

6.21 Oil Flow Indicators..........................................................................................6-21 6.22 Current transformers ......................................................................................6-21 6.23 Surge protection .............................................................................................6-21 6.24 Condition Monitoring System..........................................................................6-21 6.25 Transformer Oil ..............................................................................................6-22 6.26 Topping Up with Oil and Drying out on Site....................................................6-22 6.27 Oil Handling and Test Equipment...................................................................6-23 6.28 Transformer Marshalling Kiosk.......................................................................6-23 6.29 400 kV Reactors.............................................................................................6-24

7. 11 KV TERTIARY COMPENSATING EQUIPMENT SWITCHGEAR AND CONNECTIONS...............................................................................................7-1

7.1 Extent of Supply ...............................................................................................7-1 7.2 General.............................................................................................................7-1 7.3 11 kV Switchgear .............................................................................................7-1

7.3.1 Degree of Protection ........................................................................................7-2 7.3.2 Current Ratings ................................................................................................7-2 7.3.3 Busbars and Connection ..................................................................................7-2 7.3.4 Circuit Breakers................................................................................................7-3 7.3.5 Operating Mechanism ......................................................................................7-3


7.3.6 Draw-out Mechanisms of Withdrawable Circuit Breakers ................................7-4 7.3.7 Interchangeability and Isolation of Circuit Breaker ...........................................7-5 7.3.8 Circuit Breaker Isolating Contacts ....................................................................7-5 7.3.9 Auxiliary Contacts.............................................................................................7-5 7.3.10 Service Life.......................................................................................................7-5 7.3.11 Fused Disconnect Switches .............................................................................7-5 7.3.12 11 kV Protection, Control, Indication and Alarms.............................................7-5 7.3.13 Interlocks ..........................................................................................................7-6

7.4 Earthing ............................................................................................................7-8

7.4.1 Main Earthing ...................................................................................................7-8 7.4.2 Temporary Earthing..........................................................................................7-9

7.5 Cable Terminations ..........................................................................................7-9 7.6 Voltage Transformers.......................................................................................7-9

7.6.1 Type, Ratio, Accuracy Class and Rating..........................................................7-9 7.6.2 Connections and Protection ...........................................................................7-10

7.7 Current Transformers .....................................................................................7-10

7.7.1 Type, Ratio, Accuracy Class and Rating........................................................7-11 7.7.2 Terminals and Connections............................................................................7-11

7.8 Station Service Transformers.........................................................................7-12 7.9 Earthing Transformers....................................................................................7-13

7.10 Capacitors and Series Reactor.......................................................................7-14

7.10.1 General...........................................................................................................7-14 7.10.2 Capacitors ......................................................................................................7-14 7.10.3 Containers ......................................................................................................7-14 7.10.4 Fuses..............................................................................................................7-15 7.10.5 Overvoltages and Overloads..........................................................................7-15 7.10.6 Discharge and Earthing Devices ....................................................................7-15 7.10.7 Duty Under Fault Conditions ..........................................................................7-16 7.10.8 Rating and Property Plates ............................................................................7-16 7.10.9 Racks for Unit Capacitors...............................................................................7-16 7.10.10 Assumed Working Loads ...............................................................................7-16 7.10.11 Construction ...................................................................................................7-17 7.10.12 Access and Interlocks ....................................................................................7-17 7.10.13 Rack Insulation...............................................................................................7-17 7.10.14 Terminals........................................................................................................7-17 7.10.15 Series Reactors..............................................................................................7-17

7.10.15.1 General...........................................................................................................7-17 7.10.15.2 Windings.........................................................................................................7-18

7.10.16 Earthing Arrangements. .................................................................................7-18 7.10.17 Surge Arresters ..............................................................................................7-18

7.11 11 kV (Tertiary) Shunt Reactors .....................................................................7-19


7.11.1 General...........................................................................................................7-19

8. CONTROL, INDICATION, METERING AND ANNUNCIATION .......................8-1

8.1 General Requirements .....................................................................................8-1

8.1.1 Extent of Supply ...............................................................................................8-1 8.1.2 Plant Control Strategy ......................................................................................8-1

8.1.2.1 Circuit Breaker Opening ...................................................................................8-1 8.1.2.2 Circuit Breaker Closing.....................................................................................8-2 8.1.2.3 Circuit Breaker Local/Remote Selection...........................................................8-2 8.1.2.4 Circuit Breaker Test/Normal Selection .............................................................8-3 8.1.2.5 Trip Circuit Supervision ....................................................................................8-3 8.1.2.6 Circuit Breaker Discrepancy Indication.............................................................8-3 8.1.2.7 Synchronising and Dead Line/Bar Check Interlocks ........................................8-3 8.1.2.8 Disconnect Switch Control ...............................................................................8-5 8.1.2.9 Disconnect Switch Annunciation ......................................................................8-6 8.1.2.10 Earth Switches .................................................................................................8-6 8.1.2.11 Transformer Tap Changer Control ...................................................................8-6

8.2 Station Metering ...............................................................................................8-6

8.2.1 System Voltage Local Indication (400 kV)........................................................8-6 8.2.2 System Voltage Local Indication (132 kV)........................................................8-6 8.2.3 400 kV System Frequency (Local Indication) ...................................................8-6 8.2.4 Voltage Recorder (Local Indication) .................................................................8-7 8.2.5 Station Totalising Metering (Local) ...................................................................8-7 8.2.6 Energy Meters ..................................................................................................8-7 8.2.7 Station Clocks ..................................................................................................8-7 8.2.8 Metering Transducers ......................................................................................8-7

8.3 SCS Specification.............................................................................................8-8

8.3.1 Introduction.......................................................................................................8-8 8.3.2 Design Principles..............................................................................................8-9 8.3.3 System Architecture .........................................................................................8-9 8.3.4 System Functions...........................................................................................8-10

8.3.4.1 General...........................................................................................................8-10 8.3.4.2 Commands .....................................................................................................8-11 8.3.4.3 Alarm and Indication Handling........................................................................8-12 8.3.4.4 Measured Value Lists .....................................................................................8-13 8.3.4.5 Supervisory Requirements (NCC)..................................................................8-13 8.3.4.6 Trends ............................................................................................................8-14 8.3.4.7 Data Logging ..................................................................................................8-14 8.3.4.8 Hand Dressing................................................................................................8-15 8.3.4.9 Operator Interface ..........................................................................................8-15 8.3.4.10 System Operating Points................................................................................8-16 8.3.4.11 Modes of Operation........................................................................................8-16

8.3.5 System Capacity ............................................................................................8-17 8.3.6 System Performance......................................................................................8-17 8.3.7 Software Requirements..................................................................................8-18


8.3.7.1 General...........................................................................................................8-18 8.3.7.2 Real-time database ........................................................................................8-18 8.3.7.3 Database management ..................................................................................8-18 8.3.7.4 Data processing .............................................................................................8-18

8.3.8 Hardware Requirements ................................................................................8-19

8.3.8.1 General...........................................................................................................8-19 8.3.8.2 Master Control Units.......................................................................................8-19 8.3.8.3 Remote Communications Interface ................................................................8-19 8.3.8.4 Bay Control Units ...........................................................................................8-20 8.3.8.5 Local Control Mimic ........................................................................................8-20 8.3.8.6 Digital Inputs...................................................................................................8-21 8.3.8.7 Analogue Inputs .............................................................................................8-21 8.3.8.8 Command Outputs .........................................................................................8-21 8.3.8.9 Pulse Counting Inputs ....................................................................................8-21 8.3.8.10 CT and VT Inputs ...........................................................................................8-21 8.3.8.11 Operator Workstations....................................................................................8-21 8.3.8.12 Printers ...........................................................................................................8-22 8.3.8.13 Local Area Network ........................................................................................8-23

8.3.9 Environmental Performance...........................................................................8-23

8.3.9.1 Atmospheric Environment ..............................................................................8-23 8.3.9.2 Mechanical Environment ................................................................................8-24 8.3.9.3 Electrical Environment....................................................................................8-24 8.3.9.4 Insulation ........................................................................................................8-24 8.3.9.5 Electromagnetic Compatibility ........................................................................8-25

8.3.10 Uninterruptible Power Supply.........................................................................8-25

8.3.10.1 Modes of Operation........................................................................................8-26 8.3.10.2 Mains Supply Failure......................................................................................8-26 8.3.10.3 Static By-Pass Switch ....................................................................................8-26 8.3.10.4 Manual Maintenance By-Pass........................................................................8-26 8.3.10.5 Control and Instrumentation ...........................................................................8-26

8.3.11 Maintenance and Spares ...............................................................................8-27 8.3.12 Documentation ...............................................................................................8-27 8.3.13 Training ..........................................................................................................8-28 8.3.14 Warranty and Support. ...................................................................................8-28

8.4 Facilities to be provided to the SCS for Substation and NCC ........................8-28

8.4.1 General...........................................................................................................8-28 8.4.2 Facility List......................................................................................................8-29

9. PROTECTION REQUIREMENTS....................................................................9-1

9.1 General.............................................................................................................9-1

9.1.1 Background ......................................................................................................9-1 9.1.2 Extent of Supply ...............................................................................................9-2 9.1.3 Discrimination...................................................................................................9-2


9.1.4 Objective Fault Clearance Times .....................................................................9-3 9.1.5 Protection System Construction and Mounting ................................................9-3 9.1.6 Indications ........................................................................................................9-4 9.1.7 Contacts ...........................................................................................................9-4 9.1.8 Numeric Relays ................................................................................................9-4 9.1.9 Trip Circuit Supplies .........................................................................................9-5

9.1.10 Trip Circuit Supervision and Auxiliary Supply Monitoring .................................9-5 9.1.11 Commissioning and Routine Testing Facilities.................................................9-6 9.1.12 Relay Settings ..................................................................................................9-6

9.2 Environmental Performance.............................................................................9-6

9.2.1 Atmospheric Environment ................................................................................9-6

9.2.1.1 Temperature.....................................................................................................9-6 9.2.1.2 Relative Humidity .............................................................................................9-7 9.2.1.3 Enclosure .........................................................................................................9-7

9.2.2 Mechanical Environment ..................................................................................9-7

9.2.2.1 Vibration ...........................................................................................................9-7 9.2.2.2 Shock and Bump ..............................................................................................9-7 9.2.2.3 Seismic.............................................................................................................9-7

9.2.3 Electrical Environment......................................................................................9-7

9.2.3.1 DC Auxiliary Energising Quantity .....................................................................9-7 9.2.3.2 Frequency ........................................................................................................9-8

9.2.4 Insulation ..........................................................................................................9-8

9.2.4.1 Rated Insulation Voltage ..................................................................................9-8 9.2.4.2 Dielectric tests ..................................................................................................9-8 9.2.4.3 Impulse voltage ................................................................................................9-8

9.2.5 Electromagnetic Compatibility ..........................................................................9-8

9.2.5.1 1 MHz Burst Disturbance..................................................................................9-8 9.2.5.2 Electrostatic Discharge.....................................................................................9-8 9.2.5.3 Radiated Electromagnetic Field Disturbance ...................................................9-8 9.2.5.4 Fast Transient Disturbance ..............................................................................9-8 9.2.5.5 Electromagnetic Emissions ..............................................................................9-9

9.2.6 Thermal Requirements.....................................................................................9-9

9.3 Protection/Relay Types ....................................................................................9-9

9.3.1 Distance Protection ..........................................................................................9-9

9.3.1.1 General.............................................................................................................9-9 9.3.1.2 Supplementary 400 kV Directional Earth Fault Protection .............................9-13 9.3.1.3 Power Swing Blocking....................................................................................9-14 9.3.1.4 Fault Location Equipment...............................................................................9-15


9.3.1.5 Distance Protection Test Equipment ..............................................................9-15

9.3.2 Inverse Time Overcurrent and Earth Fault Relays .........................................9-15 9.3.3 High Set Overcurrent, Instantaneous Overcurrent and Earth Fault Protection9-16 9.3.4 Directional Relays ..........................................................................................9-16 9.3.5 Overcurrent and Earth Fault Definite Time Lag Relays..................................9-16 9.3.6 Circulating Current Protection ........................................................................9-17 9.3.7 Multi-Contact Tripping Relays ........................................................................9-17

9.4 Protection Functions.......................................................................................9-18

9.4.1 400 kV Primary Line Protection Systems .......................................................9-18 9.4.2 400 kV Main Line Protection - Group A..........................................................9-18 9.4.3 400 kV Main Line Protection Group B ............................................................9-19 9.4.4 400 kV Line Protection Signalling Equipment.................................................9-19 9.4.5 Allocation of 400 kV Line Protection Signalling Channels ..............................9-20 9.4.6 400 kV Line Reactor Protection......................................................................9-20 9.4.7 400 kV Tripping & Auto Reclose Logic ...........................................................9-20 9.4.8 400 kV Substation and Back Up Protection....................................................9-23

9.4.8.1 400 kV Overcurrent Back-up Protection .........................................................9-23 9.4.8.2 400 kV Circuit Breaker Fail and Malfunction Protection .................................9-23 9.4.8.3 400 kV Busbar Protection...............................................................................9-24

9.4.9 400/132 kV Auto Transformer & Associated Equipment Protection ...............9-26

9.4.9.1 400 kV Transformer Main Windings ...............................................................9-26

9.4.10 132 kV Transformer Protection.......................................................................9-27

9.4.10.1 11 kV Tertiary Winding ...................................................................................9-27 9.4.10.2 Tertiary Compensation Plant ..........................................................................9-28

9.4.11 132 kV Line Protection ...................................................................................9-28

9.4.11.1 132 kV Overhead Line Feeders .....................................................................9-28 9.4.11.2 132 kV Cable Feeders....................................................................................9-29 9.4.11.3 132 kV Transformer Feeders .........................................................................9-29 9.4.11.4 132 kV Backup Protection ..............................................................................9-29 9.4.11.5 132 kV Auto Reclose......................................................................................9-29

9.4.12 132 kV Busbars ..............................................................................................9-30

9.4.12.1 132 kV Busbar Protection...............................................................................9-30

9.4.13 132 kV Bus Section and Bus Couplers ..........................................................9-32

9.5 General Protection Requirements ..................................................................9-32

9.5.1 Protection Relay Power Supplies ...................................................................9-32 9.5.2 General Protection Testing & Maintenance Facilities.....................................9-32 9.5.3 Fault Recording and Data Logging.................................................................9-33 9.5.4 400 kV Fault Location.....................................................................................9-34


9.6 Relay Panel Arrangement ..............................................................................9-34 9.7 Direct Transfer Tripping and Teleprotection Signals ......................................9-34

10. COMMUNICATION EQUIPMENT..................................................................10-1

10.1 Extent of Supply .............................................................................................10-1 10.2 Power Line Carrier .........................................................................................10-1

10.2.1 400 kV Line Traps ..........................................................................................10-1 10.2.2 132 kV Line Traps ..........................................................................................10-2 10.2.3 400 kV and 132 kV Line Coupling Capacitors ................................................10-3

10.3 Power Line Carrier Terminal Equipment, Line Matching Units and Co-axial Cable ..............................................................................................................10-5 10.4 Protection Signalling Equipment ....................................................................10-5 10.5 Microwave Radio Link Equipment ..................................................................10-5 10.6 Telephone Equipment (PABX) .......................................................................10-6 10.7 Optical Fibre Based PDH/SDH Equipment.....................................................10-6

11. ELECTRICAL STATION SERVICES..............................................................11-1

11.1 Extent of Supply .............................................................................................11-1 11.2 Main 110 Volt Station Batteries & Equipment.................................................11-1 11.3 Communication 48 V Batteries and Equipment..............................................11-4 11.4 LVAC Distribution Switchgear Panels, Cabling and Socket Outlets...............11-7 11.5 Diesel Generator ............................................................................................11-9

12. CABLES .........................................................................................................12-1

12.1 General...........................................................................................................12-1 12.2 Power Cables .................................................................................................12-2 12.3 Multicore Cables.............................................................................................12-5 12.4 Cable Terminations ........................................................................................12-5 12.5 Identification of Auxiliary Cables.....................................................................12-6 12.6 Terminal Colouring and Labelling...................................................................12-6 12.7 Termination of Auxiliary Cables......................................................................12-6 12.8 Laying and Installation of Cables ...................................................................12-6 12.9 Control Cables................................................................................................12-6 12.10 Metering Cables .............................................................................................12-7 12.11 Protection Cables ...........................................................................................12-7 12.12 Earthing ..........................................................................................................12-7 12.13 Communication Cables ..................................................................................12-7 12.14 SCS Cabling...................................................................................................12-8 12.15 Cable Functions .............................................................................................12-8

13. SUBSTATION EARTHING SYSTEMS...........................................................13-1

13.1 Earthing System Design.................................................................................13-1 13.2 Step and Touch Voltage.................................................................................13-3 13.3 Equipment Earthing........................................................................................13-3 13.4 Fence and Perimeter Earthing .......................................................................13-4 13.5 GIS Substation Earthing Systems ..................................................................13-4 13.6 Earthing of Neutrals........................................................................................13-5 13.7 Surge (Lightning) Arrestors ............................................................................13-5


14. LIGHTNING PROTECTION ...........................................................................14-1

14.1 Extent of Supply .............................................................................................14-1 14.2 General...........................................................................................................14-1 14.3 General Design Data of Lightning Shielding System......................................14-1 14.4 Method of Design of Lightning Shielding System For AIS Equipment............14-2

15. INSPECTION AND TESTING ........................................................................15-1

15.1 General...........................................................................................................15-1 15.2 Inspection .......................................................................................................15-1 15.3 Testing............................................................................................................15-1

15.3.1 Approach to Testing .......................................................................................15-1 15.3.2 Responsibilities ..............................................................................................15-2 15.3.3 Test Equipment and Facilities ........................................................................15-3 15.3.4 Conduct of the Tests ......................................................................................15-3 15.3.5 Failures...........................................................................................................15-3

15.4 Tests During Commercial Operation ..............................................................15-4 15.5 Documentation ...............................................................................................15-4 15.6 Tests at Manufacturer’s Works.......................................................................15-4 15.7 Specific Equipment Tests...............................................................................15-5

15.7.1 Transformers ..................................................................................................15-5

15.7.1.1 Tests in the Manufacturer's Works .................................................................15-5 15.7.1.2 Routine tests ..................................................................................................15-5 15.7.1.3 Type Tests......................................................................................................15-6 15.7.1.4 Transformer Site Tests...................................................................................15-6

15.7.2 Reactors .........................................................................................................15-8

15.7.2.1 Routine Tests .................................................................................................15-8 15.7.2.2 Type Test .......................................................................................................15-8

15.7.3 Reactor Site Tests (Minimum) ........................................................................15-9 15.7.4 Transformer & Reactor Related Equipment ...................................................15-9

15.7.4.1 Voltage Control Equipment ............................................................................15-9 15.7.4.2 Cable Boxes and Disconnecting Chambers ...................................................15-9 15.7.4.3 Bushings.......................................................................................................15-10 15.7.4.4 Tanks and ONAN Coolers............................................................................15-10 15.7.4.5 Cooling Plant with Forced Oil Circulation .....................................................15-11 15.7.4.6 Pressure relief device...................................................................................15-11 15.7.4.7 Fans, Pumps, Motors, Pipework, Oil Sampling Devices and Valves............15-11 15.7.4.8 Oil .................................................................................................................15-12 15.7.4.9 Gas and Oil Actuated Relays .......................................................................15-12 15.7.4.10 Secondary Wiring .........................................................................................15-13 15.7.4.11 Galvanizing...................................................................................................15-14 15.7.4.12 Oil Filtering Equipment .................................................................................15-14 15.7.4.13 Minimum Acceptable Transformer Site Tests...............................................15-14

15.7.5 GIS Switchgear ............................................................................................15-15


15.7.5.1 Circuit Breaker Inspection & Testing ............................................................15-15 15.7.5.2 Circuit Breaker Type Tests...........................................................................15-15 15.7.5.3 Circuit Breaker Capacitive Current Switching Tests.....................................15-16 15.7.5.4 Circuit Breaker Low Inductive Current Switching Tests................................15-16 15.7.5.5 Circuit Breaker Internal Arcing Tests............................................................15-16 15.7.5.6 Circuit Breaker Routine Tests.......................................................................15-16 15.7.5.7 Circuit Breaker Site Tests.............................................................................15-17

15.7.6 Disconnectors and Earthing Switches..........................................................15-17

15.7.6.1 Type Tests....................................................................................................15-17 15.7.6.2 Routine Tests ...............................................................................................15-18 15.7.6.3 Site Tests .....................................................................................................15-18

15.7.7 Current Transformers (CT’s) ........................................................................15-19

15.7.7.1 Type Tests....................................................................................................15-19 15.7.7.2 Routine Tests ...............................................................................................15-19 15.7.7.3 Special Tests................................................................................................15-20 15.7.7.4 Site Tests .....................................................................................................15-20

15.7.8 Voltage Transformers and Coupling Capacitors...........................................15-20

15.7.8.1 Type Tests....................................................................................................15-20 15.7.8.2 Routine Tests ...............................................................................................15-21 15.7.8.3 Special Tests................................................................................................15-21 15.7.8.4 Site Tests .....................................................................................................15-21

15.7.9 Insulating Oil, Sulphur Hexafluoride and Compound....................................15-22

15.7.9.1 Insulating oil .................................................................................................15-22 15.7.9.2 Sulphur Hexafluoride....................................................................................15-22 15.7.9.3 Compound....................................................................................................15-22

15.7.10 Surge Diverters ............................................................................................15-22

15.7.10.1 Tests on Surge Diverters..............................................................................15-22 15.7.10.2 Tests on surge counters...............................................................................15-22

15.7.11 Line Traps ....................................................................................................15-23 15.7.12 AIS Busbar Conductor and Connections......................................................15-23 15.7.13 Post Insulators..............................................................................................15-23

15.7.13.1 Radio Influence Voltage Type Test ..............................................................15-23

15.7.14 Insulator Strings ...........................................................................................15-23

15.7.14.1 Dielectric Tests.............................................................................................15-23 15.7.14.2 Radio Influence Voltage Test .......................................................................15-23

15.7.15 Tension and Suspension Clamps and Joints ...............................................15-23

15.7.15.1 Type Tests....................................................................................................15-23 15.7.15.2 Sample Tests ...............................................................................................15-25


15.7.16 Large Hollow Porcelains...............................................................................15-25

15.7.16.1 Routine Pressure Test..................................................................................15-25 15.7.16.2 Temperature Cycle Test ...............................................................................15-25 15.7.16.3 Routine Bending Test...................................................................................15-25 15.7.16.4 Sample Bending Test ...................................................................................15-25 15.7.16.5 Ultrasonic Tests............................................................................................15-25

15.7.17 Bushing Insulators........................................................................................15-25

15.7.17.1 Type Tests....................................................................................................15-26 15.7.17.2 Routine Tests ...............................................................................................15-26

15.7.18 Structures .....................................................................................................15-27 15.7.19 132, 33 and 11 kV Power Cables.................................................................15-27

15.7.19.1 Type Tests....................................................................................................15-27 15.7.19.2 Routine Tests ...............................................................................................15-27 15.7.19.3 Tests on a Dispatch Drum of Cable..............................................................15-29 15.7.19.4 Site Test Requirements................................................................................15-29 15.7.19.5 Cable Sealing Ends......................................................................................15-31

15.7.20 LV Cables.....................................................................................................15-31

15.7.20.1 Type Tests....................................................................................................15-31 15.7.20.2 Routine Tests ...............................................................................................15-31 15.7.20.3 Site Tests .....................................................................................................15-32

15.7.21 Motors and Motor Control Equipment...........................................................15-33 15.7.22 Material.........................................................................................................15-33 15.7.23 Galvanizing...................................................................................................15-33 15.7.24 Line Traps ....................................................................................................15-34


15.7.25 Control and Indicating Panels, Instruments and Secondary Wiring .............15-35


15.7.26 Protection Equipment ...................................................................................15-35

15.7.26.1 Routine Tests ...............................................................................................15-35 15.7.26.2 Type Tests....................................................................................................15-37

15.7.27 Batteries and Associated Equipment............................................................15-37

15.7.27.1 Battery Charger ............................................................................................15-37

15.7.28 Low Voltage Switchboards ...........................................................................15-39 15.7.29 Capacitor Banks ...........................................................................................15-39

15.7.29.1 General.........................................................................................................15-39


15.7.29.2 Routine tests on unit capacitors ...................................................................15-40 15.7.29.3 Sample tests on unit capacitors ...................................................................15-40 15.7.29.4 Type Tests on Unit Capacitors .....................................................................15-41 15.7.29.5 Routine Tests on Complete Capacitor Bank ................................................15-41 15.7.29.6 Mounting Insulators for Racks of Unit Capacitors ........................................15-42

15.7.30 Series reactors .............................................................................................15-42 15.7.31 11 kV Metal Clad Switchgear .......................................................................15-42 15.7.32 GIS Building Crane.......................................................................................15-45 15.7.33 Fire Protection Equipment ............................................................................15-45 15.7.34 Substation Control System...........................................................................15-45

15.7.34.1 Approach to Testing .....................................................................................15-45 15.7.34.2 Testing Stages .............................................................................................15-46 15.7.34.3 Notice & Witnessing of Tests........................................................................15-46 15.7.34.4 Test Procedures and Result Sheets.............................................................15-47 15.7.34.5 Contractor’s Prior Tests................................................................................15-47 15.7.34.6 Fault Categories ...........................................................................................15-47 15.7.34.7 Repeat Tests ................................................................................................15-47 15.7.34.8 Fault Log ......................................................................................................15-47 15.7.34.9 Hardware Failure Reports ............................................................................15-47 15.7.34.10 Software Failure Reports..............................................................................15-48

15.8 Site Testing and Commissioning..................................................................15-49

15.8.1 Extent of Supply ...........................................................................................15-49 15.8.2 General.........................................................................................................15-49 15.8.3 Objectives.....................................................................................................15-50 15.8.4 Responsibilities ............................................................................................15-50 15.8.5 Owner Participation ......................................................................................15-51 15.8.6 Commissioning Staff ....................................................................................15-51 15.8.7 Test Equipment and Power Supplies ...........................................................15-51 15.8.8 Test Jurisdiction and Safety .........................................................................15-51 15.8.9 Equipment Repair and Replacement............................................................15-52 15.8.10 Test Methods................................................................................................15-52 15.8.11 Particular Constraints & Special Tests .........................................................15-55 15.8.12 Commissioning.............................................................................................15-55 15.8.13 Test Schedule ..............................................................................................15-55 15.8.14 Records ........................................................................................................15-55


VOLUME 1

TECHNICAL SPECIFICATION 400/132 KV GIS SUBSTATION PLANT

1-1 400kV GIS SUBSTATION – VOLUME 1

1. SYSTEM PERFORMANCE

1.1 Topographical and Meteorological Site Conditions

Site Location

Altitude above sea level - maximum m 1000

Air pressure yearly average millibars 1010.8

Air Temperatures

-Maximum Peak °C (Design maximum ambient temperature)

50

-Highest maximum for 6 hours a day °C 55

- Maximum daily average °C 40

- Maximum yearly average °C 30

- Minimum °C -10

Highest one day variation °C 25

Sun temperature in direct sunlight °C 80

Maximum ground temp at depth of 100mm 35

Humidity

Maximum relative humidity at 40degrees % 92

Minimum relative humidity % 12

Yearly average % 38/44

Pollution level

HEAVY airborne contamination

Dust Storms days/annum 21.5

Isoceraunic level(All equipment) days/annum 15

Maximum wind velocity (for design purposes) m/sec 40.2

Ice loading, radial thickness mm Nil

Total rainfall Maximum mm

500

Minimum mm 50

Maximum in one day mm 72

Average per year mm 150.8

Seismic loading Uniform Building

Code Zone 3


1.2 Electrical Design Criteria

400 kV 132 kV

(in a 400 kV substation)

11 kV Tertiary

(a) Rated System Voltage ( kV) 420 145 12

(b) Nominal System Voltage ( kV) 400 132 11

(c) System Earthing Effective Effective Impedance

(d) System Frequency (Hz) 50 50 50

(e) Estimated X/R ratio 100 - -

(f) System Short Circuit Level (MVA) 28000 9200 950

(g) System Short Circuit Level (kA) 40 40 50

(h) Busbar Rated Current (A) 4000 3150 4000

(i) Sound level (NEMA TR-1) (dB) 88 88

1.3 Insulation levels for equipment at site altitude.

400 kV

132 kV (in a 400 kV substation)

11 kV Tertiary

Lightning impulse voltage withstand level, -for switchgear and transformer bushings kVp - across insulation distance kVp

1425

1425 (+240)

650 750

95 110

Lightning impulse voltage withstand level, -for transformer windings kVp -for neutral bushings kVp -for tertiary bushings kVp

1300 125

550

-

95

95

Switching impulse voltage withstand level Phase to earth kVp Phase to phase kVp Across isolation distance kVp

1050 1575

900(+345)

Power frequency withstand voltage -for GIS switchgear (common value) kVrms -for AIS switchgear (common value) kVrms -for GIS switching gear (across isolation distance) kVrms -for AIS switching gear (across isolation distance) kVrms

650 520

815

610

275 275

315

315

38 38

45

45

Power frequency withstand voltage for transformers - for bushings kVrms

- for windings kVrms

630 570

275 230

38 38


Maximum radio influence voltage level measured at 1.1 times Us/√3 at 1 MHz µV

500

Minimum creepage to earth over insulation based on maximum system voltage (to IEC 815) mm/ kV

31

31

31

Surface stress of overhead conductors at rated system voltage kV/mm

1.65

1.4 Minimum Electrical Clearances in Air

Minimum safety clearance dimensions for open terminal equipment are shown on drawing number 1 IQ 18304.

1.5 Structures

1.5.1 Factors of Safety The minimum factors of safety for outdoor structures and associated equipment shall be as given below:

(a) Busbar or other connection, based on elastic limit of 0.1 percent (0.1%) proof stress

2.5

(b) Complete insulator units based on mechanical test

2.5

(c) Max. simultaneous short circuit current with max. wind speed

2

(d) Insulator metal fittings based on elastic limit

2.5

(e) Steel structures based on elastic limit of tension members and on buckling load; of compression members

2.5

(f) Foundations for structures against over turning and uplift under maximum simultaneous loads

2.5


1.5.2 Switchgear Structure Stresses The maximum allowable stress shall be in accordance with the Outdoor Steel Structures Section of these Specifications.

1.6 Switchgear Loadings

Loading conditions for design of outdoor switchgear and associated equipment shall be as given below:

(a) Minimum temperature of busbars and connections -100C

(b) Maximum temperature of busbars and connections 1000C plus load temp rise

(c) Wind loading As specified in Outdoor Steel Structure Section

(d) Seismic loading UCB Zone 3

(e) Ice loading Nil

(f) Tower structures shall be designed to withstand the loss of all conductors on one side of the structure.

(g) Structures shall be designed to withstand maximum loading due to short circuits.

(h) Tension load on substation terminal structure from incoming lines is 1600 kg. per phase.

1.7 Electrical Station Services

System Voltages

A.C. 380V ± 10% Three phase and Neutral 50 Hz. Effectively earthed.

D.C. (Control & Protection) 110 Volt nominal

D.C. (Communication & Interposing) 48 Volt nominal Emergency diesel generator 380 Volt, Three phase and Neutral, 50 Hz.

High resistance earthed. Main station service transformers 11,000/380 Volts ± 10% Δ/Y complete with

two load break make 380 Volt isolating switches each rated for Full Load Capacity.


2. GENERAL REQUIREMENTS

2.1 Intent and Nature of Work

This Specification provides for the design, manufacture, testing in factory, supply, delivery, off-loading on site, erection, testing on site, commissioning, setting to work and the remedy of all defects during the Defect Notification Period of the equipment detailed in the Schedules.

It shall be the responsibility of the Contractor to furnish equipment, which shall meet in all respects the performance specification and will have satisfactory durability for the prevailing site conditions.

The Contractor shall furnish all material and labour not herein specifically mentioned or included, but which may be necessary to complete any part of the work or work as a whole, in compliance with the requirements of this specification.

The detail design arrangement of the equipment shall be the responsibility of the Contractor subject to the approval of the Engineer.

The main system auto-transformers, 400 kV reactors, and 11 kV reactors may be supplied and erected by others. Where this is the case then it shall be the responsibility of the Contractor to provide all foundations for these units, together with all cabling requirements to the control cubicles.

2.2 Standards and Codes

Except where modified by this Specification all equipments and materials shall be in accordance with IEC (International Electrotechnical Commission) and ISO (International Standards Organisation) standards and recommendations. If relevant IEC and ISO standards and recommendations are not available in any case or cases then relevant British Standards or National Standards shall apply if available.

When IEC, ISO, BSI or National Standards are referred to the edition used shall be that current at the Date of Tender, together with and amendments issued to that date.

Further to that above additional standard order of preference is listed below,

IEC International Electrotechnical Commission ISO International Standards Organisation BSI British Standards Institute NS National Standards (where available) ANSI American National Standards Institute IEEE Institute of Electrical and Electronic Engineers NEMA National Electrical Manufacturers Association NEC National Electrical Code of USA NESC National Electrical Safety Code of USA UL Standards of the Underwriters Laboratories of USA IPCEA Insulated Power Cable Engineers Association of USA ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials


AWS American Welding Society

Where the use of a standard other than IEC, ISO or BS is agreed then this standard shall be used, where applicable, throughout the work. Where other standards are proposed in place of IEC, ISO or BS standards, confirmation shall be provided that the provisions of the standards are equivalent to or exceed those of equivalent IEC, ISO or BS standards.

Copies of any standards proposed in substitution for IEC, ISO or BS standards must be submitted with the Tender accompanied where necessary by English translations of the appropriate sections.

Notwithstanding any descriptions, drawings or illustrations which may have been submitted with the Tender, all details other than those shown in Schedule F, ‘Deviations from the Technical Specification’ and approved by the Engineer shall be deemed to be in accordance with the Specification and the standard specifications and codes referred to therein.

No departures from the Specification except those shown in the Schedule F, ‘Deviations from the Technical Specification’ and approved by the Engineer are to be made without the written approval of the Engineer.

2.3 Abbreviations

The following abbreviations have been used in addition to those listed under Standards and Codes.

mm millimetre cm centimetre m metre km kilometre cm2 square centimetre cm3 cubic centimetre m3 cubic metre kg kilogram kfg/cm2 kilogram force per square centimetre sec second m/sec metre per second m3/sec cubic metres per second Amp ampere V volt kV kilovolt kA kiloampere kVA kilo volt-ampere MVA mega volt-ampere kW kilowatt MW megawatt kWh kilowatt hour MWh megawatt hour ºC degrees centigrade hp horsepower


rpm revolutions per minute Hz hertz (cycles per second) rms root mean square dB decibel µV micro volt

2.4 Places of Manufacture

The manufacturer and places of manufacture, testing, and inspection of the various portions of the Contract Works shall be stated in the Schedules.

2.5 Orders Issued to Subcontractors

The Contractor shall provide three copies of all sub-contracted orders and shall be submitted to the Engineer for approval at the time such order is placed. The Contractor shall ensure the sufficient information is to be given on each sub-order to identify the material or equipment to which the sub-order applies and to notify the sub-contractor that the conditions of the Specification apply. Prices are not required on the order copies. This clause shall not apply to sub-contracts given to regular suppliers of the Contractor for stock materials and minor components.

2.6 Transport

The Contractor shall inform himself fully as to all available transport facilities, road width, and axle load limitations, loading gauges and any other requirements and shall ensure that equipment as packed for transport shall conform to the relevant limitations. Any cost arising from the use of roads or tracks, including tolls, shall be borne by the Contractor.

The Contractor shall ensure by his own inquiries that the facilities available for unloading and bearing capacity of wharfs at the port of entry is adequate for his proposed plant and equipment.

The Contractor shall be responsible for obtaining from the relevant authorities all permissions necessary to use docking, off-loading, highway, and bridge facilities required for the transportation of contract materials and plant.

2.7 Safety of personnel

The Contractor and his representatives shall in all ways comply with the Ministry of Electricity’s Safety Rules regarding electrical apparatus and the safety of men working thereon.

No testing or other work on apparatus which has been delivered to Site and which is liable to be electrically charged from any source shall be permitted except under a “Permit to Work” which will be issued for the purpose by the Ministry of Electricity’s Operating Engineer.

2.8 Compliance with regulations

All apparatus and materials supplied and all work carried out shall comply in all respects with such of the requirements of the Regulations and Acts in force in Iraq as are applicable to the Contract Works and with other applicable Regulations to which the Ministry of Electricity is subject.


2.9 General particulars and guarantees

The Works shall comply with the general particulars and guarantees stated in the Schedules.

All working methods employed and all plant and apparatus supplied under this Contract shall be to approval.

The Contractor shall be responsible for any discrepancies, errors or omissions in the particulars and guarantees, whether such particulars and guarantees have been approved by the Engineer or not.

2.10 Planning and progress reports

The Contractor shall submit for review, within 4 weeks of the starting date of the Contract, an outline design, manufacture, delivery and construction and erection chart. Within a further period of 4 weeks the Contractor shall provide a detailed programme in a format to be agreed by the Engineer; this programme shall also include details of drawing submissions.

The Contractor shall submit to the Engineer at monthly intervals, not later than the seventh day of the following month, and in such formats as may be required by the Engineer, detailed progress reports of the status of design, material procurement, manufacture, works tests, delivery to Site, erection of all plant and materials included in the Contract, testing and commissioning with regard to the agreed contract programme.

Reports shall include a chart detailing plant manufacture, delivery and erection. The chart shall indicate all phases of the work with provision for modification if found necessary during execution of the Works.

The design aspect of the progress report shall include a comprehensive statement on drawings and calculations submitted for review.

The details on material procurement shall give the dates and details of orders placed, indicating delivery dates and expected inspection dates quoted by the manufacturer. If any delivery date has an adverse affect on the contract programme the Contractor shall state the remedial action taken to ensure that delays do not occur.

The section on manufacture shall indicate dates of arrival of material, the progress of manufacture and testing and shall state the date on which the material will be ready for transport. Any events which may adversely affect completion in the manufacturer’s works shall also be reported.

All works tests and the test results shall be listed and a commentary provided. Any test failures shall be explained and the Contractor shall state his proposed actions to prevent delay to the project completion.

The shipping or transport of each order shall be monitored in the progress report and shall give the date when equipment is available for transport, the expected time of delivery to site and the dates actually achieved.


The monthly report on the site works shall be subdivided into each of the activities included in the detailed construction programme and each activity shall be monitored giving work achieved, the percentage completion and estimated completion dates for each activity, in accordance with the contract programme. The number of men working on site, both labour and supervisory staff, shall be reported together with any incidents or events that may affect the progress of site works. The progress reports shall include photographs of work items of interest and any unusual form of construction or foundation work.

A site weekly programme of work shall be provided each week during the previous week.

Any delays which may affect any milestone or completion date shall be detailed by the Contractor who shall state the action taken to effect contract completion in accordance with the contract programme.

The Contractor shall forward two copies of each progress report to the Engineer. If during the execution of the Contract the Engineer considers the progress position of any section of the work to be unsatisfactory the Engineer shall be at liberty to call progress meetings at site or in his office with a responsible representative of the Contractor.

2.11 Quality assurance

To ensure that the supply and services under the Scope of this Contract, whether manufactured or performed within the Contractor’s works or at his subcontractors’ premises or at Site or at any other place of work are in accordance with the Specification, with the Regulations and with relevant authorized standards, the Contractor shall adopt suitable quality assurance programmes and procedures to ensure that all activities are being controlled as necessary.

The quality assurance arrangements shall conform to the relevant requirements of ISO 9001.

The systems and procedures which the Contractor will use to ensure that the Works comply with the Contract requirements shall be defined in the Contractor’s Quality Plan for the Works.

The Contractor shall operate systems which implement the following:

Hold point - “A stage in material procurement or workmanship process beyond which work shall not proceed without the documented agreement of designated individuals or organizations.”

The Engineer’s written agreement is required to authorize work to progress beyond the hold points indicated in reviewed quality plans.

Notification point – “A stage in material procurement or workmanship process for which advance notice of the activity is required to facilitate witness.”

If the Engineer does not attend after receiving documented notification in accordance with the agreed procedures and with the correct period of notice then work may proceed.


2.11.1 Quality assurance requirements The Contractor and subcontractors shall, for all phases of work to be performed under the Contract, establish and implement quality assurance arrangements which, as a minimum, meet the requirements of ISO 9001, “Model for quality assurance in design, development, production, installation and servicing”.

The Contractor shall ensure that all work carried out under the Contract is performed by suitably qualified and skilled personnel and that good quality materials, which meet relevant international standard specifications, where such exist, are used.

2.11.2 Quality assurance arrangements – quality plan The Contractor shall submit a comprehensive contract specific Quality Plan for review and comment, within two weeks of award of contract.

The Quality Plan shall identify as a minimum:

(a) the Contractor’s organization and responsibilities of key management including quality assurance personnel;

(b) the duties and responsibilities assigned to staff ensuring quality of work for the Contract;

(c) the prime project documents, specifications, codes of practice, standards;

(d) the correspondence and reporting interfaces, and liaison between the Engineer and the Contractor;

(e) the procedures the Contractor intends to use to manage and control the Contract, including:

(i) the duties and responsibilities assigned to staff ensuring quality of work for the Contract;

(ii) hold and notification points;

(iii) submission of engineering documents required by the Specification;

(iv) the inspection of materials and components on receipt;

(v) reference to the Contractor’s work procedures appropriate to each activity;

(vi) inspection during fabrication/construction;

(vii) final inspection and test.

It is recommended that separate Quality Plans be submitted for the design/manufacture and construction/installation phases.

The Contractor shall review, amend and re-submit quality plans as necessary during the Contract.


2.11.3 Monitoring by the Engineer During the course of the Contract the Engineer reserves the right to monitor the implementation of the Contractor’s quality assurance arrangements.

The Contractor’s compliance with equipment, documentation, drawing, delivery, construction, installation and commissioning schedules shall be monitored by the Engineer.

Monitoring may be by means of a programme of formal audits and/or surveillance of activities at the work locations. Where deficiencies requiring corrective actions are identified the Contractor shall implement an agreed corrective action programme. The Engineer shall be afforded unrestricted access at all reasonable times to review the implementation of such corrective actions.

For site work the Engineer may monitor all aspects of the Contractor’s daily work including that of subcontractors and assess the achievement of milestones as detailed by schedule deliverables.

The Engineer reserves the right to monitor the subcontractors and the Contractor shall ensure that all subcontracts include, and subcontractors are aware of, this requirement.

2.11.4 Contractor quality audits The Contractor shall carry out a formal programme of project quality audits. These shall include audits of the design, manufacture, assembly, erection, installation, test and commissioning functions of the Contractor’s organization and those of its subcontractors and suppliers. The Engineer reserves the right to accompany the Contractor on such audits.

The Contractor shall formulate a 6 month project specific audit programme, covering 6 month periods, which shall be submitted to the Engineer for review within 4 weeks of the commencement date of the Contract and thereafter every 6 months. Any revision to the audit programme shall be forwarded to the Engineer.

2.11.5 Control of subcontractors The Contractor shall be responsible for specifying the quality assurance requirements applicable to subcontractors and suppliers, for reviewing the implementation of subcontractors’ quality assurance arrangements and for ensuring compliance with the requirements.

The Contractor shall ensure that all appropriate technical information is provided to subcontractors and suppliers. The Contractor shall, for the supply of items, plant or equipment (including those subcontracted), arrange for suitable protection for the product at all stages including delivery and installation at the site.

The Contractor shall submit, for information, a detailed programme defining the basis of control to be applied to each subcontract or supply order.


2.11.6 Inspection and tests Inspection and test plans shall be prepared for all major items of equipment/plant, defining the quality control and inspection activities to be performed to ensure that the manufacture and completion of the plant complies with the specified requirements. Inspection and test plans shall be submitted for review.

The Contractor shall submit for review, within 30 days of the Contract Award, a schedule defining the plant/equipment/systems/services which are to be subcontracted, identifying all items for which inspection and test plans will be submitted.

The Contractor shall review all inspection and test plans and associated control documents, of any subcontractors and suppliers, to ensure their adequacy prior to submission.

The Contractor shall be responsible for identifying and arranging any statutory verification activities in the country of manufacture.

Inspection and test plans may be of any form to suit the Contractor’s system, but shall as a minimum:

(a) Indicate each inspection and test point and its relative location in the production cycle including incoming goods, packing and site inspections.

(b) Indicate where subcontract services will be employed (e.g. subcontractor NDT or heat treatment).

(c) Identify the characteristics to be inspected, examined, and tested at each point and specify procedures, acceptance criteria to be used and the applicable verifying document.

(d) Indicate mandatory hold points established by the Engineer, which require verification of selected characteristics of an item of process before this work can proceed.

(e) Define or refer to sampling plans if proposed and where they will be used.

(f) Where applicable, specify where lots or batches will be used.

The Contractor shall include in all orders to subcontractors, a note advising that all materials and equipment may be subject to inspection by the Engineer as determined by the inspection and test plan. Copies of such purchase orders shall be forwarded to the Engineer.

In order to verify compliance with engineering, procurement, manufacturing requirements and programmes, the Engineer shall have access, at all times, to all places where materials or equipment are being prepared or manufactured, including the works of the Contractor’s, subcontractors or supplies of raw materials.

The Contractor shall advise the Engineer of the readiness of inspection at least 3 weeks prior to a notification point or hold point. Work shall not proceed beyond a hold point without the written agreement of the Engineer or his nominated representative.


Inspection of the plant/equipment may be made by the Engineer and could include the following activities:

(i) Periodic monitoring to confirm the effectiveness of, and the Contractor’s compliance with, the established quality plan, system procedures and inspection and test plan.

(ii) Witnessing of inspections and tests and/or verification of inspection records to be carried out at the Engineer’s discretion covering:

• compliance of raw material with specified requirements

• compliance of manufactured parts, assemblies and final items with specifications, drawings, standards and good engineering practice

• witnessing of inspection and tests

• packing for shipment including check for completeness, handling requirements, and case markings and identification.

Raw materials, components, shop assemblies, and the installation thereof, shall be subject to inspection and test by the Engineer as required by the Specification and to the extent practicable at all times and places, during the period of manufacture.

The Contractor shall keep the Engineer informed in advance of the time of starting and of the progress of the work in its various stages so that arrangements can be made for inspection and for test. The Contractor shall also provide, without additional charge, all reasonable facilities and assistance for the safety and convenience of the Engineer in the performance of his duties. All of the required tests shall be made at the Contractor’s expense, including the cost of all samples used.

The Contractor shall not offer, unless otherwise agreed, any item of equipment or system for inspection to the Engineer until all planned inspections and tests to date have been completed to the satisfaction of the Contractor.

The Engineer shall endeavour to schedule the performance of inspection and tests so as to avoid undue risk of delaying the work. In the event of postponement, by the Contractor, of tests previously scheduled, or the necessity to make additional tests due to unsatisfactory results of the original tests, or other reasons attributable to the Contactor, the Contractor shall bear all costs for new tests and the costs incurred by the Engineer or his nominated representative in re-inspecting the non-conforming item or its replacement.

The inspection and tests by the Engineer of any equipment/component or lots thereof does not relieve the Contractor of any responsibility whatever regarding defects or other failures which may be found before the end of the defects liability period.


The Contractor shall provide a quality release certificate confirming compliance with the Contract requirements and a data book, comprising the inspection, test, qualification and material records required by the pertaining specifications.

No material shall be shipped to the Site or put to work until all tests, analysis and inspections have been made and certified copies of reports of test and analysis or Contractor’s certificates have been accepted and released by the Engineer or by a waiver in writing.

2.11.7 Construction/installation phase Within 30 days of mobilization of works, inspection and test plan(s), similar in form and content to that described in 2.11.6 above, shall be submitted defining relevant inspection and test points for all stages of construction/erection, installation and commissioning. The inspection and test plans shall identify activities for which method statements shall be prepared.

Method statements shall be submitted to the Engineer for review.

Programmes of site construction works shall be submitted to the Engineer, giving notification of forthcoming test/inspections on a weekly basis.

2.11.8 Non-conformances All items or services not in accordance with the Contract technical specification, or deviating from a previously reviewed document, shall be considered non-conforming.

All such items shall be clearly identified and isolated where practical, and reported to the Engineer via a non-conformance report. Information to be provided with non-conformance notifications shall include:

(a) identification of the item(s);

(b) reference to relevant specification/drawings, including applicable revisions;

(c) reference to the application inspection and test plan stage;

(d) description of the non-conformance, with sketch where appropriate;

(e) method by which the non-conformance was detected;

(f) cause;

(g) proposed corrective action, with technical justification, where necessary;

(h) for significant non-conformances, proposed action to prevent recurrence;

(j) applicable procedures.


The Engineer shall have complete authority to accept or reject any equipment or part thereof considered not to be in accordance with the specified requirements.

Approval of any concession applications is the prerogative of the Engineer, and approval of a particular case shall not set a precedent.

Any non-conformances identified by the Engineer shall be notified by issue of the Engineer’s non-conformance report to the Contractor. Notification of re-inspection shall not be made until the completed non-conformance report, together with any applicable concession applications have been accepted by the Engineer.

Acceptance or rejection of the equipment and/or components will be made as promptly as practicable following any inspection or test involvement by the Engineer. However, failure to inspect and accept or reject equipment and/or components shall neither relieve the Contractor from responsibility for such items, which may not be in accordance with the specified requirements, nor impose liability for them on the Engineer.

2.11.9 Records Records packages to be delivered shall be agreed with the Engineer prior to setting-to-work of each phase of design, manufacture, construction, installation and commissioning.

2.11.10 Method statements Prior to commencing work, the Contractor shall submit method statements setting out full details of his methods of working. This is a hold point.

2.12 Design and standardization

Corresponding parts of all material shall be made to gauge and shall be interchangeable. When required by the Engineer the Contractor shall demonstrate this quality by actually interchanging parts. As far as possible all insulators, fittings and conductor joints and clamps should be interchangeable with the equivalent items of the existing transmission system, details of which are obtainable from the Engineer.

The Works shall be designed to facilitate inspection, cleaning and repairs, and for operation where continuity of supply is the first consideration. All apparatus shall also be designed to ensure satisfactory operation under the atmospheric conditions prevailing at the Site and under such sudden variations of load and voltage as may be met with under working conditions on the system, including those due to faulty synchronizing and short circuit.

The design shall incorporate every reasonable precaution and provision for the safety of all those concerned in the operation and maintenance of the Works and of associated works supplied under other contracts.

All mechanisms shall, where necessary, be constructed of stainless steel, brass or gunmetal to prevent mal-operation due to rust or corrosion.


Means shall be provided for the easy lubrication of all bearings and where necessary, of any mechanism or moving parts that are not oil immersed. Grease lubricators shall be fitted with nipples complying with BSI 1486 - 2, and where necessary for accessibility, the nipples shall be placed at the end of suitable extension piping.

All electrical connections and contacts shall be of ample section and surface for carrying continuously the specified currents without undue heating. Fixed connections shall be secured by bolts or set screws of ample size, adequately locked. All apparatus shall be designed to operate without undue vibration and with the least amount of noise practicable.

All apparatus shall be designed so that water cannot collect at any point and if unavoidable, shall be properly drained.

All metal jointing surfaces shall be machined or ground and all moving, rubbing or wearing surfaces shall be machined or ground. Un-machined flat steel plate covers shall be used only where the corresponding joint flange is machined. The bolt spacing and packaging material employed with such covers shall be approved by the Engineer.

Any outdoor kiosks, cubicles and similar enclosed compartments containing secondary wiring forming part of the main equipment or auxiliary equipment shall be adequately ventilated to restrict condensation and provided with suitable low temperature heaters thermostatically controlled. All contactor or relay coils and other parts shall be suitably protected against corrosion. Where ventilation is provided, disposable filters shall be fitted to prevent dust infiltration. Doors and gaskets shall be weather and dustproof. Roofs shall be of double skin construction.

All apparatus shall be designed to obviate the risk of accidental short circuit due to animals, birds and vermin.

2.13 Quality of material

All material used under this Contract shall be new and of the best quality and of the class most suitable for working under the conditions specified and shall withstand the variations of temperature and atmospheric conditions arising under working conditions without distortion or deterioration or the setting up of undue stresses in any part and without affecting the strength and suitability of the various parts for the work which they have to perform. No repair of defective parts including welding, filling and plugging will be permitted without the sanction in writing of the Engineer.

2.14 Language, weights and measures

The English language shall be used in all written communications between the Engineer and the Contractor with respect to the services to be rendered and with respect to all documents and drawings procured or prepared by the Contractor pertaining to the work.

Whenever anything is required under the terms of the Contract to be marked, printed or engraved, the English language shall be used except where otherwise provided in the Specification.


The design features of all equipment, all quantities and values which are required to be stated in the Technical Schedules and all dimensions on drawings whether prepared by the Contractor or not shall be stated in the International System of Units (SI).

2.15 Erection, supervision and checking of work on site

The carrying out of all work on the Site included in this Contract shall be supervised throughout by a sufficient number of qualified representatives of the Contractor who have had thorough experience of the erection and commissioning of similar Works.

The Contractor shall ascertain from time to time what portions of the work on the Site the Engineer desires to check, but such checking shall not relieve the Contractor from the liability to complete the Works in accordance with the Contract or exonerate him from any of his guarantees.

If at any time it appears to the Engineer that the Contractor will be unable to complete any Section of the Works in the time stipulated, then the Contractor shall, if required by the Engineer, carry on such work outside normal working hours and shall not make any claims for any extra expense thereby incurred unless, in the opinion of the Engineer, the delay is due to causes for which the Contractor would be entitled to an extension of time under the Conditions of Contract.

The Contractor shall satisfy himself as to the correctness of all connections made between the apparatus supplied under the Works and apparatus supplied under any other contract before any of the former is put into operation.

If the Engineer shall certify that defects have shown themselves in the Works, the Contractor shall, for the purpose of the maintenance after the completion of the Works provided for by the Conditions of Contract, keep on Site supervisory staff of such numbers and for such periods as the Engineer may require.

The Contractor is to keep the site, on which he erects or stores plant, reasonably clean removing all waste material resulting from the Works as it accumulates and as reasonably directed. On completion of the Works the Site is to be left clean and tidy to the satisfaction of the Engineer. Any damage done to buildings, structures and plant or property belonging to the Ministry of Electricity is to be made good at the Contractor's expense.

2.16 Bolts and Nuts

Unless otherwise approved, the threads of all nuts, bolts and studs of 7mm diameter and above shall comply with the ISO Metric Coarse Thread Standards and the threads of all nuts, bolts and studs of less than 7 mm diameter shall comply with the ISO Metric Fine Thread Standards.

Terminal bolts or studs used for carrying currents of more than 100 amp shall not be less than 16 mm in diameter. Brass terminal bolts or studs of less than 6 mm size shall not be used for electrical connections. Where a lesser size is necessary, stainless steel or phosphor bronze may be used down to and including 5 mm provided the current carrying capacity is adequate.


All nuts and pins shall be adequately locked unless agreed with the Engineer. Wherever possible, bolts shall be fitted in such a manner that, in the event of failure of locking, resulting in the nuts working loose and falling off, the bolt will remain in position.

All bolts, nuts and washers, placed in outdoor positions, shall be of approved materials and treated to prevent corrosion of the threads and electrolytic action between dissimilar metals.

All exposed bolts, nuts and washers in contact with nonferrous metallic parts shall, unless otherwise approved, be of phosphor bronze.

Where bolts are used on external horizontal surfaces where water can collect, methods of preventing the ingress of moisture to the threads shall be provided.

Each bolt or stud shall project at least one thread but not more than three threads through its nut, except when otherwise approved for terminal board studs or relay stems. If bolts and nuts are placed so that they are inaccessible by means of ordinary spanners, special spanners shall be provided.

The length of the screwed portion of the bolts shall be such that no screw thread may form part of a shear plane between members.

Taper washers shall be provided where necessary.

2.17 Cleaning and Painting

Before painting, all un-galvanized ferrous parts shall be made completely clean and free from rust, scale or grease and all external rough surfaces shall be filled.

All paints shall be applied in strict accordance with the paint manufacturer's instructions.

All painting shall be carried out on dry and clean surfaces and under suitable atmospheric and other conditions in accordance with the paint manufacturer's recommendations.

2.17.1 Works Processes (a) All steelwork, plant supporting steelwork and metalwork, except galvanised surfaces or where

otherwise specified, shall be shot blasted to BS 4232 (second quality finish) or Swedish Standard Sa2½.

(b) All surfaces shall then be painted with one coat of epoxy zinc rich primer (two pack type) to a film thickness of 50 microns. This primer shall be applied preferably by airless spray and within twenty minutes but not exceeding one hour of shot blasting.

(c) All rough surfaces of coatings shall be filed with an approved two pack filler and rubbed down to a smooth surface.

(d) The interior surfaces of all steel tanks and oil filled chambers shall be shot blasted in accordance with BS 4232 (first quality finish) or SA3 and painted within a period of preferably twenty minutes but not exceeding one hour with an oil resisting coating of a type and make to the approval of the Engineer.


(e) The interior surfaces of mechanism chambers, boxes and kiosks, after preparation, cleaning and priming as required above, shall be painted with one coat zinc chromate primer, one coat phenolic based undercoating, followed by one coat phenolic based finishing paint to a light or white colour. For equipment for outdoor use this shall be followed by a final coat of anti-condensation paint of a type and make to the approval of the Engineer, to a light or white colour. A minimum overall paint film thickness of 150 microns shall be maintained throughout.

(f) All steelwork and metalwork, except where otherwise specified, after preparation and priming as required above shall be painted with one coat metallic zinc primer and two coats of micaceous iron oxide paint to an overall minimum paint film thickness of 150 microns.

(g) Galvanized surfaces shall not be painted in the works.

(h) All nuts, bolts, washers etc, which may be fitted after fabrication of the plant shall be painted as described above after fabrication.

2.17.2 Site Painting (j) After erection at site, the interior surfaces of mechanism chambers and kiosks shall be

thoroughly examined, and any deteriorated or mechanically damaged surfaces of such shall be made good to the full Specification described in paragraph e. above.

(k) All surfaces of steelwork and metalwork included in paragraph f. above shall be thoroughly washed down, any deteriorated or otherwise faulty paint-work removed down to bare metal and made good to the full Specification described in paragraph f. then painted one further coat of phenolic based undercoating and one coat phenolic based hard gloss finishing paint to provide an overall minimum paint film thickness of 200 microns.

(m) Any nuts, bolts, washers, etc, which have been removed during site erection, or which may be required to be removed for maintenance purposes shall be restored to their original condition.

(n) All paintwork shall be left clean and perfect on completion of the works.

Exposed ungalvanized nuts, bolts and washers that may have to be removed for maintenance purposes, shall have a minimum of one coat of paint after erection.

Sufficient quantity of touch-up paint shall be supplied. The touch-up work shall be done by the Contractor.

2.18 Galvanizing

All galvanizing shall be applied by the hot dip process and shall comply with BS EN ISO 1461 but shall not be less than 0.61 kg/m2.

All welds shall be descaled, all machining carried out and all parts shall be adequately cleaned prior to galvanizing. The preparation for galvanizing and the galvanizing itself shall not adversely affect the mechanical properties of the coated material. All drilling, punching, cutting and bending of parts shall be complete and all burrs shall be removed before the galvanizing process is applied.


The threads of all galvanized bolts and screwed rods shall be cleared of spelter by spinning or brushing. A die shall not be used for cleaning the threads unless specially approved by the Engineer. All nuts shall be galvanized with the exception of the threads, which shall be oiled.

Surfaces which are in contact with oil shall not be galvanized or cadmium plated.

Partial immersion of the work will not be permitted and the galvanizing tank must therefore be sufficiently large to permit galvanizing to be carried out by one immersion.

Galvanizing of wires shall be applied by the hot dip process and shall meet the requirements of BS 10244

Galvanizing of wires shall be applied by the hot dip process and shall meet the requirements of relevant ISO Standards or B.S. 10244. The zinc coating shall be smooth, clean and of uniform thickness and free fro defects. The preparation for galvanizing and the galvanizing itself shall not adversely affect the mechanical properties of the wire.

Tests shall be carried out in accordance with the requirements of B.S. EN ISO 1461 where applicable.

Alternative processes shall not be used without the approval of the Engineer.

2.19 Labels and Plates

Each main and auxiliary item of plant shall have permanently attached to it in a conspicuous position, a rating plate of indelible material upon which shall be engraved any identifying name, type or serial number, together with details of the loading conditions under which the item of plant has been designed to operate, and such diagram plates as may be required by the Engineer.

All items of plant shall be provided with a nameplate or label indicating, where necessary, its purpose and service position. The inscriptions shall be approved by the Engineer or be as detailed in the appropriate sections of this Specification. Each phase of alternating current and each pole of direct current equipment and connections shall be coloured in an approved manner to distinguish phase or polarity.

Phases of three phase alternating current systems shall be identified as follows: -

Phase Colour R Red S Yellow T Blue

Where applicable phases on outdoor equipment shall be identified by coloured discs attached to the structures at the following locations: -

(a) On tubular busbars midway between taps and at tapping points.

(b) On tensioned busbars or other tensioned connection spans, next to the anchor points at one end of every span.


(c) On line gantries, transformer gantries, next to the anchor points.

(d) On each transformer, reactor and circuit breaker.

Such nameplates or labels shall be of stainless steel or other approved incorruptible material and shall be fixed with stainless steel screws. Where the use of enamelled iron plates is approved, the whole surface, including the back and edges, shall be properly covered and resistant to corrosion. Protective washers of suitable material shall be provided front and back on the securing screws.

Where non-hygroscopic, non-transparent or translucent heat resisting material with engraved lettering of a contrasting colour or, alternatively, in the case of indoor circuit breaker, starters, etc, of transparent plastic material with suitably coloured lettering engraved on the back is proposed then this shall be first approved by the Engineer.

Size, colour and engravings shall be subject to acceptance by the Engineer.

All inscriptions shall be in English except for Danger and Warning signs, which shall be in both English and Arabic. Colour for Danger and Warning signs shall preferably in yellow on a black background and shall be approved by the Engineer.

Items of plant, such as valves, which are subject to handling, shall be provided with an engraved chromium plated brass nameplate or label not less than 3 mm thick with engraving filled with enamel.

The interior of each piece of equipment shall be clearly marked to show the phases and for this purpose either coloured plastic discs screwed to fixed components or identification by means of plastic sleeve or tape shall be used.

In addition, each item of switchgear shall have number plates bearing the switch number allocated by the Employer according to his standard operational switch numbering scheme.

2.20 Erection Marks

Before leaving the Contractor's Works all apparatus and fittings shall be painted or stamped in two places with a distinguishing number and/or letter corresponding to the distinguishing number and/or letter on an approved drawing and material list.

The erection marks on galvanized material shall be stamped before galvanizing and shall be clearly legible after galvanizing.

All markings shall be legible; weatherproofed tags, where used, shall be durable, securely attached and duplicated.

Prior to dispatch each separate box, crate or package of plant shall be clearly labelled in the English language and bear the markings shown on the appropriate tender drawing.

Marking shall be by means of block letters not less than 13 mm high, stencilled on the box, crate or package with black paint in an easily read location. When stencilling is not possible the information shall be marked on a durable metal tag that shall be securely wired to the box, crate or package.


2.21 Tropicalization

In choosing materials and their finishes, the Contractor shall be responsible for giving due regard shall be given to the humid tropical conditions under which equipment is to operate, and the recommendations of IEC 60721 should be observed unless otherwise approved by the Engineer. The Contractor shall submit details of his previous experiences, which have proven satisfactory and which he recommends for application on the parts of the works, which may be affected by the tropical conditions. The materials and finishes used shall be subject to approval by the Engineer. In particular all switchgear and control cubicles shall be vermin-proof and topical grade materials should be used wherever possible: -

(a) Metals. Iron and steel shall generally be painted or galvanised as appropriate. Indoor parts may alternatively have chromium or copper-nickel plated or other approved protective finish. Small iron and steel parts (other than rustless steel) of all instruments and electrical equipment, the cores of electromagnets and the metal parts of relays and mechanisms shall be treated in an approved manner to prevent rusting. Cores, etc., which are built up of laminations or cannot for any other reason be anti-rust treated, shall have all exposed parts thoroughly cleaned and heavily enamelled, lacquered or compounded.

When it is necessary to use dissimilar metals in contact, these should, if possible, so be selected that the potential difference between them in the electrochemical series is not greater than 0.5 volts. If this is not possible, the contact surfaces of one or both of the metals shall be electroplated or otherwise finished in such a manner that the potential difference is reduced to within the required limits, or if practicable, the two metals shall be insulated from each other by an approved insulating material or a coating of approved varnish compound.

(b) Screws, nuts, springs pivots, etc. The use of iron and steel is to be avoided in instruments and electrical relays wherever possible. Steel screws, when used, shall be zinc, cadmium or chromium plated, or when plating is not possible owing to tolerance limitations, shall be of corrosion-resisting steel.

All wood screws shall be of dull nickel plated brass or of other approved finish. Instrument screws (except those forming part of a magnetic circuit) shall be of brass or bronze. Springs shall be of non-rusting material, e.g. phosphor-bronze or nickel silver, as far as possible. Pivots and other parts for which non-ferrous material is unsuitable are to be of approved rustless steel where possible.

(c) Fabrics, cork, paper, etc. Fabrics, cork, paper and similar materials, which are not subsequently to be protected by impregnation, shall be adequately treated with an approved fungicide. Sleeving and fabrics treated with linseed oil or linseed oil varnishes shall not be used.

(d) Wood. The use of wood in equipment shall be avoided as far as possible. When used, woodwork shall be of thoroughly seasoned teak or other approved wood that is resistant to fungal decay and shall be free from shakes and warp, sap and wane, knots, faults and other blemishes. All woodwork shall be suitably treated to protect it against the ingress of moisture


and from the growth of fungus and termite attack, unless it is naturally resistant to those causes of deterioration. All joints in woodwork shall be dovetailed or tongued and pinned as far as possible. Metal fittings where used shall be of non-ferrous material.

(e) Adhesives. Adhesives shall be specially selected to ensure the use of types which are impervious to moisture, resistant to mould growth, and not subject to the ravages of insects. Synthetic resin cement only shall be used for joining wood. Casein cement shall be used.

(f) Rubber. Neoprene and similar synthetic compounds, not subject to deterioration due to the climatic conditions, shall be used for gaskets, sealing rings, diaphragms, etc., instead of the standard rubber based materials.

Unless otherwise specified, varnish shall be applied thoroughly and completely to all moisture and fungus susceptible exposed surfaces inside equipment, such as circuit elements (resistors, capacitors, coils, etc), surfaces supporting circuit elements, interconnecting wiring and connections.

The varnish shall not be applied to any surface or part where the treatment will interfere with the operation or performance of the equipment. Such surfaces or parts shall be protected against the application of varnish. The following are examples of items and materials which shall be protected:

(i) Cable, wire, braids, and jackets flexed in operation and cable with plastic insulation.

(ii) Components and materials, such as:

• Capacitors, variable (air, ceramic or mica dielectric);

• Resistors (when wattage dissipation would be undesirably affected and when varnish may become carbonised);

• Wire-wound resistors;

• Ceramic insulators, subject to over 600 volts;

• Painted, lacquered or varnished surfaces;

• Rotating parts;

• Electron tubes;

• Tube clamps;

• Miniature tube shields;

• Plug-in relays;

• Pressure contact earths;


• Coaxial test points or receptacles;

• Windows, lenses, etc.;

• Transparent plastic parts;

• Plastic materials of the following types: polyethylene, polystyrene, polyamide, acrylic, silicone, epoxy (other than printed wiring boards), melamine-fibreglass, fluoro-carbon, vinyl and alkyd.

(iii) Organic materials that have otherwise been protected.

(iv) Electrical contacts, contact portions or mating surfaces of binding post, connectors, fuses, jacks, keys, plugs, relays, sockets (including tube sockets), switches and test points.

(v) Surfaces whose operating temperatures exceed 130 ºC or whose operating temperatures will cause carbonisation or smoking.

The varnish coating shall be applied in such a manner that the dried film will present a clear, smooth finish. The finish shall be free from air bubbles, wrinkles, filaments, spray, dust or entrapment of moisture (as indicated by blushing or darkening of film, poor adherence, etc.), running, lumping, droplets and other defects that will affect life, serviceability or appearance.

2.22 Relays, Switches, Fuses and Ancillary Equipment

All relays shall be of a type approved by the Engineer, and shall conform to IEC 60255. Relays associated with the three phases shall be marked with the appropriate phase colour and the fuses and links shall be suitable labelled. The relay elements, fuses or links associated with the R, S and T phases shall be mounted on the left, middle and right respectively, when viewed from the front of the panel. Three-pole relays of the vertical type shall have the R, S and T elements at the top, middle and bottom respectively.

All relays shall have sufficient thermal capacity for continuous energisation.

Control/selector switches for use other than on the control panel shall be of rotary type, having enclosed contacts that are accessible by the removal of covers. Switch escutcheon plates positions. “Close” or “Start” actions shall be clockwise (as seen from front); opposite actions shall be counter-clockwise.

Control switches shall be of adequate rating for the voltage and current to be carried. The required number of positions, maintained and momentary contract requirements shall be determined by the Contractor.

Control switches shall have pistol grip handles. Whilst, control, instrument and circuit selector switches shall be of a different type. Both shall be to the approval of the Engineer.


Heavy-duty oil-tight push buttons may be used as an alternative to control switches, provided they meet the voltage, continuous and interrupting current requirements.

Push buttons shall be selected to match the indicating lamps with which they will be associated. Wherever this requirement does not apply, heavy-duty oil-tight pushbuttons shall be used.

Fuses shall be of the cartridge type or of other approved type.

Fuse and link carriers and bases shall be of good quality moulded insulating materials.

Links and fuses shall be supplied with covers and located on the front of the respective cubicle. Fuses and links shall be grouped and spaced according to their function, in order to facilitate identification.

The labelling of relays, switches, pushbuttons, fuses and links shall be subject to the approval of the Engineer. Approved code symbols shall be used on diagrams and on relay, switch, pushbutton, fuse and link labels.

All panels and cubicles shall have a continuous earth bus of sectional area of not less than 15 sq. mm run along the bottom of the panels, each end being connected to the main earthing system. Metal cases of instruments, metal bases of relays and starters of the panels shall be connected to this bar by conductors of a sectional area of not less than 3 sq mm.

Current transformer and voltage transformer secondary circuits shall be complete in themselves and shall be earthed at one point only through links situated in an accessible position. Each separate circuit shall be earthed through a separate link, suitably labelled. The links shall be of the bolted type having 6mm nuts and provision for attaching test leads. Where CTs are specified for protection, the earth connections will normally be made at panels in the Relay Building.

2.23 Auxiliary Wiring and Panel Boards

(a) Auxiliary Wiring

All panel and cubical wiring shall have approved 600 V stranded copper, with heat, moisture and flame resistant insulation, conforming to IEC 60227 or BSI 6004. The insulation shall have a glossy finish and shall be incapable of supporting combustion.

All wiring, other than that for light current (telephone type) apparatus, shall be of 3/1 mm or, preferably, of 7/0.75 mm tinned copper. Single strand copper wire, if proposed, shall be approved by the Engineer. Annealed copper having a circular cross-section of 2 mm minimum diameter shall be specified, if single-stranded wire is proposed.


All cubicle wiring shall conform to the following colour code:

Colour of Wire Circuit Particulars

Red Yellow Blue

Phase connection, whether earthed or unearthed, either directly connected to the primary circuit or connected to the secondary circuits of current and voltage transformers

Black AC neutral connections, whether earthed or unearthed, either directly connected to the primary circuit or connected to the secondary circuits of current and voltage transformers

Black AC connections other than those above

Green Connections to earth

Grey Connections to DC circuits

All cubicle wiring shall be neatly run and securely fixed in such a manner that, wherever practicable, wiring can be easily checked against diagrams. Wiring passing out of the cubicles shall be run in non-rustable flexible tubes or galvanized steel tubes.

Wherever practicable, wiring shall be accommodated on the sides of the cubicles and the wires for each circuit shall be separately grouped. Back-of-panel wiring shall be so arranged that access to the connecting stems of relays and other apparatus and to contacts of control and other switches is not impeded.

Where provision is made for addition of equipment not required initially, means shall be adopted for supporting and terminating wiring during the interim period.

All wiring shall be taken to terminal boards and the wires shall not be jointed or thread between terminal points. Conductors shall be terminated in terminals of design approved by the Engineer. The terminals shall clamp the wire by means of screws. Screw pressure shall be applied by a pressure plate.

Alternatively, conductors shall be terminated with crimped connections of a suitable type or with tinned claw washers, separate washers being used for each conductor. The size of washer shall be suited to the size of conductor terminated. No solder or “push-on” or “quick-fit” type connectors shall be used in connection with any wiring. Sample terminal blocks shall be submitted for approval.

Numbers ferrules shall be fitted to all wires on panels and to all multicore cable tails. Ferrules shall be of black or white insulating material with a glossy finish to prevent adhesion of dirt. They shall not be affected by moisture or oil and shall be clearly and permanently marked. Temporary marking is prohibited.

The same ferrule number shall not be used on wires forming connections not directly in series or parallel in the same panel.


All wires which, if interfered with, may cause tripping currents to flow shall be provided with red ferrules.

At those points of interconnection between wiring carried out by separate contractors, double ferrules shall be provided on each wire where a change of number cannot be avoided. The change of numbering shall be shown on the appropriate diagrams of the equipment.

Wiring diagrams for panels and cubicles shall be drawn as if viewed from the back. They shall show the terminal boards as arranged in service.

Bus wires shall be fully insulated and shall be run separately along the top or bottom of the cubicle. Fuses and links shall be provided to enable all circuits in a cubicle, except in the lighting circuit, to be isolated from the bus wires.

Wherever practicable, all power circuits shall be kept physically separated from the control wiring and low-level signal wiring. Separate raceways shall be provided for above systems. The working voltage of each circuit shall be marked on the associated terminal boards.

The DC trip and AC voltage supplies and the wiring to main protective gear shall be segregated from those for backup protection and also from protective apparatus for special purposes and also from protections of other bays. Each such group shall be fed through separate fuses either direct from the main supply fuses or the bus wires. There shall not be more than one set of supplies to the apparatus comprising each group.

Each alarm initiation point shall be connected to the SCS.

(b) Panelboards

This specification covers the construction of all control and relay panels.

The panels shall be of unit type construction forming a rigid, self-supporting, dustproof, free standing structure. The panels shall have lift-off hinged doors at the rear for internal access. The doors shall be provided with suitable locks. The panels shall be constructed of cold rolled steel 3 mm in thickness, welded and reinforced where necessary. The surface shall be flat and free from surface blemishes and suitable stiffened to prevent buckling.

All surfaces shall be thoroughly cleaned free from all rust and foreign material, painted with a rust resistant paint, primed, sealed (sealer required on exterior only) and finished with a quick drying paint. The interior shall be glossy white and the exterior shall be of approved grey colour. A suitable quantity of finish paint shall be supplied separately to “touch-up” any damage to the finish, which may occur during shipment or installation.

Panels shall be bolted together, not welded and individual panel fronts shall be removable without disturbing any adjacent panel. All panels shall be fitted with 220 Volt single-phase receptacle and an interior light controlled by a door-operated switch located inside the panel.


The panels shall be bolted to the floor.

Any cable entering to the panels shall be tight and dustproof through suitable cable glands.

2.24 Earth Connection

Each item of equipment shall be provided with all necessary terminals, of adequate size, for connection to the earthing system.

2.25 Terminal Boards

Terminal boards shall be spaced not less than 100 mm apart. They shall be mounted vertically at the sides of the cubicle and set obliquely toward the rear doors to give easy access to terminations and to enable ferrule numbers to be read without difficulty.

The bottom of terminal boards shall be spaced at least 200 mm above the cable crutch of incoming multicore cables.

Terminal boards shall have pairs of terminals for incoming and outgoing wires and not more than two wires shall be connected to any one terminal.

Insulating barriers shall be provided between adjacent pairs of terminals. The height of the barriers and the space of the terminals shall be such as to give adequate protection while still allowing easy access to terminals.

Terminal boards shall be provided for all power, controls, instruments, annunciators, meters and relays requiring external connection.

Panel wiring shall be connected to one side of the terminal board, whilst the other side shall be reserved for outgoing cable connections.

Adequate space shall be provided on both sides of the terminal blocks for connecting wires and for ferrule markers. Terminals for external connections shall be arranged for consecutive connection of conductors within one cable. One external wire will be connected to each outgoing terminal point. At least fifteen per cent (15%) spare terminals shall be provided on each terminal block.

Terminations shall be grouped according to function and labels shall be provided on the fixed portion of the terminal boards showing the function of the group.

Covers of insulating material, preferably transparent, shall be provided on terminal boards on which connections for circuits with a voltage greater than 125 Volts are terminated.

The use of terminal boards at junction points for wires, which are not required in the associated cubicle, shall be avoided wherever practicable.


2.26 Special tools

Complete sets of all special tools including jacks and slings required for the adjustment and maintenance of the equipment as recommended by the manufacturer, for each different item of equipment, shall be supplied for each sub-station. Each set shall be individually boxed and clearly marked as to the contents, and item of equipment for which they are to be used

A detailed list of tools, jacks, slings, etc. required for repairs for all the materials being supplied under this Contract shall be included in the tender for each sub-station.

The Contractor shall ensure that all items are new and are in good condition. Slings, jacks and tools used during installation and commissioning will not be accepted.

2.27 Interchangeability

Wherever possible, all similar parts shall be made interchangeable with those of other manufacturers so as to enable substitution or replacement from spare parts easily and quickly in case of seal or other failure. In particular this shall apply to apparatus bushings. The standard to which these bushing dimensions are established shall be given.

The Contractor shall co-ordinate through the Engineer his design with that of other manufacturers to ensure the required interchangeability.

2.28 Spares

The Contractor shall list details of recommended spare parts together with their individual prices. The Engineer or Employer may order all or any of the parts and those ordered within three months of placing the Contract shall be available at the time of completion of the plant.

A separate list of spares shall include consumable items sufficient for a plant operational period of three years after commissioning, as well as essential replacement parts to cover the event of a break-down which would affect the availability or safety of the plant. The Contractor shall provide five copies (5) of the recommended list of spare parts and each copy shall show quantities, unit price and other related information.

Any spare apparatus, parts and tools shall be subject to the same specification, tests and conditions as similar material supplied under the Definite Work section of the Contract. They shall be strictly interchangeable and suitable for use in place of the corresponding parts supplied with the plant and must be suitably marked and numbered for identification and prepared for storage by greasing or painting to prevent deterioration.

All spare apparatus or materials containing electrical insulation shall be packed and delivered in cases suitable for storing such parts or material over a period of years without deterioration. Such cases shall have affixed to both the underside and topside of the lid a list detailing its contents. The case will remain the property of the Employer. It is proposed that major apparatus will be stored outdoors and small items of equipment will be stored indoors.


2.29 Packing, Shipping and Storage

A comprehensive specification covering packaging, shipping, storage and marketing that shall be used by all manufacturers, suppliers and shippers shall be written and submitted to the Engineer for approval. The specification will include, but not be limited to, any methods or procedures described herein.

The Contractor shall ensure that all materials, plant and items forming part of the works, are adequately packed for transport by sea, rail and road, to provide protection against corrosion, physical damage, contamination and damage from water, dust, noxious gases, tropical and other climatic conditions or from any other source to which they may be subjected during handling, transport and storage. Approved precautions shall be taken to protect parts containing electrical insulation against the ingress of moisture. Packing cases and packing material shall remain the property of M.O.E.

All crates, boxes, bundles, etc., required for packaging shall be carefully handled at all times and shall not be tipped, dumped, thrown or pushed from, onto or in any form of transport, during storage or at any other time.

All bright parts, liable to rust, shall receive a coat of rust-resistant composition and shall be suitably protected.

The Contractor shall take special precautions to protect bearing journals where they rest on wooden or other supports likely to contain moisture. At such points, wrappings shall be used which are impregnated with rust-resistant composition and of sufficient strength to resist chafing through, when subject to the pressure and movement likely to occur in transit.

All arrangement shall be made for all forms of transport used, to ensure that all items are transported safely and on time to their destination.

Only reputable carriers, which have regular schedules to the required destination shall be used. All the facilities, reliability and record of carriers, ports and other depots shall be investigated and arrangements shall be made to supplement any deficiencies in handling equipment and other facilities. The number of carriers shall be kept to a minimum and double handling at ports and depots shall be avoided as far as possible. The contractor shall ensure that all warehouses used en route, are suitable and that all items can be stored without any deterioration or damage from water, sunlight dust or any other cause. Consignments shall be sent in complete units and sending partial consignments shall be avoided when possible.

The Contractor shall make all the necessary arrangements for customs clearance in Iraq, the country of origin, and any countries through which goods pass.

Law of Iraq No. 157 has been passed to facilitate the entry into and transit within Iraq of goods, plant, materials and equipment necessary for the construction of major projects, including this project.

The Contractor shall obtain all the necessary export and import permits and any other documents required for the transport of goods. Copies of all forms and documents relating to customs, permits, packing lists, bills of lading and insurance, etc. shall be forwarded to the Engineer.


All parts shall be clearly marked to facilitate easy sorting and erection.

All parts shall be boxed in substantial crates or containers to facilitate handling in a safe and secure manner. Drain holes shall be provided and secure manner. Drain holes shall be provided in crate bottoms where necessary. Each crate or container shall be marked clearly on the outside of the case to show where the weight is bearing and the correct position for the slings. Each crate or container shall also be marked with the contract number and port of destination. Material intended for different locations in Iraq shall be packed separately and packages shall clearly identify the destination.

It shall be ensured that all labels, markings and colour coding on crates, boxes or containers are clear, legible, waterproof, not affected by sunlight and are securely fixed or painted thereon. Standard markings, such as “Lift here”, “No hooks”, “Fragile”, etc., shall be applied as necessary. Oil, paint and other hazardous or inflammable materials shall be marked accordingly, including “flash point”, recommended storage temperatures and detailed instructions for use. Adequate storage areas in suitable locations in Iraq shall be prepared.

2.30 Integral Electric Motors

(a) Operating Conditions

Motors shall be designed for continuous service and to the requirements of IEC 60034. They shall also be adequate for withstanding long periods of inactivity, and environmental conditions existing at the site such as high humidity, storms, salt-laden air, insects, plant life, fungus and rodents.

Only a service-proved design shall be offered. When a design is offered that has not been proved in service for at least two years, the Engineer shall be advised which parts of the motor are affected and the extent of experience with these parts.

(b) Electrical Design Features - Horsepower and Voltage

Standard manufactured horsepower sizes shall be selected. If the required horsepower falls between two listed the motor having the larger rated horsepower shall be selected.

In general, motors shall be rated in accordance with the following:

HP Phases Frequency RPM Nominal System Voltage

Less than 1 HP

1 50 Hz 1500 220

1 - 500 HP 3 50 Hz 1500

380


Motors shall be squirrel cage induction type normal torque, unless otherwise required by the load, de-rated for continuous operation in a 50 ºC ambient, totally enclosed, fan-cooled guarded construction and suitable for full voltage starting. Specific approval may be obtained from the Engineer to provide open, drip proof motor construction in certain indoor clean locations.

Motors shall have non-hygroscopic insulation, at least equivalent to class B insulation system. The thermal rating of the coil connections shall be equivalent to that of the coil insulation.

Coils shall be secured tightly in the slots. The insulation system shall be impervious to all commonly encountered contaminants, and shall withstand moderately abrasive particles and conductive dust. Motors shall have a temperature rise corresponding to the next lower insulation system class. For example, class B insulation system shall have a class A insulation system temperature rise.

Motors shall be carefully selected to ensure their suitability and compatibility with the intended driven load with adequate regard given to the locked rotor pull-up and breakdown torque and inertia requirements of the load. Where high inertia long accelerating time loads or frequent starting duties are encountered, the design will have ample thermal capacity for the intended service.

Motors shall be capable or successive starts as required by the individual driven equipment and also by the overall substation operation. A schedule of all motors on the station will be supplied for approval and shall include in the data given the starting capabilities.

Motors shall be capable of a locked rotor time in the order of 20 seconds without injurious heating and the permissible accelerating time shall be in the order of at least 30 per cent greater than the permissible locked rotor type.

Motors shall operate successfully under all conditions at rated load with a variation in the voltage or the frequency up to the following:

Plus or minus 10 per cent of the rated voltage, (with the rated frequency)

Plus or minus 5 percent of the rated frequency, (with the rated voltage)

A combined variation in voltage and frequency of plus or minus 10 per cent (sum of the absolute values) of the rated values, provided the frequency variation does not exceed plus or minus 5 per cent of the rated values.

Motors shall be dynamically balanced. The use of solder or similar deposits shall not be accepted. Parent metal removed to achieve dynamic or static balance shall be drilled out in such a manner as not to affect the structural strength of the rotor; chiselling or sawing shall not be permitted.

Enclosure parts may be made of cast iron, cast steel, sheet steel, or steel plate.

Totally enclosed, non-ventilated and totally enclosed, fan-cooled, guarded motor enclosures shall completely enclose the motor. Designs in which the stator laminations form a part of the


enclosure or in which the stator laminations are otherwise exposed to external cooling air are not acceptable.

Drip proof motors when approved shall have drip proof fully guarded enclosures. Ventilation openings shall be limited in size by design or by metal screens to prevent passage of a cylindrical rod 1.5 cm in diameter. These screens shall be made of corrosion-resistant material.

All internal parts of the motor exposed to the cooling air, such as air deflectors and fans, shall be made of corrosion-resistant material or have corrosion-resistant plating or treatment.

Nameplates shall be of non-corrosive metal construction and be securely fastened to the motor frame by means of metal screws. The following data shall be supplied on nameplates: horsepower, volts, phases, full load speed, full load amperes, frequency, locked rotor amperes, temperature rise, service factor, class of insulation system, type of enclosure, serial number, frame size and year of manufacture. If the motor has a preferred direction of rotation then this shall be indicated by a metal arrow in the preferred direction, secured to the motor frame by screws.

Antifriction bearing rating life shall be 40,000 hours minimum for direct-connected motors. Bearings shall be re-greasable with suitable fittings and shall be constructed and provided with seals so that dirt, moisture, or lubricant leakage around seals will not enter the motor.

Winding temperature detectors of the following types shall be provided for motor protection on motors of 50 H.P. and over:

Thermal temperature switch, hermetically sealed, and normally open or Three thermocouples or thermostats. Leads for thermal temperature switches and thermocouples shall be provided on motors for outdoor applications. The heaters shall have steel sheath construction, surface temperature not to exceed 200 degrees C, for 220 volt single-phase operation. They shall have sufficient capacity and be located as required to prevent condensation when the motor is not in operation. Space heaters shall be completely wired, with leads brought out to a separate terminal box.

Motor terminal boxes shall be of adequate size to permit terminating motor leads and other wiring at the motor.

The method of marking of terminal leads shall be permanent - suitable for the life of the motor. Leads shall have at least one identification marking within 150 mm of the stator frame.


2.31 Padlocks

Padlocks or other approved locking devices for circuit-breakers, isolating devices, control switches, valves, marshalling kiosks, cubicles, screened enclosures and other equipment shall be supplied under this Contract.

All padlocks and other locks shall be provided with two identical keys and two engraved, durable identification labels. It shall be impossible to open any lock with the key of any other lock provided under this Contract. Locks shall be provided in suites, provided with master key facilities.

Keys and locks shall be impressed with the Manufacturer's serial number.

Wall-mounting cabinets suitable for the accommodation of padlocks and keys while not in use shall be provided and mounted in approved positions.

The boxes and positions for locks and keys within the boxes shall be provided with durable identification labels.

2.32 Fire precautions

All machinery, apparatus, connections, cabling and other works forming part of the Contract shall be so designed, arranged and be of such material as will minimise the risk of fire and any damage that might be caused in the event of fire. The Contractor shall be responsible for sealing in an approved manner all holes in floors, walls and roofs, through which the cables and pipes may pass and for protecting the cables or pipes in an approved manner against mechanical damage or damage by fire.


3. SWITCHGEAR - GENERAL

3.1 Extent of Supply

This specification consists of design manufacture, testing, supply, delivery, installation, commissioning and guarantee of the following switchgear and the associated equipment:

Gas Insulated Switchgear Air Insulated Switchgear

(a) Circuit Breakers (b) Disconnect Switches

(b) Disconnect Switches (c) Current Transformers

(c) Current Transformers (d) Voltage Transformers

(d) Voltage Transformers (e) Lightning (Surge) Arresters

(e) Lightning (Surge) Arresters

(f) Cable Terminations

(g) Bus Ducting

3.2 Substation Design

400 kV substations shall be designed and installed as a breaker and half arrangement. 132 kV substations shall be designed and installed as a double busbar arrangement unless otherwise specified in the Scope of Works. The extent of the equipment to be provided under this contract and the allowance for future extension is specified in the Scope of Works.

The 400 kV substation design shall be suitable for high-speed and delayed, single-phase and three-phase auto-reclose operations.

The substation design shall be of robust construction, designed to prevent accidental contact being made with any live part.

The substation design shall be such as to minimize the possibility of failure due to moisture and dirt being deposited on the insulation.

The Contractor shall investigate the requirement for pre-insertions resistors on the 400 kV circuit breakers to reduce over-voltages during high-speed auto-reclose. In previous installations the 400 kV circuit breakers had been provided with 600 ohm pre-insertion closing resistors.

3.3 Current Rating & Temperature Limitations

Every current-carrying part of the switchgear equipment, including circuit breakers, SF6, oil or air-insulated isolating equipment, busbars, current transformer chambers, connections and joints shall be capable of carrying its specified rated current continuously under the atmospheric conditions existing at site, and in no part shall the temperature rise exceed the values specified in IEC 62271–100.


Every part of the switchgear equipment shall also withstand without mechanical or thermal damage the instantaneous peak currents and rated short-time currents pertaining to the rated breaking capacity of the circuit breaker. The short-time current rating of the current transformers shall not differ from that of the associated circuit breakers.


4. GAS INSULATED SWITCHGEAR (GIS)

4.1 General

The complete gas insulated switchgear shall be constructed in accordance with IEC 62271 - 203, unless otherwise stated in this Specification.

It shall be fully tested in accordance with IEC 62271-100, 62271-102 and 60694. All type tests shall be either, carried out by independent testing laboratories not associated with the manufacturers, or, witnessed by independent observers.

The Contractor shall supply suitable test equipment, interface transducers and connections to fully test the equipment offered. All Capacitive Couplers for Partial Discharge monitoring and site testing of GIS installations prior to energisation, shall be left in position for later use by the Employer, to monitor periodically the levels of discharge.

Only the analyser shall be included in the list of spares.

The signature records taken by the manufacturer prior to energisation shall be made available to the Employer for future comparison purposes.

Continuous partial discharge monitoring on the installation is not required. However, an optional cost for a continuous partial discharge monitoring system should be provided.

4.2 Gas Insulated Switchgear (GIS) Enclosures

Enclosures shall be designed in accordance with the requirements of IEC 62271 - 203. The arrangement for bolting together and the method of ensuring electrical conductivity between enclosures shall be to approval of the Engineer. The live parts of the switchgear and busbars shall be supported on barriers of insulating material with proven long-term compatibility with SF6 gas and its arc degradation products. The insulating barriers shall be discharge free at all working voltages.

The design of the enclosure shall be such as to keep loss of SF6 gas to a minimum. It is expected that replenishment of gas shall not be necessary for at least 10 years. Therefore, the gas leakage rate of any gas zone must not exceed 1 per cent of its volume per year.

Gaskets and seals shall be designed for a life expectancy of at least 30 years and this shall be demonstrated by tests or otherwise.

The switchgear gas enclosures must be sectionalised into gas zones with gas tight barriers between sections or compartments. The sections shall be arranged to minimize the extent of plant rendered inoperative when gas pressure is reduced, either by excessive leakage or for maintenance purposes, and to minimize the quantity of gas that has to be evacuated and then recharged before and after maintaining any item of equipment.


In order to minimise the extent of equipment outage in the event of gas loss when gaining access inside equipment for maintenance or when an item of equipment needs to be removed, the overall equipment shall be divided into discrete gas zones isolated from each other by gas-tight bulkheads. Separate gas-zones shall be provided for busbars and isolators. The gas-tight support insulating barriers shall be capable of withstanding a pressure differential of a vacuum on one side and on the other a pressure equal to the design gas pressure or the maximum gas pressure under conditions of an internal fault if this is greater.

The design of the enclosure assemblies shall be such that in the event of a fault, the damaged items can be replaced with minimum disturbance to the adjacent compartments.

Each gas-tight zone shall be provided with a device to relieve any pressure rise developed during internal flashover.

Overpressure created by arcing within an enclosure shall preferably be relieved by means of bursting discs venting into the atmosphere. The method of pressure release shall prevent permanent distortion of adjacent enclosures. Pressure relief by collapse of internal gas barriers is not acceptable.

The arrangement of any pressure relief device shall be such that any expulsion of disc debris or gas will be directed in a manner that will not endanger any personnel and relief vents shall be provided with deflectors or vent pipes as appropriate to satisfy this requirement.

The duration of the fault arc shall be determined by the operation of the main and back up protection equipment under all fault conditions as defined and specified in IEC 62271 - 203 and verified by relay setting calculations. During this fault period burn through of the enclosure by the fault arc is not permitted.

4.3 Gas Insulated Switchgear - Busbars and Connection Chambers

To minimise the extent of dismantling necessary to remove a part of a main busbar, it is required that discrete lengths of busbar shall be able to be withdrawn without disturbing adjacent busbar lengths; this may be achieved by the use of compressible bellows or other approved means.

The equipment shall be arranged to avoid excessive dismantling in the event of a main busbar fault. Information shall be provided with the tender to indicate the facilities incorporated in the equipment to allow removal of busbars and the consequential maximum extent of dismantling that may be involved in the event of such a fault.

All busbar connections and busbar chambers (where phase segregated busbars are employed) shall be colour coded to indicate the phase colour associated with the connection as defined elsewhere in this Specification.

All gas pipe work shall be colour coded and where more than one pipe follows a common route, each pipe shall be ring coded or labelled at regular intervals to identify the gas zone with which it is associated.


4.4 Enclosure Gas Zones

The switchgear gas enclosures must be sectionalised into gas zones with gas tight barriers between sections or compartments. The sections shall be arranged to minimize the extent of plant rendered inoperative when gas pressure is reduced, either by excessive leakage or for maintenance purposes, and to minimize the quantity of gas that has to be evacuated and then recharged before and after maintaining any item of equipment.

4.5 Expansion Joints and Flexible Connections

Expansion joints or flexible connections shall be provided in the busbars and metal enclosures to absorb the thermal expansion and contraction of the SF6 equipment. This shall include the switchgear supporting structures and shall accommodate differential settlement of the foundations and floors on which the equipment is mounted.

The method of compensating for temperature variation and differential settlement as well as the number and position of the compensating devices shall be stated in the Schedules.

4.6 Future Extensions

The design of the switchgear shall be such that it is possible to extend each end of the existing busbars without having to take more than one busbar out of service. Other circuits shall remain available for continuous uninterrupted service.

Where the distance between adjacent circuits is the width of a switchgear bay or greater, a removable straight through busbar section shall be included. It shall be possible to interchange this section with a future bay, if required, without having to take more than one bar out of service and without interruption of other connected circuits.

4.7 Gas Monitoring and Handling

All gas zones shall be filled to the design pressure with pure SF6 gas (to IEC 60376/BS 5207) and shall be monitored individually by temperature compensated pressure switches and pressure gauges.

A two-stage alarm system shall be provided for each gas section, including all relays, fascias, etc, these shall be accommodated adjacent to the switchgear. Additional repeat alarms to announce remotely each alarm stage for the group alarms of each switch bay shall be provided. The local control cubicle shall be adequately labelled to allow easy identification of signals from each gas section.

The low pressure/density alarm switches shall be arranged to provide an instruction for the operation, either automatically or manually of the circuit breakers and disconnectors adjacent to a faulted gas zone and to subsequently inhibit their further operation until suitable remedial action has been taken.

In view of the dependence of system security on the reliability of the gas density relays, and in view of the large number of relays involved in any regular relay checking procedure, the gas density relays shall have a high degree of reliability. Consideration shall be given in the design of the relay to allow easy checking of its proper operation.


Provision shall be made to enable routine measurement of the gas density in each gas-zone. The location of such measuring points shall be reasonably accessible.

Each gas density device shall be connected to the gas compartment via a self-sealing valve to facilitate easy removal of the device for maintenance. The use of stop valves for this purpose is not acceptable.

Facilities shall be provided to constantly monitor the gas density. A two-stage low gas pressure alarm and lock out system with local and remote indications shall be provided on each circuit breaker.

4.8 Local Control Cubicles

Local control cubicles shall be separate, floor mounted cubicles, provided adjacent to each switchgear section which shall contain all facilities for control, indication, local/remote control selection, protection and alarms associated with that switchgear section. A mimic diagram incorporating switches, contactors and relays necessary for local electrical control of circuit breakers, disconnectors and earth switches together with position indication shall be included.

Any plug and socket cable connections between switchgear sections and their associated local control cubicles shall be provided with a secure means of locking the connection to prevent inadvertent disconnection.

4.9 Gas Insulated Bus Duct and Bushings

SF6 insulated gas bus ducts and supporting structures and foundations shall be provided between circuits as specified in the schedules/drawings. The bus ducts shall preferably be of the phase isolated/phase segregated type. However, these shall suit the arrangement of the main GIS switchgear to which the bus duct is connected.

The SF6 enclosures shall be constructed from the same materials as the bus bar enclosures provided with the main GIS switchgear. The materials used shall prevent overheating at the specified rated currents. To reduce the effect of solar gain all SF6 insulated bus duct exposed to direct sunlight shall be covered with metallic sun shielding. The bus duct shall be complete with all components, enclosures, gas seals, gas monitors, gas compartments, gas filters, gas barrier and supporting insulators as defined in previous subsections.

The bus ducts shall be terminated at one end direct on to the GIS switchgear and at the other end on to either, outdoor porcelain-clad, or approved composite-material-clad bushings for OHL feeders, or direct onto cable sealing ends in suitable GIS enclosures.

The design of the bus ducts shall make full allowance of the thermal expansion associated with the switchgear, wall mounted bushings and any other equipments between which the bus ducts are connected. The Contractor shall fully co-ordinate the requirements of the SF6 insulated bus duct connections between the GIS switchgear feeders and the overhead line landing gantries, especially with regards to the differential settlement of the concrete floors of the switchgear room and the bus duct supporting structures.


The design and installation of the bus ducts shall as such be fully co-ordinated with the manufacturers of the equipments to be connected and shall also be co-ordinated with the civil design and works in relation to the building height, wall openings, wall/roof embedment, structural, etc, apart from the foundation requirements described herein.

The bus ducts and their supports shall be designed and tested for the specified rated normal and short time currents and for the maximum system voltage and specified test voltages. The ducts and their supports shall include any non-magnetic material or insulation necessary to prevent overheating or the induction of over-voltages in the secondary circuits.

Provision shall be allowed for access and disconnection links for equipment HV testing as may be required at site.

4.10 GIS HV Circuit Breakers (72.5 kV and Above)

4.10.1 General SF6 gas insulated (GIS) circuit breakers shall be single-pressure puffer or Self-blast or Self-blast/Rotating Arc type, suitable for indoor installations.

Circuit breakers shall be designed to IEC 62271 - 203 and fully tested in accordance with IEC 62271-100, IEC 60694 and IEC 62771-110 and with the requirements of this Specification and shall be capable of carrying the specified rated current continuously under the Site conditions.

All type tests shall be either carried out by independent testing laboratories or witnessed by independent observers.

The design of the circuit breaker shall be such that inspection and replacement of contacts, nozzles and any worn or damaged component can be carried out quickly and easily. The circuit breaker shall be fitted with the open/closed position indicators easily visible from ground level.

The inherent design of the circuit breakers shall be such that one set of contacts and nozzle (or nozzles as the case may be) shall be able to successfully interrupt at least twenty 100% fault currents without excessive erosion. When switching Capacitive (capacitor banks) and Inductive (including reactors) currents (IEC 62771-110), they produce very low over-voltages. The over-voltages produced on any switching duty must be considerably less (<<) than 2.5 pu.

The sound pressure levels of the breaker during the mechanical operations shall comply with the local and national health and safety regulations.

A suitably sized molecular sieve shall be used in the circuit breaker tank to absorb any moisture and contaminants for at least ten years in service.

The circuit breakers shall be suitable for at least 10,000 satisfactory open and close mechanical operations in accordance with IEC 62271-100.


A two-stage low gas pressure alarm and lockout system with local and remote indications shall be provided on each circuit breaker. The low pressure/density alarm switches shall instantly provide an instruction to the operator and subsequently inhibit their further operation until suitable remedial action has been taken.

The circuit breaker shall be fitted with the necessary transducers to allow regular monitoring of circuit breaker travel characteristics and all routine and site test records shall be made available to the Employer for ongoing comparison purposes. The provision of suitable test equipment for measurement of the circuit breaker timing cycle in included under this contract.

4.10.2 Circuit Breaker Operating Mechanisms 4.10.2.1 General The circuit breakers shall preferably be fitted with power-spring mechanism but other types of reliable mechanisms such as leak-free Hydraulic, Spring/Hydraulic, and Spring/SF6 gas will also be considered, provided they comply with the above circuit beaker mechanical operations requirement. A positively driven open/closed, mechanical indication device to show the position of the main contacts and with local manual operated features for tripping, closing and spring charging, visible without the necessity to open the mechanism door, shall be provided. The drive for the device shall be positive in both directions. A Pneumatic mechanism is not acceptable.

The mechanism shall fully close the circuit breaker and sustain it in the closed position against the forces of the rated making current and shall fully open the circuit breaker without undue contact bounce at a speed commensurate with that shown by tests to be necessary to achieve the rated breaking capacity in accordance with IEC 62271-100. The mechanism shall be capable of being locked in the open position. When an auto-reclose facility is specified, the mechanism shall be capable of fully closing and opening again after the auto-reclose time interval specified i.e.: performing a complete O-0.3 sec-CO-3 min-CO duty.

Mechanical counters, to record the number of closing operations, shall be provided for each circuit breaker mechanism. Circuit breakers arranged for single-pole operation shall be provided with a counter for each pole.

The mechanism and the connected interrupters shall satisfy the mechanical endurance requirements of IEC 62271-100 and all additional requirements specified herein.

Means shall be provided to prevent the mechanism from responding to a close signal when the trip coil is energised or to reclosing from a sustained close signal either after opening due to a trip signal or failure to hold in the closed position. Any relays to accomplish these provisions shall be continuously rated and mounted at the circuit breaker. The mechanism shall also incorporate manual-trip facility fitted with a guard to preclude inadvertent operation.

Means shall be provided to detect phase discrepancy in the event of one or two phases failing to complete a close or trip operation and to trip all three phases after a time delay of 1 second.


Each mechanism shall be fitted with duplicate trip coils and phase discrepancy remote indication shall also be provided.

The following facilities shall be provided at each circuit breaker local control point: -

(a) LOCAL/REMOTE selector switch. The selection of `local' operation shall inhibit the operation of the breaker from any remote source with the exception of the protection scheme.

(b) OPEN/NEUTRAL/CLOSE control switch or open and close push buttons. Where push button controls are provided the selector switch shall have a neutral position.

(c) EMERGENCY TRIP DEVICE, suitable for manual operation in event of failure of electrical supplies. The device shall be accessible without opening any access doors and distinctively labelled and protected against inadvertent operation.

The selector switch shall be lockable in both positions and the control switch shall be lockable in the neutral position.

For maintenance purposes, means shall be provided for manual operation including the slow closing and opening of those circuit breakers whose moving contacts are mechanically coupled to the direct linkage mechanism. Such operation shall be possible without the necessity of gaining access to the interior of the power unit, and shall not require excessive physical effort.

4.10.2.2 Spring Mechanisms Spring operated mechanisms are the preferred type.

Provision should be made for remote indication of `Spring charged' and `Spring charge fail' conditions.

A spare normally open spring-drive limit switch shall be provided.

It shall be possible to hand charge the operating springs with the circuit breaker in either the open or closed positions. In normal operation, recharging of the operating springs shall commence immediately and automatically upon completion of the closing operation and shall be completed within 30 seconds. Closure whilst a spring charging operation is in progress shall be prevented, and release of the springs shall not be possible until they are fully charged.

The state of charge of the operating springs shall be indicated by a mechanical device which shows `SPRING CHARGED' when operation is permissible and `SPRING FREE' when operation is not possible. A local manual spring release device shall be provided and so arranged as to prevent inadvertent operations.

Means shall be provided for hand charging the operating springs.


4.10.2.3 Hydraulic and Hydraulic/Spring Mechanisms Operating pressure shall be maintained automatically, a gauge being provided to give indication of the pressure. The pressure gauge shall be suitably damped to ensure that it is not subject to transient pressure oscillations either during pumping or during operation of the circuit breaker.

A lockout device with provision for remote alarm indication shall be incorporated in each circuit breaker to prevent operation whenever the pressure of the operating medium is below that required for satisfactory subsequent operation at the specified rating. Such facilities shall be provided for the following conditions: -

(a) Trip lockout pressure.

(b) Close lockout pressure.

(c) Auto reclose lockout pressure.

Alarm contacts shall be provided to indicate conditions a, b and c. If two trip systems are specified, then trip lockout shall apply to both systems.

A sudden fall in pressure of the operating medium to a level below which a safe operation is not possible shall not result in slow opening or closing of the circuit breaker contacts. The mechanism shall be locked in position and electrical trip and close signals shall be isolated during this period.

Facilities shall be provided to enable the available operating energy stored by the mechanism to be determined prior to operating the circuit breaker, together with an alarm in the event of the potential energy falling below a minimum rated level. Facility for hand charging of hydraulic systems shall be provided.

Circuit breakers having independent operating mechanisms on each phase shall block tripping, closing, and auto-reclosing of all phases if the operating pressure is below a minimum rated level in one or more of the mechanisms.

A pump running time meter shall be fitted and an alarm shall be provided to indicate excessive running time.

4.10.2.4 Mechanism Housings Where heaters are provided, these shall be permanently connected. Where two-stage heaters are provided, one stage shall be permanently connected and the other switched.

Means for locking shall be provided for the doors of each mechanism housing.

Mechanism housings for use outdoors shall have an IP rating of 55, those for indoor shall be IP 30.


4.11 GIS Disconnect Switches

The GIS disconnect switches shall be constructed and fully tested in accordance with the requirements of IEC 62271-102, IEC60694, IEC61128, IEC62271 - 203, and IEC 60265 and this Specification. The design shall incorporate features, which shall reduce or eliminate very high frequency voltage transients during disconnect switch operation.

The disconnecting function of disconnect switches shall still be effective when adjacent equipment components are dismantled. It is preferred that disconnect switch contacts are able to be maintained and replaced with the associated earthing switch closed.

Disconnect switches shall be fitted with position indicators visible from ground level. Viewing windows for confirming the positions of disconnect switches and earth switch contacts shall be provided unless prior agreement is reached with the Engineer.

The disconnect switches shall be provided with power and manually operated mechanisms. The power operation of the disconnect switches shall be capable of being controlled from a local or remote point.

Each power-operated disconnect switch shall be complete with a lockable LOCAL/REMOTE selector switch and OPEN/NEUTRAL/CLOSE control switch or push buttons. The function of all control and selector switches shall be clearly labelled.

Power operating mechanisms shall be capable of being locked in the open or closed positions.

The power operating mechanisms shall be suitable for the operation from voltages specified in the Schedules of this Specification.

Operating motors shall be provided with thermal overload protection and in the case of 3 phase motors, phase unbalanced protection.

The disconnect switches shall be suitable for slow closing operation. Manual operation of the disconnectors for maintenance purposes shall be provided.

The number of normally open and normally closed auxiliary switches required shall be as dictated by the particular scheme of application. Where any particular scheme requires special timing of auxiliary contacts, these shall be provided.

Electrical control circuits shall be so arranged that once initiated, an operation shall be completed unless prevented by loss of supply or operation of the motor protection. On restoration of supply the operation shall be completed.

Emergency hand operation shall be provided on power-operated disconnect switches and the power drive shall be mechanically disconnected during hand operation.

It is required that the manual effort to operate the disconnectors or earth switches shall not be greater than 150 N. There shall be adequate access for the manual operation.


In the case where the operating mechanism comprises an energy storage system followed by triggering for completion of the operation, the design shall exclude any possibility of operation by accidental triggering. Switch operation shall be effective only after full charging of the operating mechanism and after deliberate operator action.

The operating handles for manual operation of power-operated mechanisms may be detachable, in which case only two handles of each type are required per substation.

4.12 Earth Switches and Maintenance Earthing Devices

4.12.1 GIS Earth Switches Earth switches shall comply with IEC 62271-102 IEC60694 and IEC 62271 - 203 and the requirements of this Specification. They shall be provided with power and manually operated mechanisms and shall be provided on one or both sides of the disconnect switches dependent upon the locations. The electrical operation shall be performed from their control cubicles. The position indicators shall be clearly visible from the permanent working platform level.

Each separate section of switchgear that can be disconnected shall have provision for earthing in accordance with the following requirements: -

(a) All incoming and outgoing supply circuits shall be earthed by a device having a making current rating and short time rating equal to that of the associated circuit breaker.

When specified, the earth switch shall be fully insulated and the connection to earth brought out through the enclosure by means of an insulating bushing in order that the earth switch may be used for various test purposes. A removable bolted link shall be provided for connecting the insulated earth switch connection to the actual earthing terminal. The earth switch and connection bushing shall be capable of withstanding an applied power frequency voltage of 10 kV.

(b) Sections that can be established as having been disconnected shall be earthed by a device having a short time rating equal to that of the circuit breaker.

The earthing switch and the test injection point arrangement shall be suitable for a test current equal to the rated normal current of the connected busbars for a duration of 5 minutes minimum.

Earth switches on line circuits shall be capable of closing onto an energised circuit and of interrupting the current induced in the line by a parallel fully loaded line. The interrupting duty required is as specified in the schedules.

The earth switch operating mechanism shall be capable of being locked in the open or closed position.


4.12.2 Portable Maintenance Earthing Devices Where portable earthing is required, provision shall be made for applying fully rated portable maintenance earthing devices to the primary conductors of the equipment.

The design of the device shall be such that the chamber in which the device is applied can be refilled with SF6 gas when the device is in the closed position.

4.13 Current Transformers

4.13.1 General The current transformers shall comply with IEC 60044-1 & 6.

The current transformers shall have the following accuracies: -

Tariff metering Class 0.2

Instruments Class 1

Overcurrent and earth fault protection

Class 5P

Instruments and Overcurrent/earth fault protection combined

Class 1/5P

High impedance circulating current Protection

Class PX

For distance measuring protection, and current differential protection schemes the Contractor must state clearly the accuracy necessary for the correct functioning of the protection system offered and show that the secondary output of the current transformer is satisfactory for this purpose.

Current Transformers shall be of the ratios specified in Schedule D. The Contractor shall be responsible for the sizing, rating and other details pertaining to the current transformers.

The primary windings shall have a continuous and short circuit rating not less than that of the associated circuit breakers. The Contractor shall submit details of the precautions taken in the design of the primary of the transformer to prevent the mechanical and thermal stresses set up on short circuits from causing a breakdown.

Transformer circuits may be subjected to overload duties in accordance with IEC 60354; current transformers in transformer circuits shall have a rated continuous thermal current equivalent to at least the transformer long-time emergency cyclic loading capability.

Current transformers shall be of low reactance type and each core shall be electrically separated from the other windings.

The secondary windings of each set of current transformers shall be earthed at one point. Secondary terminals shall be located so that they are accessible while the equipment is alive.


Where adequate earth screens are fitted between the primary and secondary windings, earthing of the secondary winding shall be via a link mounted in the related protection or instrument cubicle. Where such earth screens are not fitted a separate earth system may be necessary.

Wherever possible the connection to earth shall be on the side of the S2 terminals.

Where multi-ratio transformer windings are specified, multi-ratio primary windings will only be considered where the protection arrangement makes these suitable for all aspects of the installation.

When multi-ratio tappings are specified, a label shall be provided indicating clearly the connections required for all ratios. These connections and the ratio in use shall also be shown on all connection diagrams.

Neutral current transformers shall be of the outdoor totally enclosed porcelain bushing type complete with mounting steelwork as required and terminal box for secondary connections.

Class PX CTs shall be specified in terms of the Turns Ratio (e.g. 1/2000) and have a secondary current rating (ISN) adequate for the primary rating (IPN) of the circuit to which it is connected; e.g. with a Turns Ratio of 1/2000, a primary rating of 2600A will require a continuous secondary rating of 1.3 A. The dimensioning factor (KX) shall be selected to ensure an adequate knee point voltage (EK), taking into account the other circuit elements and the protection function.

Line protection current transformers shall correctly transform during initial faults and following high speed three phase re-close onto faults without saturation at the system source X: R ratio (L: R) appropriate to the system voltage and shall be that used for the asymmetrical rating of the associated circuit breakers.

The voltage produced at the cores by over current or during transients on the system shall be well below the saturation voltage to ensure good transient response. The Contractor should make calculations related to the C.T. burdens and transient response according to the relevant IEC standards and submit for approval.

Where current transformers are to be mounted on apparatus provided under another contract the contractor shall be responsible for making all the necessary arrangements directly with the other contractors and for keeping the Engineer informed.

Current transformers for balanced earth fault protection shall be tested to prove compliance with the requirements of IEC 60044-6.

4.13.2 GIS Current Transformers Gas insulated current transformers shall be of the bar primary type.

The pressure of the gas at normal temperature and pressure shall be such that it remains in its gaseous state when operating at the lowest temperature stated in the Schedules.

Facilities shall be provided for constant local monitoring of the current transformer gas pressure, and topping up or sampling the gas.


For safety reasons, a bursting disc shall be fitted to the current transformer housing.

4.13.3 Current Transformer Primary Injection Tests Facilities shall be provided which allow primary injection testing of the current transformers with the minimum disturbance to the switchgear.

4.14 Voltage Transformers in GIS Switchgear

4.14.1 General Voltage transformers shall comply with the requirements of IEC 60044-2 and IEC 60186.

The Contractor shall be responsible for the sizing and rating of the voltage transformers.

Contractor shall prepare calculations that include the voltage drops on the V.T. and the connections to substantiate the ratings proposed and submit for approval.

Voltage transformers shall have the following accuracies: -


Metering and instruments Class 1.0

Protection Class 3P.

Where voltage transformers are supplied which are, or may be, connected to different sections of the busbar, it shall not be possible for the voltage transformer secondary circuits to be connected in parallel, unless the respective sections for the busbars are also connected in parallel.

An auxiliary switch or relay shall be provided in each phase of the secondary circuit of the synchronising and metering voltage supply connections to break the circuits automatically as soon as the circuit breaker is opened.

The voltage transformer secondary circuits shall be complete in themselves and shall be earthed at one point only. A separate earth link shall be provided for each secondary winding and shall be situated at the transformer but earthing will be in the relay or control building. The primary winding shall be earthed at the transformer.

The secondary windings are to be kept electrically separated. For voltage transformers, consisting of single-phase units, separate earth links for secondary windings shall be provided and shall be located at the voltage transformer.

Miniature circuit breakers (MCB) shall be provided on or adjacent to each voltage transformer, located such that they are accessible while the primary winding is alive. MCBs shall be identified by labels clearly indicating their function and phase colours.

To prevent Ferroresonance, suitable damping devices shall be provided for connection to the transformer secondaries.


4.14.2 GIS Voltage Transformers The inductive voltage transformer shall be housed in a metal tank, which complies with the internal arcing requirements of IEC 62271 - 203. The tank shall have a suitable lifting facility.

The high voltage cast resin insulators (barriers) shall be suitable for withstanding the differential pressure i.e. the normal working pressure on one side and the vacuum on the other side. They shall be compatible with SF

6 gas and its degradation products.

The pressure of the gas at normal temperature and pressure shall be such that it remains in its gaseous state when operating at the lowest temperatures stated in the Schedules.

Facilities shall be provided for constant local monitoring of the SF6 gas pressure inside the tank,

topping up or sampling the gas.

Facilities shall be provided for isolating the voltage transformer during the injection testing of GIS equipment.

For safety reasons, a bursting disc shall be fitted to the transformer housing.

4.15 Surge Arresters

4.15.1 General Surge arresters shall be of the metal-oxide, gapless type.

The design of equipment shall be in accordance with the requirements of IEC60099-1, IEC: 60099-4 and any additional requirements of this Specification. Each pressure vessel shall comply with the requirements of the appropriate CENELEC document and European standard. The testing of the equipment shall be in accordance with the requirements of IEC 60060, 60270 and 60099.

The surge arresters shall be designed to incorporate a pressure relief device to prevent shattering of the blocks/or housing, following prolonged current flow or internal flashover. They shall be designed to ensure satisfactory operation under the atmospheric conditions given in the Schedules and under such sudden variation of voltage as may be met with under working conditions on the system.

Where surge arresters form part of an overall contract for the engineering of a station and the supply of equipment, the positioning of the arresters relative to other equipment shall provide protection to the other equipment according to the requirements of IEC 60099. Insulation coordination studies shall be carried out to demonstrate these requirements and issued to the Engineer for approval.

4.15.2 Surge Counters Surge counters shall be provided and shall be operated by the discharge current passed by the surge arrester. Surge counters shall be of the electro-mechanical type and designed for continuous service, they shall be provided with a facility for continuously monitoring the leakage current.


Internal parts shall be unaffected by atmospheric conditions on Site. Alternatively, a weatherproof housing to IP 55 shall be provided as part of the Contract and this shall be designed to allow the recording device to be read without exposing the internal parts to the atmosphere.

The surge counter shall be connected in the main earth lead from the diverter in such a manner that the direction of the earth lead is not changed or its surge impedance materially altered. A bolted link shall be provided so that the surge counter may be short circuited and removed without taking the arrester out of service.

4.16 Sulphur Hexafluoride Gas (SF6)

4.16.1 General The sulphur hexafluoride SF6 gas shall comply with the requirements of IEC 60376 and BS 5207. The SF6 gas shall be supplied in 45 kg cylinders. The dew point of the gas shall be lower than -45°C. Sufficient quantity shall be provided to fill all SF6 equipment supplied under this contract plus an additional 20 per cent.

The high-pressure cylinders in which the SF6 gas is transported to, and stored on site, shall comply with the requirements of local regulations and byelaws.

Under normal conditions the SF6 gas of temperature and pressure is colourless, odourless and non-toxic. It is however five-times heavier than air and the arced gas and degradation products are toxic and harmful. It is therefore important that all personnel working on GIS equipment are kept fully informed of the potential risks and appropriate health and safety regulations.

It is therefore the responsibility of the GIS equipment supplier to provide:

- Adequate safety training to the Employer's staff regarding gas detection, the disposal of arced products and storage.

- Sufficient numbers of facemasks, goggles, hand gloves and respirators, protective clothing and gloves.

- First aid equipment including an eye wash bottle filled with distilled water.

4.16.2 Gas Handling Equipment A mobile gas handling plant for filling, evacuating, and processing the SF6 gas in the switchgear equipment, is to be supplied as part of the Contract to enable any maintenance work to be carried out. The plant shall include all the necessary gas cylinders for temporarily storing the evacuated SF6 gas as well as any other gases that may be used in the maintenance process.

The capacity of the temporary storage facilities shall be at least sufficient for storing the maximum quantity of gas that could be removed when carrying out maintenance or repair work on the largest section of the switchgear and associated equipment.


The plant provided shall be suitable for evacuating and treating the SF6 gas by the use of desiccants, driers, filters etc to remove impurities and degradation products from the gas. The capacity of the plant shall be such that the largest gas zone, with the exception of the circuit breaker, can be evacuated in less than one hour.

The plant shall also be capable of reducing the gas pressure within the circuit breaker to a value, not exceeding 8 millibars, within a time not greater than two hours.

It shall be capable of operating in the temperature range -27°C to +50°C.

4.16.3 Pipes and Couplings for the Connection of SF6 Gas All the necessary pipes, couplings, flexible tubes and valves for coupling to the switchgear equipment for filling or evacuating all the gases to be used, with all necessary instructions for the storage of this equipment, shall be provided.

4.17 Overhead Travelling Crane

4.17.1 General This contract includes the supply of all materials and works for a crane with all operating machinery, structural steel, control equipment including cables and all other parts and accessories required for proper and safe operation.

The travelling crane shall be used for erection work as well as for normal maintenance, repair and overhaul purposes.

The crane shall be complete, including, crab, hoisting machinery with motor and brakes, all lubricating devices, ropes, sheaves, hooks, flood lights, control apparatus including switchgear, runway rails, push-button controls, interlocks, limit switches, governors, protecting and alarm devices and all electric connections (cables and live rails including insulators) between all parts supplied.

4.17.2 Construction Features The design of the travelling crane has to guarantee fail-safe and satisfactory operation and has to be easy to access for service, inspection and repair.

A safety factor of 1.5 times of the maximum load is to be taken into account for all stress calculations to allow shock loading.

Adequate guards shall be provided to protect personnel from accidents caused by moving mechanism, live terminals, live conductors, etc.

The guards shall be removable for inspection and maintenance without disturbing any other part of the plant.


The Contractor shall supply suitable nameplates, giving details of the lifting capacity of the travelling crane. These nameplates shall be clearly visible to anyone who may use the cranes. The nameplates shall be inscribed in English Language.

Operating machinery and other exposed parts shall be suitably housed so that the exterior of the travelling crane will consist of smooth surface and pleasing lines.

4.17.3 Structure The minimum plate thickness for the steel construction shall be 7 mm, unless otherwise demonstrated suitable by the Contractor.

4.17.4 Crane Rails Travelling crane rails shall be provided by the Contractor. Joints between rails on opposite runway girders for the cranes shall be staggered with respect to each other and to the wheelbase of the cranes. All joints of rails shall be welded. Rail joints shall not be located over the runway girder splices. Provision for rail expansion shall be made at the end stop locations only.

Guiding of rails on the girders should be carried out with rail clamps to distance adjustment. Welded clips are not allowed.

End stops shall be designed and located to limit the maximum crane travel. The end stops shall be capable of stopping the travelling crane fully loaded and travelling at the rated speed.

4.17.5 Crane Bridge The travelling crane bridge shall consist of two girders rigidly attached to the end trucks. Gusset plates shall keep the crane in alignment.

Welded joints shall be used for the main structure of the crane, bolted joints shall be avoided whenever possible.

- In load bearing members, if a bolted joint is necessary, black bolts shall not be used.

- The strength of welded joints or joints made by friction grip bolts in structural members shall not be less than the net strength of the member. Friction grip bolts shall comply with BS 3139 and shall be fitted in accordance with the recommendations of BS 3294.

- The calculated strength of other bolted joints in structural members shall be not less than the net strength of the member plus 25 per cent. The calculated stress in screws, bolts and welds shall not exceed the appropriate permissible stress given in BS 2573.


The travelling crane girders shall be welded in structural steel box sections, with wide flange beams, standard "I" beams or reinforced beams. Girders must be symmetrical and line-of-sight must be considered along with girder design, as well as suspended crane supports. Trellis girder shall be prohibited.

The girders shall be designed to withstand all vertical loads and horizontal forces that may arise under service conditions. The vertical deflection of the girders, caused by the safe working load and the weight of the crab in the central position shall not exceed 1/1000 of the span.

The larger of the following load combinations shall control the design of the girders:

- The sum of the maximum stresses due the dead load, the weight of the trolley, the rated load, and the impact allowance.

- The sum of the maximum stresses due to the dead load, the weight of the trolley, the rated load, and an allowance for the lateral load due to acceleration and deceleration of the travelling crane.

The bridge girders shall be security braced to the end carriages to prevent cross racking. It must be impossible for the travelling crane to fall from the gantry in the event of derailment. The carriages shall be of the bogie type and shall be equipped on each end with spring buffers (bumpers).

4.17.6 Electrical Parts The travelling crane and hoists shall be so designed that adequate access for maintenance of the electrical control and operating gears is provided with suitable access facilities to enable removal of parts for maintenance and repair.

The power supply shall be provided via adequately protected contact wires along the crane track and a suspended cable on the crane girders.

The supply to the contact wires shall be via a manually operated load break isolating switch mounted at a convenient height above floor level, the switch being capable at being locked in the open position. Red indicating lights shall be arranged at collector level to show when the isolator is closed.

Motors shall be provided with quick action brakes; controllers, resistors, magnetic contractors and overload protection switches. Heavy dust and splash-proof limit switches shall be provided to prevent over hoisting, over transversal and over travelling motions.

4.17.7 Motors All motors shall be totally enclosed, wound rotor type specifically designed and built for crane service.

Motors shall be equipped with sealed antifriction, grease lubricated bearings, with provision for grease renewal.

Motors shall have tapered shaft extension on the brake end for easy removal of the brake wheel.


4.17.8 Push Button Control Station The push button control station shall be suspended by means of flexible galvanised wire rope and connected to the crane control panel by means of flexible multicore cable. The arrangement shall permit movement of the control station along the entire length of the bridge at all levels of operation.

The push button control station shall have a cost aluminium housing and shall have mechanical protection class of IP 44. The Control station shall contain besides all necessary individual push buttons for controlling operation of all crane motors, an emergency push button of the lockable type. This shall function as a master switch to cut off all power supply to the crane control panel, by switching off the master magnetic contactor.

4.17.9 Overload Relays Each motor shall be protected by overload relays adjustable for values between 150 and 300 per cent of the full load motor current.

4.17.10 Switchgear The power supply from the main collectors shall be controlled by means of a 3-phase, manually operated circuit breaker, and a 3-pole master magnetic contactor provided with under-voltage and phase reversal protection.

The operating coil of the contractor shall be wired in series with the auxiliary contacts of the adjustable, instantaneous relays in the circuit of each hoist and each travel motor, and in the circuits of all limit switches.

The circuits shall be so arranged that, on the functioning of an overload relay or the tripping of the limit switch, the flow of power to the crane will be interrupted.

4.17.11 Circuit Breaker Cabinets The main circuit breaker, lighting supply circuit breaker, master contractor, relays and protective devices shall be enclosed in a suitable steel cabinet with hinged doors. The main circuit breaker shall be so arranged that it can be operated without opening the cabinet door and that it can be locked in the open position.

4.17.12 Limit Switches Limit switches shall be provided to control the upper limits of travel of all hoist motors and at each end of travel for the bridge and trolley. Switches shall be of the totally enclosed safety type operated by the hooks or hook blocks.

4.17.13 Tools One steel toolbox shall be provided, containing complete set of ordinary and special tools needed for overhauling and repair of cranes furnished. General list of such tools shall be indicated in Tenderer's offer, and shall be detailed and submitted by the Contractor to the Engineer for checking and approval.


4.18 GIS Equipment Cable Facilities

4.18.1 Method of Termination of Cables The following requirements are applicable to switchgear equipment where the HV power cables are terminated directly in the SF

6 metal clad switchgear using cable sealing ends designed for use in SF

6

gas and shall comply with IEC 62271 - 203.

The cable connection to the switchgear shall be in accordance with IEC 60859. The switchgear contractor shall be responsible for the design, testing and supply of the insulating barrier, which provides sealing between SF

6 and air and also between SF

6 and the cable insulation. The Contractor

shall ensure that there will be no leakage of SF6 gas, oil or moisture across the sealing joint from one

chamber to the other throughout the service life of the equipment. This barrier is to be designed to accept the cable sealing end provided by others. The switchgear contractor will also be responsible for providing the electrical connection between the cable sealing end and his equipment.

Suitable cover plates and seals shall be provided as part of the switchgear contract for sealing each aperture where a cable sealing end is to be fitted, to enable the switchgear to be completely filled with SF

6 gas and tested when a cable sealing end is not available or fitted.

4.18.2 Cable Test and Isolating Facilities Testing isolation facilities shall be provided as follows:

(a) High voltage, AC pressure tests. The cable circuits will be tested with a mobile AC test set at a test voltage in accordance with IEC 62067. GIS systems will be provided with access ports and an AC test bushing to permit testing of the cable system at the above voltage.

(b) Low voltage cable tests. The cable earth switches shall be fully insulated and connected to earth through a bolted link, as specified, so that the LV cable test equipment (of rated voltage less than 10 kV) may be connected to the cable without opening any of the metal clad gas enclosures.

The insulation level of all equipment from the cable sealing end up to and including the cable circuit earth switch and disconnector (open) shall be capable of withstanding without failure or reduction of general insulation levels, the HV power cable routine AC test voltage applied for 15 minutes between the conductor and earth at the minimum rated working SF

6 gas density or pressure. The AC test

voltage shall be in accordance with the recommendations of IEC 62067.

Where three phase enclosure designs are supplied, the test facilities provided shall be such that each phase can be tested individually without the need to evacuate and refill the enclosure between tests.


4.19 Interlocking Equipment

4.19.1 Extent of Supply The Contractor shall be responsible for the designing, supply and commissioning of all interlocking schemes to the satisfaction of the Engineer. Designs are to cover the 400 kV switchgear, 400/132 kV transformers, 132 kV switchgear, tertiary loads, ac station services, dc station services. Interlocking facilities are specified in the SCS section of this Specification and these shall be in addition to the facilities in this section.

4.19.2 General All disconnecting switches and earthing devices shall be provided with interlocking features of the mechanical sequential locking type or electromechanical bolt type, and the scheme of interlocking shall be subject to approval and shall include the hand operation of apparatus which is normally electrically operated.

All mechanical interlocks shall be applied at the point at which hand power is used, so that stress cannot be applied to parts remote from that point.

Where key interlocking is employed, tripping of the circuit breaker shall not occur if any attempt is made to remove the trapped key from the mechanism. Any local emergency tripping device shall be kept separate and distinct from the key interlocking.

All electrical interlocks shall so function as to interrupt the operating supply. Failure of supply or connections to any electrical interlock shall not produce or permit faulty operation.

Electromechanical bolt interlocks shall be energized only when the operating handle of the mechanism is brought into the working position. Visible indication shall be provided to show whether the mechanism is locked or free. Means shall be provided whereby the bolt can be operated in the emergency of a failure of interlock supplies.

The guarding and screen-work of all equipment, wherever provided, shall be interlocked with the associated circuit breaker and the isolating devices in such a manner that entrance to the guarded equipment cannot be obtained unless the circuit breaker and isolating devices are open and all equipment within the guarded area is de-energized and safe. It shall not be possible to make the apparatus alive while the guarding is open.

Earthing switches are to be interlocked with the appropriate disconnect switches such that the earth switch cannot be closed unless the disconnect switches are open. Conversely, the disconnect switch cannot be closed unless the earth switch is open.

When made of steel or malleable iron, operating boxes, handles, rods, tubes and other fittings for outdoor equipment shall be galvanized.


4.19.3 400 kV Area In general the following applies to line and breaker disconnect switches:

(a) Breaker disconnects can only open when the breaker is OPEN.

(b) Breaker disconnects can close only when the breaker is OPEN.

(c) With breaker disconnects switches OPEN, it must still be possible to operate the breaker by LOCAL control only.

(d) After using breaker local control a trip signal must be applies to the breaker when switching to remote control position.

(e) Line disconnect switches can only be OPENED when the associated breakers are OPEN.

(f) Line disconnect switches can only be CLOSED when the associated breakers are OPEN.

(g) Interlocks on line disconnects must permit single beaker per line operation from any associated breaker.

(h) Earth switches shall be interlocked with its associated disconnect switches.

(j) Line reactor disconnects can only be CLOSED or OPENED if the line earth switch is Closed.

4.19.4 Transformers 400/132/11 kV In general the following applies to transformers breakers and disconnect switches:

(a) Breaker disconnect switches same as- (a), (b), (c) and (d) for 400 kV Area, above.

(b) Transformer disconnect switches (400 kV side) can only OPEN when associated transformer breakers on 400 and 132 kV voltage sides are OPEN.

(c) Transformer disconnect switches (400 kV side) can only be CLOSED when the associated transformer breakers on 400 and 132 kV sides are OPEN.

(d) Interlocks on transformer disconnect switches (400 kV side) must permit single beaker operation on the 400 kV side.

(e) Transformer disconnect switches (400 kV side) can only be CLOSED if the earthing blades on 400 kV & 132 kV side of the transformer is OPEN.

(f) Transformer disconnect switch (132 kV side) same as in (c) for 400 kV side, above.


4.19.5 132 kV Area Busbar disconnects shall be so interlocked with the appropriate busbar coupling and sectioning equipment so that sections of busbar cannot be paralleled by means of the busbar disconnect switches unless a parallel circuit is already closed through the equipment.

In all other circumstances the busbar disconnecting devices of equipment, other than busbar sectioning and coupling equipment, shall be so interlocked that their respective circuit breakers can only be coupled to one set of busbars at a time. It shall not be possible to parallel section of busbars except through the circuit breakers of the busbar coupling and sectioning equipment.

4.19.6 Tertiary Loads Individual interlocks shall be provided and maintenance requirements on each item of equipment connected to the tertiary system.

4.19.7 Site Supplies In accordance with the Electrical Station Services Section, the Contractor shall provide suitable interlocks to ensure that the Site Supply Transformers are not connected in parallel during normal operation.

The Contractor shall interlock the emergency diesel generator circuit breaker at the main secondary switchgear with the station service transformer circuit breaker such that the diesel generator can only be connected on complete loss of ac supplies.

At stations where an “Offsite” supply is available, interlocks are to be provided to prevent possible parallel operation unless agreed otherwise with the Engineer.

4.19.8 DC Station Service In accordance with the 110V DC Station Battery Section, the Contractor shall provide suitable interlocks to ensure that faults on one battery system do not endanger the other system. The interlock system proposed shall at all times prevent paralleling of the battery systems, unless one charger is supplying both batteries following the failure or maintenance of the other charger.

4.19.9 Miscellaneous Interlocks The Contractor shall bring to the Engineer’s attention any other circuitry, plant or equipment that he is designing or supplying, that may endanger the operator, maintenance staff or the system itself and provide the necessary interlocks to prevent such dangers to the satisfaction of the Engineer.

4.19.10 Locking Arrangements Locking arrangements shall be provided for:

(a) Locking each circuit breaker local manual operating handle in the “neutral” position.


(b) Locking each equipment cover, door, guard or screen in the “closed” position, as specified in this specification.

(c) Locking each isolator and earthing device handle in the “open” or “closed” positions.


5. AIR INSULATED SWITCHGEAR (AIS)

5.1 Clearances

The minimum spacing in air between conductors of different phases and clearances between conductors and earth shall be as specified in Section 1.0. The clearances and positions of apparatus including the access facilities, shall permit safe maintenance of any section of the apparatus, while the remaining sections are alive and the removal or temporary covering of circuit breakers, disconnect switches and transformers without reducing the clearance specified.

Where arcing horns or rings are provided, the minimum distance between live metal and earthed metal shall always be between the arcing rings or horns.

The minimum height from earth to the base of all post-type or bushing insulators that are not mounted vertically and the minimum height from the earth to any live part of the equipment, which is not in a screened enclosure, together with other minimum clearances shall be as specified on drawing 1 IQ 18304

5.2 Method of Line Termination

Where the connection to the station is by overhead line, all conductors will be terminated at the terminal structures. The line conductors and the tension insulators to be mounted for connection to the dead-end tower will be supplied by others, together with the necessary clamps (including bimetallic clamps). The fittings needed for the connections of the line and earth conductors to the station conductors, shall be supplied by others.

Where the connection to the station is by cable, the necessary sealing ends for the cable shall be by others. The supporting structures and connections from the sealing ends to the switchgear shall be supplied by the Contractor.

5.3 Disconnect Switches

The disconnect switches shall be constructed and fully tested in accordance with the requirements of IEC 62271-102, and this Specification.

The disconnect switches shall be capable of carrying the full-load current of the circuit and shall be arranged for operation while the equipment is alive; they will not be required to break current other than the charging current of open busbars and connections or load current shared by parallel circuits.

The minimum total length of air gap between terminals of the same pole with the disconnect switch open, shall be designed to provide an impulse voltage withstand level not less than 15 percent in excess of that specified for the insulation of the substation to earth.

Disconnect switches shall be so designed that they shall not open by forces due to currents passing through it, and shall be self-locking in both the “open” and “closed” positions.


Unless otherwise specified, disconnect switches shall be provided with electrical operating mechanisms and shall be arranged for local and remote control. Electric motor operated mechanisms shall be provided with means for emergency manual operation. The mechanism shall normally open and close all three poles simultaneously.

Means shall be provided at the local control point to prevent the local and remote control apparatus from being in operation simultaneously.

The operating mechanism shall be located so that it can be maintained while the disconnect is alive.

Service conditions require that disconnect switches shall remain alive and in service without being operated and without maintenance for periods of up to 2 years. The contacts shall therefore remain capable of carrying their rated load and short-circuit currents without over heating or welding for this period under the atmospheric and climatic conditions existing at site. After such periods, the maximum torque required to open them at the manual operating handle shall be within the capabilities of one man, e.g. approximately 35 kg, m.


5.4.1 General The current transformers shall comply with IEC 60044-1 & 6.

The current transformers shall have the following accuracies: -


Instruments Class 1

Overcurrent and earth fault protection

Class 5P

Instruments and Overcurrent/earth fault protection combined

Class 1/5P

High impedance circulating current protection

Class PX

For distance measuring protection, and current differential protection schemes the Contractor must state clearly the accuracy necessary for the correct functioning of the protection system offered and show that the secondary output of the current transformer is satisfactory for this purpose.

Current Transformers shall be of the ratios specified in Schedule D. The Contractor shall be responsible for the sizing, rating and other details pertaining to the current transformers. Details will be submitted with the tender.


The primary windings shall have a continuous and short circuit rating not less than that of the associated circuit breakers. The Contractor shall submit details of the precautions taken in the design of the primary of the transformer to prevent the mechanical and thermal stresses set up on short circuits from causing a breakdown.

Transformer circuits may be subjected to overload duties in accordance with IEC 60354; current transformers in transformer circuits shall have a rated continuous thermal current equivalent to at least the transformer long-time emergency cyclic loading capability.

Current transformers shall be of low reactance type and each core shall be electrically separated from the other windings.

The secondary windings of each set of current transformers shall be earthed at one point. Secondary terminals shall be located so that they are accessible while the equipment is alive.

Where adequate earth screens are fitted between the primary and secondary windings, earthing of the secondary winding shall be via a link mounted in the related protection or instrument cubicle. Where such earth screens are not fitted a separate earth system may be necessary.

Wherever possible the connection to earth shall be on the side of the S2 terminals.

Where multi-ratio transformer windings are specified, multi-ratio primary windings will only be considered where the protection arrangement makes these suitable for all aspects of the installation.

When multi-ratio tappings are specified, a label shall be provided indicating clearly the connections required for all ratios. These connections and the ratio in use shall also be shown on all connection diagrams.

Neutral current transformers shall be of the outdoor totally enclosed porcelain bushing type complete with mounting steelwork as required and terminal box for secondary connections.

Class PX CTs shall be specified in terms of the Turns Ratio (e.g. 1/2000) and have a secondary current rating (ISN) adequate for the primary rating (IPN) of the circuit to which it is connected; e.g. with a Turns Ratio of 1/2000, a primary rating of 2600A will require a continuous secondary rating of 1.3 A. The dimensioning factor (KX) shall be selected to ensure an adequate knee point voltage (EK), taking into account the other circuit elements and the protection function.

Line protection current transformers shall correctly transform during initial faults and following high speed three phase re-close onto faults without saturation at the system source X: R ratio (L: R) appropriate to the system voltage and shall be that used for the asymmetrical rating of the association circuit breakers.

The voltage produced at the cores by over current or during transients on the system shall be well below the saturation voltage to ensure good transient response. The Contractor should make calculations related to the C.T. burdens and transient response according to the relevant IEC standards and submit for approval.


Where current transformers are to be mounted on apparatus provided under another contract the contractor shall be responsible for making all the necessary arrangements directly with the other contractors and for keeping the Engineer informed.

Current transformers for balanced earth fault protection shall be tested to prove compliance with the requirements of IEC 60044-6.

5.4.2 Air Insulated Current Transformers Each current transformer shall be filled with oil as specified by IEC 60156 and BS 148.

The current transformers shall have fittings (d), (e), (h), (i) and (j) as specified for Voltage Transformers below.

5.4.3 Current Transformer Primary Injection Tests Facilities shall be provided which allow primary injection testing of the current transformers with the minimum disturbance to the switchgear.

5.5 Voltage Transformers and Coupling Capacitors

5.5.1 General Miniature circuit breakers (MCB) shall be provided on or adjacent to each voltage transformer, located such that they are accessible while the primary winding is alive. MCBs shall be identified by labels clearly indicating their function and phase colours.

The voltage transformer secondary circuits shall be complete in themselves and shall be earthed at one point only. A separate earth link shall be provided for each secondary winding and shall be situated at the transformer but earthing will be in the relay or control building. The primary winding shall be earthed at the transformer.

The secondary windings are to be kept electrically separated. For voltage transformers, consisting of single-phase units, separate earth links for secondary windings shall be provided and shall be located at the voltage transformer.

Where voltage transformers are supplied which are, or may be, connected to different sections of the busbar, it shall not be possible for the voltage transformer secondary circuits to be connected in parallel, unless the respective sections for the busbars are also connected in parallel.

An auxiliary switch or relay shall be provided in each phase of the secondary circuit of the synchronising and metering voltage supply connections to break the circuits automatically as soon as the circuit breaker is opened.

To prevent Ferroresonance, suitable damping devices shall be provided for connection to the transformer secondaries.


Voltage transformers shall have the following accuracies: -


Metering and instruments Class 1.0

Protection Class 3P.

5.5.2 Open Terminal Voltage Transformers and Coupling Capacitors Voltage transformers may be either the capacitor type or electromagnetic wound type. Voltage transformers shall comply with the requirements of IEC 60044-2 and IEC 60186. Coupling capacitors shall comply with IEC 60358.

The creepage and flashover distances of the high voltage insulator shall be suitable for the outdoor service conditions specified in the Schedules.

5.5.2.1 Wound Type (Electromagnetic) Voltage Transformers Wound type voltage transformers may be of the single or cascade winding type, sealed via an expansion diaphragm, and they shall comply with the requirements of IEC 60044-2.

The following facilities shall be provided: -

(a) Arrangement for terminating primary and secondary connections.

(b) Earth terminal of adequate dimensions so arranged that the earth connection cannot be inadvertently removed.

(c) Conservator tank fitted with sump and drain valve and having a capacity adequate to meet operating temperature conditions in Iraq.

(d) Single-float gas-actuated relay of an approved make with connections to terminal box.

(e) Oil level indicator of prismatic or other approved type.

(f) Earthing terminal of adequate dimensions so arranged that the earth connection cannot be inadvertently removed.

(g) Two valves, one at top and one at bottom of tank.

(h) Sampling device at bottom of tank.

(j) Lifting and jacking lugs solidly connected to tank.

(k) Approved arrangement for establishing primary and secondary connections.

(m) Secondary terminal and link box with cable gland.

Electromagnetic voltage transformers shall be filled with oil, as specified by IEC 60156 and BS 148.


5.5.2.2 Capacitor Type Voltage Transformers The design of capacitor voltage transformers shall be such that the accuracy shall not be affected by the presence of pollution on the external surface of the insulation, they shall comply with the requirements of IEC 60186.

They shall be suitable for simultaneous use as coupling and voltage measuring capacitors, and should, whenever possible, be capable of supporting the associated line trap unit. Where this is not possible the line trap may be mounted on post insulators or suspension mounting can be used, when approved by the Engineer.

These voltage transformers shall be designed to operate devices with require a potential source of approximately constant voltage ratio and negligible phase shift with respect to the high-voltage circuit.

The voltage transformers shall be high-capacitance type. The accuracy and rating shall be determined by the Contractor and shall be suitable for all devices connected thereto.

Secondary fuses shall be grouped in three-phase banks, where applicable, provided on or adjacent to each voltage transformer, located so that they are accessible while the primary is alive, and shall be provided with labels indicating their function and their phase colours. A link for each three or single-phase set of windings is to be supplied. MCBs may be offered as an alternative.

Where possible 400 kV capacitive type VTs should not be used to provide coupling for PLC equipment and 400 kV coupling capacitors should be provided separately. 132 kV capacitive type VTs will in some instances provide coupling for the PLC equipment in addition to the secondary winding.

The capacitor unit should normally be hermetically sealed.

A bushing shall be provided to enable a high frequency signal to be coupled to the capacitor unit. The bushing shall be fully protected against rain and vermin when in use, so as to avoid the possibility of being shorted to earth.

The capacitor voltage transformer mounting structure shall have provision for the following, which may be provided under a separate contract: -

(a) A line-matching unit contained in a weatherproof housing.

(b) An earthing switch capable of being operated from ground level. It shall preferably include a facility to enable the capacitor coupling unit to be earthed via the drain coil whilst simultaneously isolating the carrier equipment for test purposes.

(c) A surge diverter connected between the coupling capacitor and earth to protect the matching unit, drain coil, etc.


5.5.2.3 Oil-Filled Voltage Transformers The following facilities shall be provided:

(a) Oil level indicator of prismatic or other type, or a visual means of determining the position of the diaphragm or bellows seal from the ground level

(b) Oil sampling device located at the base of the tank where applicable.

5.5.2.4 SF6 Gas-Filled Voltage Transformers The normal gas pressure shall be such that it remains in its gaseous state when operating at temperatures down to those stated in the Schedules.

Facilities shall be provided for constant local monitoring of the voltage transformer gas pressure, and topping up or sampling the gas.

For safety reasons, a bursting disc shall be fitted to the transformer housing.

High voltage insulation may be either porcelain or a fully proven composite material.

The Contractor shall be responsible for sizing, rating and details pertaining to the voltage transformer.

Contractor should calculation about the voltage drops on the V.T. and the wires and submit for approval.

5.6 Lightning (Surge) Arresters

Surge arresters shall be of the metal-oxide, gapless type.

The design of lightning (surge) arresters shall generally be in accordance with the relevant sections of IEC 60099.

Porcelains and fittings shall be designed to comply with the applicable requirements of Section 1.0 of this specification.

(a) Construction:

The arresters shall be of robust construction and shall be designed to facilitate handling, erection and cleaning and to avoid pockets in which water can collect.

The method of assembly of the arrester shall be such that adequate contact pressure is at all times maintained between the faces of the series non-linear resistance blocks. The design of the series gaps and voltage grading resistors, shall be such that the gap setting cannot be affected by vibration, mechanical shock or change in temperature.

All joints shall be made in an approved manner such that the diverter is hermetically sealed with material, which will not deteriorate under any service conditions.


The Contractor shall provide details of grading rings that are to be provided. This shall include details of all materials used and clearances required from grading rings to earth and to live parts of other equipment.

Where necessary by site specific requirements the arrester porcelain housing shall have increased creepage length to withstand local pollution conditions to the approval of the Engineer.

(b) Surge Counters

Surge counters shall be provided and shall be operated by the discharge current passes by the lightning arrester. Surge counters shall be of the electromechanical type and designed for continuous service. They shall be robust and capable of passing repeatedly, without damage the maximum discharge current of the diverter.

Internal parts shall be unaffected by atmospheric conditions on site. Alternatively a weatherproof housing shall be provided and this shall be designed to allow the recording device to be read without exposing the internal parts to the atmosphere.

The counter shall be connected in the main earth lead from the arrester in such a manner that the direction of the earth lead is not changed or its surge impedance materially altered. Bolted links shall be provided so that he surge counter may be short-circuited and removed without taking the arrester out of service.

5.7 Safety Screening of Equipment

The minimum height from the ground of any live part of the equipment, which is not in an earthed screen enclosure, shall be as specified in Section 1.0. Where the clearances are not obtainable with an approved arrangement of the equipment, earthed screen enclosures or partitions shall be provided which shall prevent approach to any live parts. The screens and partitions necessary for each item of equipment shall be provided therewith and included in the cost thereof.

The means of access to the guarded or screened area shall be provided by interlocking with equipment.

5.8 Oil-Filled Chambers

Suitable provision shall be made for the expansion of the filling medium in all oil-filled chambers, and the chambers shall be so designed as to avoid the trapping of air or gases during the filling process.

All wiring in the vicinity of oil-filled chambers shall be insulated with oil-resistant insulation of approved quality and shall be run in rust-resistant flexible tubes or galvanized steel tubes from terminal boards conveniently situated.


5.9 Joints for Oil-Filled Chambers

All joints other than those which have to be broken shall be welded and oil-tight. Defective welded joints shall not be caulked.

All joints which have to be broken shall be metal-to-metal machine faced. Packing, if employed, shall be of a suitable type and thickness.

5.10 Oil

Where applicable, sufficient oil shall be supplied to fill all the voltage and current transformer tanks and any other oil-filled portions of the switchgear. The oil shall comply with IEC 60156 and BS 148 and shall be suitable in all respects for use in the equipment when they are operated under the conditions laid down in the specification.

Facilities shall be provided on all oil filled equipment so that it shall be possible for an observer to ascertain, while the equipment is alive, that it contains the required quantity of oil. Means, other than an indication painted on the tanks, shall be provided to indicate the oil level in each item of oil filled equipment.

5.11 Auxiliary Switches & Contactors

With each disconnecting device and earthing device, all necessary auxiliary switches, contactors and mechanisms for indication, protections, control, interlocking, supervisory and other services shall be supplied as required. Not less than four spare auxiliary switches shall be provided with each circuit breaker. All auxiliary switches shall be wired to a suitable terminal board on the fixed portion of the switchgear, whether they are in use or not, in the first instance. Auxiliary switches shall be provided to interrupt the supply of current to the tripping mechanisms of the circuit breakers when the operation of the breakers has been completed. All such switches and mechanisms shall be mounted in accessible positions clear of the operating mechanisms and shall be adequately protected. The contacts of all auxiliary switches shall be heavy duty and shall have a positive wiring action when closing.

Discharge resistors shall be provided when required, to prevent undue arcing during the operation of contactors.

Each breaker, line disconnect and breaker disconnect shall be supplied with sufficient contacts for:

(a) Remote and supervisory indication of switch position.

(b) Electrical interlock circuits.

(c) Safety breaker trip circuits on breaker disconnects.

(d) Where necessary, current transformer bus protection secondary transfer circuits.


5.12 Primary Equipment and Connections

Each item of equipment shall be provided with all necessary terminals, of adequate size, for connection to the earthing system.

5.13 Earthing Switches and Devices

5.13.1 400 kV System Each line reactor circuit shall be provided with an earthing switch for connecting the busbar to earth. These switches may be independent units or integral with the disconnecting switches. Each earthing switch will be interlocked with the relevant disconnect switches.

5.13.2 Operating Mechanisms The operating mechanisms shall be arranged for manual operation from earth level.

5.13.3 Maintenance Earths The Contractor shall provide at each substation portable earth connections. Each set shall comprise three individual phase and earth connectors, rated as follows:

400 kV Equipment 132 kV Equipment

40 kA for 1 second 40 kA for 1 second

Double conductors may be provided to assist in handling operations. If deemed necessary the Contractor shall provide suitable manual handling equipment to assist in the installation of the maintenance earths.

5.14 Busbars, Insulators and Hardware

5.14.1 Extent of Supply This Section covers: -

(a) Busbars and connections.

(b) Clamps and fittings.

(c) Insulators.

(d) Junction boxes and kiosks.

The specification for the steel structures is covered in the specification for the Civil Works.

Busbar Arrangements

Busbars will be constructed from suitably sized and rated aluminium conductor. Associated structures will be kept to the lowest possible height, whilst conforming to other sections of the specification.


5.14.2 Busbars and Connections The general construction of the busbars shall be kept as short and straight as possible and their insulated supports shall be of approved construction, mechanically strong and shall withstand all the stresses which may be imposed upon them in ordinary working due to the fixing, vibration, fluctuations in temperature, short circuit or other causes.

Safety factors shall be such that no material used for busbars, connections or for supporting the connections, where insulated or otherwise, shall be stressed to more than one-fourth of its breaking load or one-third of its elastic limit, whichever is the lesser. Provision shall be made for expansion and contraction of the busbars and connections with variations of temperature. The busbars shall be so arranged that they may be extended in length without difficulty. The design of the connectors from outdoor busbars and connections to the parts of the equipment shall be such as to permit easy dismantling for maintenance purposes.

The Contractor shall provide all necessary terminals on the switchgear for the connection to other apparatus and cables. The Contractor shall specify the busbars and connections to be provided for approval by the Engineer.

The busbars and connection shall be so arranged and supported that under no circumstances, including short circuit conditions, can the clearance from earthed metalwork or from other conductors be less than distances specified in Section 1.0.

Stranded conductors having hollow cores shall be stranded around non-ferrous metal spacers of approved type. The number and diameters of the individual wires, forming the finished conductor or the thickness of tubes, shall be defined by the Supplier to the approval of the Engineer.

Overhead conductors, carried by the substation structures, shall be erected with such sags and tensions that the maximum loading of the structures is not exceeded when the conductors at 65 degrees C, are subject to the transverse wind pressure as specified.

Means for adjusting the sags and tension of overhead conductors shall be provided and shall be preferably by means of sag adjusting plates. The method adopted and range of adjustment provided shall be approved by the Engineer.

All clamps and other fittings for attaching the connections to the busbars, switchgear, transmission lines and the bare copper terminals rods on the bushing insulators shall be provided. All fittings shall be in accordance with this Specification and joints shall be of approved design. Where dissimilar metals are connected, means shall be provided to prevent electro-chemical action and corrosion. Joint surfaces of copper or copper alloy fittings shall be tinned.

Stranded copper connections shall be tinned at clamping points and if of the hollow pattern shall be supported against crushing at such points by sweating solid or by insertion of a suitable plug. Scratches, burrs and projections on welds shall not exceed 3 mm in depth or projection.


5.14.3 Insulators 5.14.3.1 General Porcelain insulators shall be to IEC 60137 where applicable.

Porcelain shall be sound, free from defects and thoroughly vitrified so that the glaze is not dependent upon for insulation. The glaze shall be smooth, hard, and shall completely cover all parts of the insulator, which are exposed to contamination.

Outdoor insulators and fittings shall be designed to withstand all atmospheric conditions due to weather, ozone, acids, alkalis, dust, sandstorms or rapid changes of temperatures, under working conditions existing at site.

5.14.3.2 Electrical Design of Insulators The electrical characteristics of insulators shall be as specified in design criteria.

Where the use of extended creepage insulation is specified, the total creepage distance over the external porcelain surface of bushings or insulators, measured in millimetres, shall not be less numerically than the working voltage between phases in kilovolts divided by a factor of 31. The protected creepage distance shall also be not less than half the minimum total creepage and shall be that portion of the external surface lying in shadow when the insulator is illuminated at 90 degrees to its axis. For post insulators comprising standard units, the above requirements shall, unless otherwise specified, be met by the additional of an approved number of additional units to the normal assembly.

5.14.3.3 Mechanical Design of Insulators The strength of the insulators, as given by the electromechanical test load, shall be such that the factor of safety when the insulators are supporting the maximum working loads shall not be less than 2.5.

The design shall be such that stresses due to expansion and contraction in any part of the insulator and fittings shall not lead to the development of defects.

Porcelain shall not connect directly with hard metal and, where necessary, yielding material shall be interposed between the porcelain and the fitting. All joint faces of porcelain shall be accurately ground and free from glaze. All fixing material used shall be of approved quality and applied in an approved manner, and shall not enter into chemical action with the metals parts or cause fracture by expansion in service. Where cement is used as a fixing medium, cement thickness shall be as small and even as possible and proper care shall be taken correctly to centre and locate the individual parts during cementing.

The design of all insulators shall be such as to permit easy cleaning.


5.14.3.4 Marking of Insulators Each insulator and bushing shall have marked upon it the manufacturer’s identification name or trademark and such other mark as may be necessary to assist in the representative selection of batches for the purposes of the type tests stated in Section 4.6. Each porcelain insulator shall, in addition, be marked to indicate the date of firing. Each tension and suspension insulator shall also be marked with the guaranteed electromechanical strength. All marks shall be visible after assembly of fittings and shall be imprinted and not impressed. For porcelain insulators the marks shall be imprinted before firing and for paper insulators before varnishing, in such a manner that the marks shall be permanent and clearly legible on the finished insulator.

When a batch of insulators, bearing a certain identification mark, has been rejected, no further insulators bearing this mark shall be submitted. The Contractor shall satisfy the Engineer that adequate steps will be taken to mark or segregate the insulators constituting the rejected batch in such a way that there shall be no possibility of the insulators subsequently being resubmitted for test or supplied for future use.

5.14.3.5 Suspension and Tension Insulators Suspension and tension insulators shall consist of porcelain units with ball and socket fittings. Insulators units and the balls and sockets of the units and of associated fittings shall be in accordance with BS EN 60137.

The individual units to both suspension and tension insulator sets shall be identical and interchangeable.

Retaining pins or locking devices for insulator units shall be of phosphor bronze or other approved material. They shall be so formed that, when set and under any conditions, nothing but extreme deformation of the retaining pin or locking device will allow separation of the insulator units or fittings or will permit accidental displacement for the retaining pins or locking devices. Their design shall be such as to allow easy removal or replacement of insulator units or fittings without removal of the insulator sets from the structures. Retaining pins or locking devices, when in position, shall be incapable of rotation.

5.14.3.6 Post-Type Insulators Post-type insulators, were required, shall be built up of strong interchangeable units and shall be designed to withstand all shocks which may be met in operation. Post-type insulators of uniform composition shall be designed so that they can be used either upright or inverted.

5.14.3.7 Bushing-Type Insulators Bushing insulators provided for connection to bare conductors shall be of an approved type and shall be provided with suitable connectors.

Bushing insulators shall be filled with oil of a suitable type. Means shall be provided to ensure maintenance of the correct oil level and level gauges shall be such as to give reliable indication to an observer at ground level with the equipment alive.

All condenser type bushings shall be provided with a tapping, brought out to a separate terminal for testing purposes on site.


5.14.4 Clamps and Fittings Conductor suspension and tension clamps shall be of suitable types and shall be as light as possible. Where applicable, clamps for steel cored aluminium conductors shall be lined with soft aluminium liners to prevent damage to the conductors. Suspension, compression fittings and tension clamps shall be designed to avoid any possibility of deforming the stranded conductor and separating the individual strands.

Clamps and fittings made of steel or malleable iron shall be galvanized in accordance with this specification. All bolts and nuts shall be as specified and shall be locked in an approved manner.

Conductor tension clamps or compression fittings shall not permit slipping of, or damage to, or failure of the complete conductor or any part thereof at a load less than 95 per cent of the ultimate strength of the conductor.

Suspension clamps shall be free to pivot in the vertical plane about a horizontal axis passing through and transverse to the centre line of the conductor. Suspension clamps shall permit the complete conductor to slip before failure to the latter occurs, but the conductor shall be clamped in an approved manner. All conductor grooves and bell-mouths shall, after galvanizing, be smooth and free from waves, ridges or other irregularities.

Bolted-type tension clamps shall be radiuses at the mouth as specified for suspension clamps and the above specified requirements for the conductor grooves shall be taken into account where applicable.

In tension clamps in which the conductor is necessarily cut, approved means shall be taken to treat the cut ends of the conductors to prevent ingress of air or moisture. The mechanical efficiency of such tension clamps shall not be affected by methods of erection involving the use of “come along” or similar erection clamps before, during or after assembly and erection of the tension clamp itself.

Tension insulator sets and clamps shall be arranged to give a minimum clearance of 150 mm between the jumper conductor and the rim of the live end of the insulator unit or string.

Except when erected with the extra insulator unit, each tension insulator set shall be provided with a link whose centre distance is equal to the centre distance of the tension insulator unit, so that the total length of the tension insulator set is equal to that of the set including the extra unit.

All split pins for securing the attachment of individual units of insulator sets shall be of phosphor bronze and those for securing fittings shall be stainless steel and shall be backed by washers of approve size and thickness.

The factor of safety of safety of the fittings, when supporting the maximum working load, shall not be less than 2 ½ based on the elastic limit of the material


5.14.5 Corona Conductors shall be designed so that the voltage stress at the conductor surface shall not exceed a value equivalent to 16.5 kV (rms)/cm at sea level.

All equipment shall be tested as specified in the Specification and shall be corona free at the specified test voltage.

5.14.6 Guard Rings or Arcing Horns Guard rings or arcing horns or rings of approved type, size and material shall be attached to bushing and post-type insulators and to the conductor clamp fittings of all suspension and tension insulator sets but not to the clamps themselves. The design of the arcing horns or rings shall be such as to reduce, as far as reasonably possible, cascading and damage to clamps, insulator units, bushing, insulators and to other fittings under all flashover conditions.

The guard rings or arcing horns shall be of substantial design in order to minimize the damage to them when flashover occurs and to bear the weight of a man during cleaning operations. The gap setting proposed by the Contractor shall be approved by the Engineer.

5.15 Allowance for Damage, Breakage and Loss

The Contractor shall supply not less than 5 per cent of the net requirements for insulators, hardware and fixing devices as an allowance for damage, breakage and loss during erection.

5.16 Phase Identification

Coloured discs shall be installed to identify phases. Black letters on the following background colours shall be used:

Phase R - Red

Phase S - Yellow

Phase T - Blue

Discs shall be installed on one set of structures at the following locations:

(a) On the main bus, midway between taps;

(b) On the bus, at line or transformer tapping;

(c) On the line entry gantry;

(d) On the transformer gantry;

(e) Each circuit breaker;

(f) Each transformer and reactor.


5.17 Junction Boxes and Kiosks

The Contractor shall supply for each circuit breaker and approved marshalling kiosk to which allow connections from the switchgear will be run.

All junction boxes, terminal boxes and marshalling kiosks shall be constructed of steel or cast iron.

All main equipment shall be arranged so that it is accessible from the front of the box or kiosk.

Outdoor boxes and kiosks shall have sloped double roofs and shall be of weatherproof, vermin-proof and termite-proof construction, with adequate ventilation and draining facilities. They shall be so designed so that condensation shall not affect the insulation of the internal apparatus, the terminal boards or the cables. Where necessary, heaters shall be provided and shall be controlled by means of a water-tight switch mounted on the outside of the box or kiosk.

Any internal divisions between compartments inside the boxes or kiosks shall be perforated to assist the natural air circulation.

Access shall be provided at both the front and back of kiosks and junction boxes, except for small terminal boxes of the type normally employed for wall mounting.

Doors and access covers shall be easily opened and shall not be secured by nuts and bolts. Doors and covers under 13-kg weight may be of the slide-on pattern; over this weight they shall be hinged.

Kiosk doors shall be fastened with integral handles rather than loose keys, and provision shall be made for padlocking each door.

Where 380, 220 or 110 volt connections are taken through a box or kiosk, they shall be adequately screened or insulated and labelled in accordance with the Specification.

All cables shall enter boxes and kiosks at the base through separate cable glands.

Plates for supporting cable glands shall be at least 450 mm above ground level. Cable glands and conduits will project at least 20mm above the gland plate to prevent any moisture on the plate draining into cables or conduits. Also, means shall be provided to drain water off the surface of the gland plate. The back, sides and front of the box or kiosk shall project at least 50mm below the gland plate to prevent moisture draining on to the plate and cable glands at any time.

5.18 Outdoor support structures and landing gantries

The requirements for lattice steel support structures for equipment and line landing gantries are provided in the civil specification.

5.19 Interlocking Equipment

The interlocking requirements are specified in the Interlocking Equipment clause of the GIS section of this specification.


6. TRANSFORMERS AND REACTORS


The extent of supply of this specification shall consist of the design, manufacture, testing, supply, delivery to site, off loading, installation and oil filling, site testing, commissioning and placing in successful operation and warranty period of the works of 400/132 kV auto transformers and associated earthing/auxiliary transformers and 400 kV shunt reactors.

6.2 Reference documents

IEC 60076-1 Power transformers - General.

IEC 60076-2 Power transformers -Temperature rise.

IEC 60076-3 Power transformers - Insulation levels, dielectric tests and external clearances in air.

IEC 60076-5 Power transformers - Ability to withstand short circuit.

IEC 60076-10 Power transformers - Determination of sound levels.

IEC 60137 Insulated bushings for alternating voltages above 1000 V.

IEC 60214 On-load tap-changers.

IEC 60354 Loading guide for oil-immersed power transformers

IEC 60529 Degrees of protection provided by enclosures

IEC 61639 Direct connection between power transformers and gas-insulated metal-enclosed switchgear for rated voltages 72.5 kV and above.

IEC TS 60859 Cable connections for gas-insulated metal-enclosed switchgear for rated voltages 72.5 kV and above:

- Fluid-filled and extruded insulation cables

- Fluid-filled and dry type cable-terminations

NEMA TR1 Transformers, regulators and reactors [for audible sound levels]

The technical data schedules for the specified transformers are included in Schedule D

6.3 Type

The auto transformer shall be outdoor type single phase units with on-load tap-changer. The external cooling medium shall be air. The insulation shall be graded for operation with effectively earthed neutral. The transformers shall comply with the requirements of the schedules and standards listed above and other relevant IEC standards. Any ambiguity shall be referred for clarification at the time of tendering


6.4 General

The transformers shall be suitable for continuous operation on a three-phase 50 Hz high voltage transmission system as specified in the Technical Schedules.

All windings of the transformers shall be capable of withstanding short circuit for the periods of time specified in IEC 60076 when operating on any tapping position, including that corresponding to minimum effective impedance, with the fault current available at the terminals. It shall be assumed that the rated voltage will be maintained on one side of the transformer when there is a short circuit between phases or to earth on the other side. The Contractor shall demonstrate the transformer and reactor’s ability to withstand the specified short circuit conditions in accordance with IEC 60076-5.

Transformers and reactors shall meet the latest stage of development reached in design, construction and materials.

Irrespective of the direction of power flow, all transformers shall be capable of operating continuously without injurious heating when delivering the specified winding currents under conditions of continuous operation with voltages higher than tapping voltages.

Transformers shall be suitable for cyclic overloading and long-time emergency loading duties in accordance IEC 60354.

Ratings shall be based on the average winding temperature rise, as measured by resistance, of 55°C and the top oil temperature rise, as measured by thermometer, of 50°C with a cooling air maximum temperature of 50°C.

The transformers shall be designed to ensure that leakage flux does not cause overheating in any part of the transformer.

The design and manufacture of the transformers, reactors and auxiliary plant shall be such that the noise level is a minimum and that the level of vibration does not adversely affect any clamping or produce excessive stress in any material. Noise levels shall be measured in accordance with IEC 60551. The maximum acceptable level is 88 dB in conformity with NEMA standard TR-1.

The transformers and reactors shall be designed with particular attention to the suppression of harmonic currents, especially the third and fifth, so as to minimise interference with communications circuits.

The transformers shall be designed to operate satisfactorily in parallel when in the same tap position. The transformers and all associated facilities (e.g. tap-changer) shall have the ability to withstand the effects of short-circuit currents, defined as symmetrical short circuit current in the Technical Schedules, when operating on any tapping position according to requirements of IEC 60076-5.


All metal parts of the transformer with the exception of the individual core laminations, core bolts and associated individual side plates shall be maintained at the same fixed potential. The earthing structure shall be designed to carry, without damage, the maximum possible earth fault current for a duration of at least equal to the short circuit withstand period of the main windings. The design and manufacture of the transformers and auxiliary plant shall be such that the noise level is at a minimum and that the level of vibration does not adversely affect any clamping or produce excessive stress in any material. The transformer manufacturer shall supply sufficient information to the civil works contractor to ensure adequate design of the transformer mounting structure.

6.5 Tertiary windings

The tertiary winding of the transformer is required for the purpose of suppressing harmonics and of providing a connection for reactive (capacitive or inductive) compensation equipment and for a connection to an earthing transformer to provide an earth and an auxiliary supply as required by site and system conditions.

The 11 kV tertiary shall be designed to be capable to a rating of 75MVA.

The winding shall be capable of withstanding the forces to which it is subjected under all conditions, particularly the forces due to a short circuit between terminals or between any terminal and earth, with full voltage maintained on all other windings intended for connection to external sources of supply and allowing for any feed back through windings connected to rotating machines.

Suitable surge arresters are to be provided to protect the winding against overvoltage. If the winding is connected by cable the surge arresters shall be mounted in the disconnecting chamber.

6.6 Loss Evaluation

For the purposes of tender evaluation the transformer and reactor losses are capitalized in the following manner:

Transformers

No-load loss (NLL) 2932 US$/kW at rated voltage

Load loss (LL) 688 US$/kW at rated MVA and voltage

Reactors

No-load loss 2932 US$/kW at rated voltage

Capitalisation (PV) Price initial cost + NLL + LL

Guaranteed losses are declared in Schedule M


6.7 Penalties

The tolerance permitted is +10% of the total declared losses; being the sum of the load and no load losses excluding cooling system consumption.

Any transformer or reactor with losses more than +10% of the total declared loss will be rejected, unless otherwise agreed by the Engineer.

For transformers or reactors with total losses within +5% of the declared losses no variation of the contract price will be made.

For transformers or reactors where the total evaluated losses are between +5% to +10% of the total declared losses the contract price will be reduced by the total evaluated cost of losses in excess of the evaluated cost of the guaranteed losses.

For any transformer or reactor with total losses less than 100% of the guaranteed losses , no variation of the Contract price will be made.

6.8 Magnetic circuits

Particular care shall be taken to secure even mechanical pressure over the whole of the core laminations. Each lamination shall be insulated with a material that will not deteriorate under pressure and the action of hot oil.

Where the magnetic circuit is divided into packets tinned copper strip bridging pieces shall be inserted to maintain electrical continuity between packets.

The transformer core shall be free from over fluxing liable to cause damage or to cause mal-operation of the protection equipment when operating under the continuous overvoltage condition specified in the Schedules. Under this steady overvoltage condition the maximum flux density must not exceed 1.9 tesla and the magnetising current must not exceed 5 per cent of the rated load current at normal rated voltage.

The core shall be manufactured of high grade, high permeability, grain orientated, non-aging sheet steel laminations having smooth surfaces. The core and all insulation associated with the core shall be designed so that no detrimental changes in physical or electrical properties will occur during the life cycle of the equipment.

The cores, framework, clamping arrangements and general structure of the transformers and reactors shall be capable of withstanding any shocks to which they may be subjected during transport, installation and service. Adequate provision shall be made to prevent movement of internal parts of the transformers and reactors relative to the tank, to support the core structure in the tank and to carry the weight of the core and windings when suspended.


6.9 Windings

Winding insulation and all non-metallic material used in winding stacks shall be so designed, installed and treated such that no further shrinkage shall take place after assembly.

The windings shall be formed using copper conductor. All permanent connections shall be brazed. All other connections shall be of a compression type with multi-bolt connections.

Coils shall be constructed to avoid abrasion of the insulation, (e.g. on transposed conductors), allowing for the expansion and contraction set up by changes of temperature or the vibration encountered during normal operation. The insulation on the conductors between turns shall be of paper.

The windings shall be designed to reduce to a minimum the out-of-balance forces inherent in the transformer. Tappings shall be arranged at such positions on the windings as will preserve, as far as possible, electro-magnetic balance at all voltage ratios.

Tappings shall not be brought out from the inside of a coil nor from intermediate turns.

The windings and connections shall be braced to withstand shocks, which may occur during transport or due to switching or other transient conditions during service.

Where the yoke supporting channels are adapted for taking up shrinkage in the windings, the arrangement shall be such as to throw a minimum amount of stress on any core bolt insulation.

If the winding is built up of sections or disc coils, separated by spacers, the clamping arrangements shall be such that equal pressure is applied to all columns of spacers. All such spacers shall be securely located and shall be of suitable material.

6.10 Internal earthing arrangements

All metal parts of the transformers and reactors with the exception of the individual core laminations, core bolts and associated individual side plates shall be maintained at some fixed potential.

The magnetic circuit shall be earthed to the clamping structure at one point only through a removable link with a captive bolt and nut accessibly placed beneath an inspection opening in the tank cover. The connection to the link shall be on the same side of the core as the main earth connection, and taken from the extreme edge of the top yoke in close proximity to the bridging pieces. Alternatively the core earth connection may be brought out through a bushing for earthing to the outside of the tank, in close proximity to the main yoke clamping structure earth point.

Where coil-clamping rings are of metal at earth potential each ring shall be connected to the adjacent core clamping structure on the same side of the transformer or reactor as the main earth connection.

The main yoke clamping structures shall be connected to the tank body by a copper strap located at the top of the tank. If there is no metal-to-metal contact between the top and bottom clamping structure, the latter shall be earthed.


Core clamping structures having an insulated sectional construction shall be provided with a separate link for each individual section.

All earthing connections with the exception of those from the individual coil clamping rings shall have a cross-sectional area of not less than 80 mm². Connections inserted between laminations shall have a cross-sectional area of not less than 20 mm².

6.11 Tanks

Transformer and reactor tanks shall be of welded steel and designed to allow the complete transformer or reactor, when arranged for transport, to be lifted by crane and transported without overstraining any joints and without causing subsequent leakage of oil. Each tank shall be provided with a minimum of four jacking lugs, to enable the transformer or reactor, complete with all tank mounted accessories and filled with oil, to be raised or lowered by jacks. The jacking points shall be not less than 300 mm above base level for transport masses up to 10 tonnes and not less than 700 mm for greater transport masses. Facilities shall also be provided to enable the transformer or reactor to be hauled or slewed in any direction.

The base of each tank shall be so designed that it will be possible to move the complete transformer or reactor in any direction without injury when using rollers, plates or rails. A design, which necessitates either slide, rails being placed in particular positions or detachable under bases shall not be used.

The base shall be designed to permit moving the assembled and oil-filled transformers on rollers. Length and spacing of each pair of reinforced parallel rolling areas shall be such that the fully assembled transformers, with or without oil, can be safely tilted 15 degrees. Internal reinforcing shall not prevent draining of all oil from the tank.

The transformers shall be fitted with jacking steps having a suitable clearance from the underside of step to bottom of base. The steps shall have a free surface for the head of the jack. Location of steps shall permit used of jacks without fouling any part of the transformer or shipping skids paralleling either axis. The arrangement of jacking steps and base members shall be such that the transformer can be safely jacked, using a pair of steps parallel to either axis. Each jacking step shall have capacity for lifting one half of the completely assembled transformer filled with oil.

The wheels must be suitable for a standard track (1.435 metre between inside of rail heads). The when the tank is jacked up clear of the rails or floor.

Means shall be provided for locking the swivel movement in positions parallel to and at right angles to the longitudinal axis of the tank.

The wheel loading shall not exceed 13,600 kg and the spacing between the wheels shall not exceed 1.7 metres, flanged wheels will be arranged so that they can be turned through an angle of 90 degrees

The transformers shall also be supplied with eyes for attaching hauling equipment, located in a position acceptable to the Engineer.


The main tank body, tap changing compartments, radiators and coolers, shall each be capable of withstanding, when empty of oil, one atmosphere vacuum filling with oil in the field. It shall also be capable of withstanding positive pressures of 0.35 kg/cm2 or, 125 per cent of maximum oil pressure whichever is greater vacuum test level. The plate thickness for the tank sides shall be a minimum of 6 mm.

Tank stiffeners and mounting brackets shall be continuously welded to the tank.

Wherever possible, the transformer or reactor tank and its accessories shall be designed without pockets wherein gas may collect. Where pockets cannot be avoided, pipes shall be provided to vent the gas into the main expansion pipe. The vent pipes shall have a minimum inside diameter of 20 mm and, if necessary, shall be protected against mechanical damage.

All joints other than those, which may have to be broken, shall be welded. Caulking of defective welded joints will not be permitted. Such defective joints may be re-welded subject to the written approval of the Engineer.

Gaskets of synthetic rubber or neoprene-bonded cork are not permitted. When installed in position, the outer edges shall be protected by metal-to-metal stops of fire-resistant stop gasket material.

Tank covers shall not permanently distort when lifted. Inspection openings of ample size shall be provided to give easy access to bushings, for changing ratio or winding connections, and for testing the earth connections. Inspection covers shall be provided with lifting handles. The tank cover shall be fitted with a thermometer pocket, with captive screwed cap, located in the position of maximum oil temperature at continuous maximum rating.

It must be possible to remove any bushing without removing the tank cover.

A pressure relief device of sufficient size capable of functioning without electrical power, shall be provided for the rapid release of any pressure that may be generated within the tank and which might result in damage to the equipment, but it shall be capable of maintaining the oil tightness of the transformer or reactor under all conditions of normal service. The device shall operate at a static pressure of less than the hydraulic test pressure for transformer or reactor tanks and shall be designed to prevent further oil flow from the transformer or reactor following its operation. In the event that the device is a spring operated valve type it shall be provided with one set of normally open contacts, which will be used for tripping purposes.

The relief device shall be mounted on the main tank and if mounted on the cover it shall be fitted with a skirt projecting inside the tank to prevent an accumulation of gas within the device.

Terminals shall be provided close to each corner at the base of the tank for earthing purposes.

The following plant information plates shall be fixed to the tank at an approximate height of 1.75 m above the ground level: -

(a) A rating plate bearing the data specified in IEC 60076 or IEC 60289.


(b) A diagram plate on which the transformer tapping voltages in kilovolts shall also be indicated for each tap, together with the transformer impedances at minimum and maximum voltage ratios and for the principal tapping.

(c) A property plate of approved design and wording.

(d) A title plate.

(e) A valve location plate showing the location and function of all valves, drain and air release plugs and oil sampling devices.

6.12 Bushings

6.12.1 Oil/SF6 Bushings Oil/SF6 bushings shall be designed in accordance with the requirements of IEC 61639, IEC 60137, IEC 60076 and IEC 62271.

Transformers may be subjected to overload duties in accordance with IEC 60354 and the bushings shall be suitably designed and rated to accommodate these overload duties.

To ensure satisfactory jointing of the flanges of the GIS trunking with the flanges of the HV and LV transformer bushings the maximum permitted tolerances on relevant dimensions of the transformer, taking the centre of the turret as the datum point, shall be as stated in the table below. These tolerances shall be applicable to the transformer in its on-site position after any necessary processing and when fully filled with oil.

Relevant Dimensions

(a) Between HV turrets and LV turrets ±20 mm

(b) From turrets to longitudinal centre line of tank ±15 mm

(c) From top of turrets to corresponding point on,

(i) The edge of the tank base ±20 mm

(ii) The plinth or floor ±25 mm

(d) Level of top of turrets ±1.0°

The bushing flange shall be insulated from the transformer tank to allow a test voltage of 5 kV rms for one minute to be applied between each bushing flange and transformer tank.

In service the bushing flange will be connected to the same substation earth mat as the transformer tank. The bushing flange should be earthed during all testing except for the flange insulation test described above.


The internal and external arrangements of the transformer shall be designed to permit the fitting of either oil/SF6 or oil/air bushings on-site without the need for factory modifications. If any additional parts are required to allow a change of bushing then these should be fully designed at the outset. However, these parts are not normally required to be supplied with the transformer but if needed will be requested by the Engineer.

The oil end of the oil/SF6 transformer bushing will be suitably dimensioned to accommodate current transformers, the number and dimensions of which will be specified by others

Oil/SF6 bushings of the oil impregnated design shall be fitted with a suitable pressure gauge and switch to give indication and alarm facilities in the event of,

(i) Leakage of SF6 gas from the GIS trunking into the self-contained bushing oil.

(ii) Loss of oil from the bushing

The switch(s) shall be capable of giving an alarm at abnormally low or abnormally high operating pressure of the internal bushing zone. The switches shall comply with the requirements of IEC 60255-13 category III. Alarm pressure settings shall be appropriate to the bushing design and its application.

Oil/SF6 bushings connected to GIS trunking shall comply with the temperature rise criteria of IEC 60157, operating at the GIS rated temperature limit as specified in IEC 62271 - 203.

6.12.2 Oil/Air Bushings Oil/air bushings shall be designed in accordance with the requirements of IEC 60137.

Transformer bushings for 132 kV and above shall be either of the oil impregnated paper or resin impregnated type. When filled with transformer oil there shall be no connection with the oil in the transformer and an oil gauge shall be provided. The visible oil levels in the gauge shall correspond to average oil temperatures from the minimum ambient stated in the Schedules to plus 90°C. The oil levels at 15°C and 35°C shall be marked. Connections from the main windings to bushings shall be flexible and shall be such that undue mechanical stresses are not imposed on them during assembly on site.

Bushings shall be mounted on the tank in such a manner that external connection can be made free of all obstacles. Neutral bushings shall be mounted in position from which a connection can be made to a neutral current transformer mounted on a bracket secured to the tank. The switchgear manufacturer will supply the current transformer but provision shall be made on the tank for mounting to the Engineer’s requirements.

6.12.3 Terminations The terminations shall be designed to suit the position and connection of the transformer as shown on the attached drawings listed in Schedule E.


MOE standardise on the size of cables used on connections between transformers and switchgear and typically the cables shall be of XLPE single core type and according to the following sizes:

132 kV side 800 sq. mm (A1) 33 kV side 400 sq. mm (Cu) 11 kV side 400 sq. mm (Cu)

In principle the full rating of the transformers is to be achieved and if the above cables are not sufficient then it is normal practice to increase the cable capacity by the addition of (3) of single core cable of the same size.

Neutral bushings will be suitable for connection to an external bus or conductor. There shall be no connection of the neutral to the inside of the tank.

The details of the connections to all terminals will be confirmed after award of contract.

6.13 Conservator Vessels, Oil Level Gauges and Breathers

Each conservator shall have a filling cap, an adequate sump and be so designed that it can be completely drained by means of a drain valve. One end of the conservator shall have a removable end cover, complete with integral lugs for lifting purposes and secured by nut and bolt fixings, to permit internal cleaning of the conservator.

Where conservator tanks are mounted on the separate coolers, a flexible stainless steel piece (expansion joint) shall be included in each oil pipe connection between the transformer or reactor and the conservator tank.

An oil level gauge shall be provided for each conservator. The indicated minimum oil level shall occur when the feed pipe to the main tank is covered with not less than 12 mm depth of oil. The indicated oil level range shall correspond to average oil temperatures from the minimum ambient to plus 90°C. The oil levels at 15°C and 35°C shall be marked on the gauge. The oil level gauge shall incorporate alarm contacts, which close when the oil level falls below a predetermined level.

Taps or valves shall not be fitted to oil gauges.

The main oil feed pipe from the conservator vessel to the transformer shall be connected to the highest point of the tank and shall be arranged at a rising angle towards the conservator of from 3 to 7 degrees to the horizontal. A valve shall be provided at the conservator to cut off the oil to the transformer.

Whether or not the oil is in direct contact with air or gas the air outlet from each conservator vessel shall be connected to a dehumidifying breather, which shall be mounted at approximately 1.4 m above ground level. This breather should be designed taking into account the ambient operating temperatures and should be at least one size larger than would be fitted for use in a temperate climate.


Where a conservator vessel contains two compartments, one for oil in the main tank and the other for the oil associated with the current making and breaking contacts of the tap change equipment, there shall be no communication between the two compartments in respect of the oil and air spaces. Each compartment shall be provided with the fittings detailed in the preceding paragraphs as if it were a separate conservator vessel.

6.14 Valves

Valves shall be of the fully sealing full-way type and shall be opened by turning counter-clockwise when facing the hand wheel. They shall be suitable for working between the minimum ambient and the maximum oil temperatures stated in the Schedules.

Padlocks shall be provided for locking all valves other than individual radiator valves in the "open" and "closed" positions. Valves shall be provided with an indicator readily visible from ground level, to show clearly the position of the valve.

All valve handwheels shall be fitted with nameplates, which shall be chromium plated brass not less than 3 mm thick with the engraving filed with enamel. All valves shall be fitted with spoked handwheels, the spokes and rims of which shall be smooth and where necessary, for appearance, shall be chromium plated.

All valves opening to atmosphere shall be fitted with blanking plates.

Each transformer and reactor tank shall be fitted with the following: -

(a) One 100 mm valve at the top and one 100 mm valve at the bottom of the tank mounted diagonally opposite each other, for connection to oil circulating and oil filtering equipment. The lower valve shall also function as a drain valve.

(b) An oil sampling device at the top and bottom of the main tank.

(c) All parts containing oil, and liable to trap air during filling, shall be fitted with a flanged type air release plug at their highest points.

6.15 Cooling Plant

Transformers shall have ONAN/ONAF/OFAF cooling options and facilities shall be provided at the marshalling kiosk or cubicle for the selection of AUTOMATIC or MANUAL control of the cooling plant motors.

Reactors shall be ONAN cooled.

Transformers shall be fitted with sectionalised cooling banks necessary to meet the continuous maximum rating (CMR). The Contractor shall be responsible for designing the optimum number of sections to meet the CMR and fit a spare section. CMR is to be available with the loss of one section of radiators and associated fans and pumps without depending on the overload capability of the transformer.


Transformers shall be capable of remaining in operation at full load for 20 minutes in event of failure of the cooling fans and for 10 minutes in the event of failure of the oil circulating pump without the calculated winding hot spot temperature exceeding 150°C. Failure of one fan in each group of fans shall not reduce the continuous maximum rating of the transformer.

Radiators and coolers shall be designed so that all painted surfaces can be readily cleaned and subsequently painted in position.

Detachable radiators and separate cooler assemblies connected to the main tank shall be provided with machined flanged inlet and outlet pipes.

Plugs shall be fitted at the top and bottom of each radiator for filling and draining.

Mal-operation of gas and oil actuated relays shall not occur on starting or stopping of forced-oil circulation.

The oil circuit of all coolers shall be provided with the following as appropriate to tank mounted or separate bank coolers: -

(a) A valve at each point of connection to the transformer or reactor tank.

(b) Isolating valves at the bottom of each individually detachable radiator. The valves shall be located on header side of the radiator attachment point.

(c) A valve in the main oil connection at the bottom of each cooler in addition to those mounted on the tank.

(d) Loose blanking plates to permit the blanking off of the main oil connection to the top of each cooler.

(e) A 100 mm oil filtering valve at the top and bottom of each cooler, the bottom valve shall also function as a drain valve.

(f) A thermometer pocket fitted with a captive screwed cap on the inlet and outlet oil branches of each cooler.

(g) Visual oil flow indicators in the pipework adjacent to the coolers. In the event that this will offer impedance to oil flow under ONAN conditions a differential pressure gauge of approved design and manufacture may be connected across the pumps, as an alternative.

The material of the tube plates and tubes shall be such that corrosion shall not take place due to galvanic action.

Where separately mounted cooling equipment is provided a flexible stainless steel piece (expansion joint) shall be included in each oil pipe connection between the transformer or reactor and the oil coolers.


Drain plugs shall be provided in order that each section of pipework can be drained independently.

Each forced oil cooler shall be provided with a fully weatherproof motor driven oil pump. The motor shall be of the submersible type. It shall be possible to remove the pump and motor from the oil circuit without having to lower the level of the oil in the transformer or coolers.

Where forced air cooling is provided it shall be possible to remove the fan, complete with its motor and supporting structure without disturbing or dismantling the cooler framework or pipework.

Wire mesh guards galvanized after manufacture shall be provided to prevent accidental contact with the fan blades. Metal guards shall also be provided over all other moving parts. The guards shall be designed such that neither the blades nor other moving parts can be touched by a Standard Test Finger to IEC 60529.

6.16 Cooler Control

Each motor or group of motors shall be provided with a three-pole electrically operated contactor and with control gear of approved design for starting and stopping manually.

Where forced cooling is used on transformers, provision shall be included under this contract for automatic starting and stopping from contacts on the winding temperature indicating devices. The control equipment shall be provided with a short time delay device to prevent the starting of more than one motor, or group of motors in the case of multiple cooling, at a time.

Where motors are operated in groups the group protection shall be arranged so that it will operate satisfactorily in the event of a fault occurring in a single motor.

The control arrangements are to be designed to prevent the starting of motors totalling more than 15 kW simultaneously either manually of automatically. Phase failure relays are to be provided in the main cooler supply circuit.

All contacts and other parts, which may require periodic renewal, adjustment or inspection, shall be readily accessible.

All wiring for the control gear accommodated in the marshalling kiosk together with all necessary cable boxes and terminations and all wiring between the marshalling kiosk and the motors shall be included in the contract.

Two independent sources of power shall be made available to ensure loss of cooling capacity for a single contingency is not greater than 50 per cent. 6.17 On-load Tap Changing Equipment

Each transformer shall be equipped with an on load tap changer suitable for the rated current (+20% overload) of modern design and robust construction of MR Type from Germany for varying the turns ratio without producing phase displacement. Tappings shall be brought out from the neutral end of the common part of the windings. The equipment shall vary the turns ratio without producing phase displacement.


All leads and connections to fixed and moving contact assemblies and between the transformer and the voltage control device shall be supported and adequately braced to withstand the short circuit current for which the associated transformer is designed.

Equipment for varying the effective turns ratio on-load shall consist of tap changing gear arranged for local hand and electrical operation and remote electrical operation. On load tap changers shall comply with IEC 60214, IEC 60542 and with the requirements of this specification. It shall also be so designed that it may be easily adapted to operate by automatic control.

The tap changing switches and mechanism shall be mounted in an accessible position in oil tanks or compartments and shall be supported in the main tank, from the main tank or from its base. It is preferable that examination and repair of both selector and diverter switches including their associated equipment should be carried out without lowering the oil level in the main tank. However, designs of tap-changer that involve lowering the oil level in the transformer tank may be accepted with the agreement of the Engineer.

It shall not be possible for the oil in those compartments of the tap change equipment which contain contacts used for making and breaking current, to mix with the oil in the main transformer or with the oil in the compartments containing contacts not used for making or breaking current. A drain valve shall be provided.

The oil in those compartments of the main tap-change apparatus that do not contain contacts used for making or breaking current shall be maintained under conservator head by means of a pipe connection from the highest point of the chamber to the conservator. This connection shall be controlled by a suitable valve and shall be arranged so that any gas leaving the chamber will pass into the gas and oil actuated relay.

Each compartment in which the oil is not maintained under conservator head shall be provided with an oil gauge.

Any enclosed compartment not oil filled shall be adequately ventilated and designed to prevent the ingress of vermin. All contactors relay coils or other parts shall be suitably protected against corrosion or deterioration due to condensation.

Tap changing shall be prevented when the transformer is carrying a load above a predetermined maximum or when on short circuit. Tap changing equipment however, shall be suitably rated for operation when transformers are subjected to overload duties in accordance with IEC 60354.

Limit switches shall be provided to prevent over-running of the mechanism and shall be directly connected in the circuit of the operating motor. Limit switches may be connected in the control circuit of the operating motor provided that a mechanical de-clutching mechanism is incorporated.

A mechanical stop or other approved device shall be provided to prevent over-running of the mechanism under any condition without resulting damage.


Thermal devices or other approved means shall be provided to protect the motor and control circuits. Switches for the initiation of a tap change shall bear the inscription "Raise Tap Number", as applicable.

Tripping contacts associated with any thermal device used for the protection of tap changing equipment shall be suitable for making and breaking 150 VA at 0.35 power factor, between the limits of 30 and 250 volts ac or breaking 150 VA and making 500 VA between the limits of 110 and 250 volts dc.

A hand crank for manual operation of the tap-changer driving mechanism shall be provided and shall include the necessary interlocking between manual and electrical operation. Suitable local storage for the hand crank shall be provided

A device shall be fitted to the tap changing mechanism to indicate the number of operations completed by the equipment.

A permanently legible lubrication chart shall be fitted within the driving mechanism chamber.

The terminals of the operating motor shall be clearly and permanently inscribed with numbers corresponding to those on the leads attached thereto.

Equipment for local and remote electrical and local hand operation shall comply with the following conditions: -

(a) It shall not be possible to operate the electric drive when the hand operating gear is in use.

(b) It shall not be possible for any two electrical control points to be in operation at the same time.

(c) Each step movement shall require separate initiation at the control point.

(d) All electrical control switches and the local operation gear shall be clearly labelled in an approved manner to indicate the direction of tap changing.

(e) The local control switches shall be housed in the tap changer drive mechanism cubicle or the transformer marshalling kiosk.

The equipment shall be arranged so as to ensure that when a step movement has been commenced it shall be completed independently of the operation of the control relays or switches. If a failure of the auxiliary supply during a tap change, or any other contingency, would result in that movement not being completed, means shall be provided to safeguard the transformer and its auxiliary equipment.

The equipment shall give indication mechanically at the transformer and electrically at the remote control points of the tapping in use. The indicator at the transformer shall show the number of the tap in use and the indicator at the remote control points shall show clearly the actual voltage ratio in kilovolts and the tap number representing this ratio. The numbers shall range from 1 upwards.


The equipment shall give indication at the remote control points that a tap change is in progress. This may be by means of an illuminated lamp and alarm buzzer if the Substation Control Point is a panel. If the tap change is not completed in its specified time the alarm shall remain permanent until the tap change is completed.

When operating in parallel with other transformers, an adequate interlocking device shall be provided for synchronous operation of the tap-changer. The equipment shall give an indication at the remote control points as described above when the units of a group of transformers arranged to operate in parallel are operating at different ratios. It shall not operate under any control arrangement other than parallel control.

On-load tap changing equipment shall be suitable for supervisory control and indication. Both a separate multi-way switch, having one fixed contact for each tap position and a 0 – 5 mA signal representing the tap position shall be provided for this purpose and wired to the marshalling kiosk or cabinet.

6.17.1 Automatic and Manual Voltage Control The on-load tap changing equipment shall be fully automatic, and an automatic voltage control relay (AVC) shall be provided. The relay shall be responsive to variation in the measured voltage and cause the necessary tap change to be made to restore the voltage to the desired level within pre-determined limits. The AVR shall operate the transformers connected to each electrically separate busbar in groups, on a busbar by busbar basis.

The recommended preset range for 400/138.6 kV transformers is between 125.4-138.6 kV and for 132/33/11.5 kV transformers is between 10.5-11.5 kV. Where 132 kV transformers have dual voltage l.v windings, the 11.5lV voltage shall be monitored. Where transformers may have their l.v windings connected in parallel, the AVR will need to be able to control all such transformers as a co-ordinated function.

The voltage control equipment shall be suitable for control of up to a specified maximum number of transformers in parallel. Initially it may be required to control less than the maximum transformers, but it shall be possible to extend the facilities to cover up to the maximum transformers at a later date. For 400/136.8 kV transformers, the maximum shall be four. For 132/33/11.5 kV transformers, the maximum shall be three.

The following facilities shall be provided with the AVR:

Function Controlled from

Tap Raise and Lower National Control Centre or Substation Control Point for the transformers in each busbar group, and the Transformer Tap Changer Mechanism/Marshalling Kiosk, for each transformer individually when in LOCAL

Tap Changer Auto/Manual National Control Centre or Substation Control Point, for each busbar group- Manual control


shall be possible when the MANUAL/AUTO switch is in MANUAL position, and automatic facilities shall be inhibited

Tap changer Local/Remote The Transformer Tap Changer Mechanism/ Marshalling Kiosk

AVR point of control National Control Centre or Substation Control Point, for station AVR facilities

Target Voltage Set Point National Control Centre or Substation Control Point for each separate or interconnected busbar group

AVC relays equipped to accept electrical signals to control the actual set point shall be capable of set point adjustment in steps not exceeding 1 per cent.

Failure of the AVR should keep the tap-changer in position and give an alarm.

A full description of the AVR and its functions shall be submitted with the Tender.

The voltage control and parallel operation schemes and their complete analysis and design shall be the responsibility of the Contractor.

The AVR functionality may be embedded in the Substation Control System, if the Tenderer can provide satisfactory evidence of its successful implementation in a similar environment to Iraq. If the AVR functionality is provided by a separate AVR relay and controlled from the SCS, the Contractor shall be responsible for supplying all of the equipment and integrating these into a complete working system and shall comprise, in general, but not limited to the following:

(a) Control switches, pushbuttons, tap-position indicator, alarms and indications.

(b) AVR panels/cubicles complete with all the necessary interposing and auxiliary relays for voltage control.

(c) The AVR panel shall be located in the Control/ Relay Room.

The functionality of the AVR shall be subject to the approval of the Engineer.

Approved means, either by switch or links, shall be provided for each transformer to give complete isolation of all electrical supplies at the SCS, and/or the AVR Panel if fitted, without preventing the operation of tap-changers on the other transformers.

The measured voltages will be derived from voltage transformers, having secondary windings rated at 110 volts phase-to-phase and having an accuracy not inferior to Class 1. The relay shall have a nominal voltage rating equal to the VT secondary winding rating.


The relay setting voltage, expressed as a percentage of the relay nominal voltage shall be adjustable over a range of not less than 10 per cent of nominal.

The relay sensitivity band relative to the setting voltage shall be adjustable from not more than 1.5 times to not less than 2.5 times the percentage equivalent of one tap change step.

Settings for relay operating time shall be adjustable. For definite time relays, the setting range shall be from 10 s to 120 s and the timing device shall be of the "slow resetting" type. Relays having time dependent characteristics shall have a range of adjustments allowing a delay of up to at least 120 s for a voltage deviation 1 per cent greater than the sensitivity setting and not more than 10 s for a deviation of 5 times sensitivity or 10 per cent voltage, whichever is the greater.

The relay shall be insensitive to frequency variation between the limits of 47 Hz and 51 Hz and shall incorporate an undervoltage blocking facility to render the control inoperative if the reference voltage falls to 80 per cent of nominal value with automatic restoration of control when the reference voltage rises to 85 per cent of nominal value.

The relay setting voltage must be capable of adjustment from the remote and supervisory locations. When selected to either supervisory or remote and selected for automatic operation the control signal shall vary the set point of the AVR relay. When selected to manual the control signal shall operate the tap changers in a busbar group directly to raise or lower the tap position as required. It shall be possible to select auto/manual control from the remote and supervisory locations.

On-load tap change transformers provided with fully automatic control and required to operate in parallel as a group, shall be provided with means to ensure proportionate sharing of watts and VARs.

Control equipment supplied under this contract shall include all alarm, indication and repeat relays necessary to identity faulted equipment. Indication of faulted equipment shall be provided at the equipment itself, and to the remote control points. All equipment shall be suitable for operation within the limits 85 per cent - 110 per cent of the auxiliary voltage supply.

On each transformer the voltage transformer supply to the voltage regulating relay shall be monitored for partial or complete failure. If the circuit breaker controlling the lower voltage side of the transformer is open or when the tap changer is on other than automatic control then any alarm or indication should be made inoperative.

6.18 Parallel operation

The transformers shall be suitable for parallel operation with other transformers of the same type and comparable ratings at rated voltage and on taps of like turn ratio. Full details of these transformers shall be made available to the Contractor for design co-ordination.


6.19 Disconnecting and sealing end chambers

Where cables for 11 kV and above are terminated in a cable box, an oil filled disconnecting chamber with removable links shall be provided for testing purposes. The disconnecting chamber shall be capable of withstanding on site the cable high voltage test level in accordance with IEC 60055 and IEC 60141 as appropriate. During the test the links in the disconnecting chamber will be withdrawn and the transformer or reactor windings earthed. A barrier shall be provided on both sides of the disconnecting chamber to prevent ingress of the oil used for filling the chamber into the cable box or tank.

Where sealing end chambers are provided, the disconnecting chamber may be omitted and the facilities for testing shall be provided in the sealing end chamber itself; a barrier shall be provided between the sealing end chamber and the main tank.

Provision shall be made to allow for the expansion of the filling medium and drain plugs of ample size shall be provided for enabling the filling medium to be removed.

The disconnecting or sealing end chambers shall have a removable cover and the design of the chambers shall be such that ample clearances are provided to enable either the transformer or reactor or each cable to be subjected separately to high voltage tests. The disconnecting links shall be flexible or flexibly attached at one end.

The oil level in disconnecting or sealing end chambers shall be maintained from the main conservator tank by means of a connection to the highest point of the chamber and this connection shall be controlled by a valve.

An earthing terminal shall be provided in each disconnecting or sealing end chamber to which the connections from the transformer or reactor winding can be earthed during cable testing.

Terminals shall be marked in a clear and permanent manner.

6.20 Temperature indicating devices, alarms and gas and oil actuated relays

6.20.1 Temperature Indicating Devices and Alarms Oil temperature indicating devices shall be fitted with alarm and trip contacts.

Winding temperature indicating devices shall indicate the temperature of the hottest spot of the winding and shall have a load-temperature characteristic approximating to that of the main winding. Alarm and trip contracts shall be provided.

Alarm contacts of oil and winding temperature indicating devices shall be adjustable over a range of 60°C to 110°C and trip contacts adjustable over a range of 80°C to 150°C. Alarm and trip contacts shall be suitable for making and breaking 150 VA at 0.35 power factor, between the limits of 30 and 250 volts ac or breaking 150 VA and making 500 VA between the limits of 110 and 250 volts dc.


For transformers having or being suitable for mixed or forced cooled ratings whether the forced cooling is to be supplied initially or at a later date, an additional contacts shall be provided to automatically control the forced cooling plant.

Temperature indicating devices shall incorporate a dial and a pointer indicator and a separate pointer to register the maximum temperature reached.

The capillary connected sensing bulbs of temperature indicators shall be positioned in separate oil-tight pockets arranged in the top oil.

Where winding temperature indicators are specified they shall be associated with one phase only. In the case of auto-transformers there shall be separate indicators for the series and common windings.

The winding temperature indicating devices shall be so designed that it shall be possible to move the pointers by hand for the purpose of checking the operation of the contacts and associated equipment. The working parts of the instruments shall be made visible by the provision of cut-away dials and glass fronted covers.

The characteristics of the winding temperature indicating devices shall be forwarded to the Engineer for approval prior to the delivery of the transformers and shall also be included in the operating and maintenance instructions.

All temperature indicators shall be housed in the marshalling kiosk or cabinet and shall be mounted so that they will not be affected by vibration.

6.20.2 Gas and Oil Actuated Relays Gas and oil actuated relays shall be fitted to each transformer and reactor and to each tap selector compartment. They shall have alarm contacts that close on collection of gas or at low oil level and tripping contacts, which close following an oil surge.

The surge float contacts shall close at a rate of steady oil flow between the following limits. As far as possible the limits shall also be met when the relay is subjected to oil surge conditions produced by rapid opening of a lever operated gate valve.

Oil Pipe Connection Internal Diameter

Operational Limits for Relay Rising Angles of 1º to 9º

mm Steady Oil Flow (mm/s)

25 700 – 1300

50 750 – 1400

75 900 - 1600

The normally open, electrically separate, alarm and tripping contacts shall not be exposed to oil.


The relays shall be fitted in the expansion pipe connecting the transformer or reactor tank to the conservator.

Each relay shall be provided with a test cock to take a flexible pipe connection for checking the operation of the relay.

A 5.0 mm inside diameter pipe shall be connected to the gas release cock of the relay and brought down to a point approximately 1.4 m above ground level where it shall be terminated by a cock.

6.21 Oil Flow Indicators

Forced oil cooled transformers shall be provided with a visual oil flow indicator in each outlet pipe connection from the coolers. These indicators shall incorporate contacts, which close under conditions of no oil flow.

6.22 Current transformers

If specified each transformer shall be equipped, with multi-ratio type current transformers, which shall conform to the requirements of IEC 60344-1

The current transformer shall be used in balanced-current protection schemes and will be suitable for this duty. Further information will be made available during the course of the contract.

6.23 Surge protection

The main transformers windings and neutral points are to be protected against incoming surges on both the HV and LV side by means of lightning arresters located as close as possible to the respective bushings. Generally the lightning protection arresters will be supplied in the Substation part of a contract.

6.24 Condition Monitoring System

When specified the Contractor shall provide as an optional cost for the transformer to be equipped with an on line monitoring system to provide condition assessment.

Typically measurements shall be used to derive the following data: -

Hot spot temperature in accordance with IEC 60354 Ageing rate in accordance with IEC 60354 Continuous overload current capacity of the transformer. Overvoltage detection including a lightning surge and overcurrent. Variation in the capacitance of bushings.

The monitoring system shall be capable of recording the following quantities: -

Measurement of current and voltage on the HV and tertiary winding. Top oil temperature. Moisture in the oil. Gas in the oil by means of a Hydran unit or similar.


Tap change position and number of tap change operations. Status of fans and pumps Tap changer motor power requirement.

The system may be used to control the operation of the pumps and coolers as required given the ambient temperature and transformer loading conditions.

All necessary sensors in addition to those already specified shall be supplied with the transformer.

The monitoring unit shall be mounted in the transformer marshalling kiosk and be suitable for outdoor operation.

The monitor shall be co-ordinated into the substation SCS system and be suitable for connection to a fibre optic LAN system and provide remote monitoring data to National Control Centre as required. Data shall be recorded locally and date stamped from the substation GPS time system.

6.25 Transformer Oil

The transformer oil shall comply with the requirements of IEC 60296. The oil shall be a highly refined oil suitable for use as an insulating and cooling medium in transformers and reactors. For information Shell Diala “B” and Nynas Nitro GBN10 oils have been used on the existing M.O.E. equipment.

The transformers shall be shipped filled with gas and sufficient gas bottles are to be connected during transit. The transformer shall be kept under a low positive pressure at all times during transportation.

Sufficient quantities of oil shall be supplied in drums with an additional 10% allowed provided. The oil shall have a dielectric strength, when shipped, of at least 30 kV, as measured in accordance with IEC 60296. Test reports, stating the dielectric strength of the oil, shall be submitted to the Engineer prior to filling of the transformer on site.

6.26 Topping Up with Oil and Drying out on Site

If oil is to be added to a transformer or reactor at Site prior to commissioning, the oil in the transformer or reactor shall first be tested for dielectric strength and water content and each container of make up oil shall be similarly tested. The Resident Engineer or his representative shall witness all tests.

Should it be found necessary to resort to oil treatment before a transformer or reactor is commissioned, the Contractor shall submit to the Engineer, in writing, a full description of the process to be adopted, the equipment to be used and a statement of the precautions being taken to prevent fire or explosion.

Should a transformer or reactor arrive on Site without positive pressure of gas in the tank, it shall be dried out on Site at the Contractor's expense.

Clear instructions, in English shall be included in the Maintenance Instructions regarding any special precautionary measures, which must be taken before vacuum treatment can be carried out. Any special equipment necessary to enable the transformer or reactor to withstand vacuum treatment shall be provided with each transformer or reactor. The maximum vacuum which the complete transformer


or reactor, filled with oil can safely withstand without any special precautionary measures being taken shall be stated in the Maintenance Instructions.

6.27 Oil Handling and Test Equipment

An oil processing plant is to be provided to remove solid matter, dissolved gases and moisture from the oil.

The oil treatment plant should be able to achieve a standard of oil purity similar to that specified by the transformer manufacturer for the first filling, and the rate of flow shall be suitable for filling the transformers in this specification but have a minimum value of 9000 litres/hour.

The flow rate shall be variable, but when adjusted it should be steady, continuous and automatic in operation. The degasifier and the filter shall be able to operate together or independently.

The pumps shall be rated suitably for the treatment of the required quantities of oil at ground level, and to deliver oil into the highest part of the oil system of the transformers specified herein.

The plant should be complete with vacuum pump, air cleaning set, cooling unit, suitable rubber hoses for use with oil and all other necessary accessories.

6.28 Transformer Marshalling Kiosk

A weatherproof and dustproof control housing of adequate size shall be located on the transformer near the base. It shall be mounted not less than 610 mm (2 feet) above the base and the space beneath it shall be free from obstruction, which could interfere with outgoing cable or conduit connections. It shall be equipped with the following: -

(a) Earth bus for individually earthing each set of current transformer leads and other circuits requiring earth points. The bus shall include one bolted type connectors of 10 mm 2 stranded copper cable size for each earthed circuit.

(b) Terminal blocks for the termination of all current transformer secondary leads, alarm, control, relay and thermocouple leads.

Terminal block for current transformer and thermocouple leads shall be through type with two clamping screws for each lead or designed for lapped joints with two clamping screws exerting pressure on each connection. Terminal blocks shall accommodate all sizes up to, and including, 16 mm 2 stranded conductor. All current transformer leads shall be kept separate from control leads.

(c) Two weatherproof convenience outlets outside the control cabinet as per latest B.S. 546 for single-phase, 220 volt, 20-ampere service.

(d) A suitable pocket or holder inside the control cabinet for one copy of the instruction manual.


(e) A plain, removable plate located in the bottom of the box of adequate size for terminating all conduits leaving the transformer. (The plate will be drilled in the field)

(f) Contactors for fan motors.

(g) Contactors for oil pump motors (if applicable).

(h) Necessary glands for power and control cables.

(i) Thermostatically controlled, anti-condensation heater for 220 volt, single-phase system.

6.29 400 kV Reactors

Where required by system conditions 400 kV reactors will be connected directly to the outgoing overhead line circuits to compensate for their capacitive charging power.

The reactors shall be three phase, 50 Hz outdoor type either in a single tank or a three-phase bank of single phase units. The reactor shall either be solidly earthed at the neutral or shall have its insulation graded for operation with the neutral earthed through a compensating reactor.


The basis of the cooling system is ONAN, but alternative systems can be proposed by the Contractor for approval by the Engineer.

Dependent on the site conditions the reactor can either be GIS connected or AIS connected and the reactor bushings will be designed accordingly.

The following transformer technical sections apply to the design of the 400 kV reactors.

6.8 - Magnetic circuits 6.9 - Windings 6.10 - Internal earthing arrangements 6.11 - Tanks 6.12 - Bushings 6.13 - Conservators, oil level gauges and breathers 6.14 - Valves 6.15 - Cooling plant

6.20 - Temperature indicating devices and alarms


7. 11 KV TERTIARY COMPENSATING EQUIPMENT SWITCHGEAR AND CONNECTIONS


The work to be done under this Section consists of the design, manufacture, testing supply delivery to site, installation, commissioning and guarantee of the following equipment:

- 11 kV switchgear for the station and earthing transformers and compensation equipment

- Interconnection buswork cables and protection

- Station service transformers

- Earthing transformers.

- Capacitors

- Shunt reactors

7.2 General

The general layout for the 11 kV switchgear and associated compensation equipment connected to the transformer tertiary winding is shown on the single line diagram. The scope shall include interconnections between main single-phase auto-transformer tertiary windings and connections between the tertiary windings and all other 11 kV equipment including all busbars, insulators, supports, clamps, and fittings necessary for the 11 kV system.

The complete switchgear shall comprise a floor mounted, single busbar, metal-clad switchboard suitable for indoor use and shall be constructed in accordance with IEC 62271-200.

7.3 11 kV Switchgear

The switchgear shall be of the metalclad type suitable for indoor installation as shown on the attached single line diagram and shall consist of a single insulated busbar in air insulated busbar chamber metalclad, floor mounted, unit, incorporating enclosures for the circuit breaker units, busbars, and current transformers and auxiliary wiring. Relay panels, potential transformers control switches, alarm lamps and indicating instruments, DAS points connected to a separate terminal kiosk shall be provided with the switchboard.

All switchgear shall be provided with a mimic diagram of black colour for 11 kV system connections.

It shall provide a maximum degree of safety for the operators and others in the vicinity of the switchgear under all normal operating conditions, under all short circuit and internal arcing fault conditions. The interlocks provided shall prevent any maloperation. The switchgear shall be suitable for satisfactory continuous operation.


7.3.1 Degree of Protection The Degree of protection of persons against hazards, on approach to live part, shall be IEC 60529:

- For covers IP33 - For busbar, cable and breaker IP41 - For instruments IP50

7.3.2 Current Ratings Every current carrying part of the equipment including circuit breakers, current transformers, isolating devices, busbars, connection and joints shall be capable of carrying its rated current continuously and in no part shall the permissible temperature rise be exceeded.

In addition all parts of the switchgear, including current transformers, shall be capable of with standing without thermal or mechanical damage, the instantaneous peak and short time currents corresponding to the rated symmetrical breaking capacity of the circuit breakers.

All current ratings specified are the minimum continuous values required under the service conditions specified.

The circuit breaker ratings shall be as specified.

7.3.3 Busbars and Connection The busbars shall be of single copper busbar type, rated continuously as specified. The busbars and connections shall be suitably insulated.

All busbars, connections and earthing-conductors on the switchgear panel shall be of hard drawn, high conductivity copper with constant cross sectional area throughout the length. The busbars shall have heat shrink flexible insulation sleeves. They shall be supported and secured by cast resin insulated connectors capable of withstanding stresses associated with 3 sec short time current.

The busbars shall be arranged so that they may be extended without undue disturbance to the adjacent busbar chambers. The busbars shall be arranged in a separate compartment and high-strength insulation barriers shall be provided at each junction between the adjacent cubicles.

The configuration of the switchgear shall be such that the busbars are brought out to fixed contacts in the upper position within the circuit breaker compartment. The circuit connections shall be brought out to fixed contacts in the lower position within the circuit breaker compartment.

Access to the busbars and connections shall be restricted by means of removal of bolted covers. Covers shall be clearly marked BUSBARS.

All branch busbars to the cable box chambers shall be protected with insulation sheets between the phases and earth.

The 11 kV busbar rating shall be as specified in the Schedules.


7.3.4 Circuit Breakers All circuit breakers shall comply and be fully type tested to IEC 62271-200, IEC 62271-100, IEC 60694 and IEC 62771-110, in independent testing laboratories not associated with the manufacturers or witnessed by an independent observer.

The circuit breaker shall be three-pole, equipped with single trip coils and be trip free and fitted with anti-pumping device.

The circuit breakers shall be suitable for satisfactory continuous operation at the specified rating, at the maximum site ambient temperature. Satisfactory test evidence shall be submitted to confirm the performance of the equipment at all site conditions.

When switching inductive and capacitive currents, the overvoltages produced on any switching duty shall be less than 2.5 p.u. Where the switching over-voltages exceed 2.5 p.u. the manufacturer shall provide appropriate Metal-Oxide surge arresters on both cable and busbar sides of the circuit breaker, on each circuit to protect the system at no extra cost to the purchaser. These surge arresters should be mounted inside the panel.

Circuit breakers having identical characteristics shall be interchangeable. The equipment shall be suitable for operation within its rated duty for maximum operating time with minimum maintenance.

The circuit breaker shall be mounted on withdrawable trucks, complete with high integrity operating and isolating mechanisms, primary and secondary disconnecting devices, auxiliary contacts, manual tripping facilities, operations counter, mechanical position indicator, control wiring, auxiliary relays and contactors as required.

7.3.5 Operating Mechanism The operating mechanism shall be of the motor wound spring stored-energy type unless otherwise approved.

The circuit breakers shall preferably be fitted with motor-charged type power-spring mechanism, suitable for at least 10,000 satisfactory mechanical operations in accordance with IEC 62271-100. It shall be fitted with a mechanical position indicator showing the “Open” and “Closed” positions and with local manual operated features for tripping, closing and spring charging. The operating mechanism shall include an anti-pumping device and incorporate manual trip facility fitted with a guard to preclude inadvertent operation. It shall be possible to manually discharge the springs and to charge the springs with the circuit breaker in either the ‘open’ or the ‘closed’ position.

The circuit breaker shall incorporate a manual trip facility (preferably push button, located on the door of the panel and fitted with a guard or shroud to preclude inadvertent operation) and be capable of being manually tripped from outside if the control power fails (i.e. should trip without DC supply). The charging time for spring charged mechanisms shall not be longer than 25 seconds, and the spring shall be automatically re-charged immediately the switching device has been closed. Facilities for manual charging of the springs shall also be provided. A means shall be provided to uncouple the spring charging motor, at the end of the spring charging process, in the event of limit switch failure. The uncoupling arrangement shall be monitored and operation shall initiate an alarm.


The circuit breaker shall be suitable for remote control of both closing and opening functions. The tripping, closing and auxiliary functions shall be capable of operating at control voltages between 85 per cent and 110 per cent of the rated values. The closing mechanism shall be of “trip free” type. A direct mechanical trip facility and mechanical position indicator shall be provided to show whether the circuit breaker is open or closed. An indicator shall be provided to show the state of charge of the spring, which shall indicate `spring charged' or `spring free'. All controls and indications shall be accessible with the cubicle door closed.

All mechanical position indicators shall be directly driven by their initiating devices. Where electrical power is required for the operation of the circuit breaker e.g. spring charging motor, solenoid operation etc., a 110-volt dc supply shall be utilized.

7.3.6 Draw-out Mechanisms of Withdrawable Circuit Breakers Withdrawable circuit breakers shall incorporate horizontal disconnection facilities and be horizontally withdrawable.

Integral facilities shall be provided for the positioning of the circuit breaker in the "Service", "Test" and "Isolated-earthed" positions. Provision shall be made for rigidly locating the circuit breaker in each position. All necessary interlocking and other features required for safe operation shall be provided. Attempted movement shall not cause a circuit breaker to trip. It shall be possible to test the operation of the circuit breaker in the test position with the control and auxiliary circuits still connected to the circuits contained in the fixed portion of the panel.

Facilities shall be provided for remote indication when the circuit breaker is in its isolated state, i.e. not available for service.

In the test position, a safe working distance shall separate the fixed and withdrawable primary disconnecting busbar contacts, and safety shutters used to cover the live contact access. When the circuit breaker is removed completely from the switchboard panel, all live HV connections, contacts and busbars in the panel shall be automatically covered by lockable safety earthed-shutters.

Secondary control and interlocking electrical connections shall be made by means of self-aligning plugs and sockets. A mechanical interlock shall prevent the circuit breaker from being withdrawn from or inserted into the normal service position when the circuit breaker is `closed'.

Padlocking facilities shall be provided to allow the circuit breaker to be locked in the test or withdrawn position. If a stored energy spring operating mechanism is used for the circuit breaker, then it shall be possible to safely discharge the spring in the test or withdrawn position during maintenance.

When the mass of the circuit breaker and its truck together with all other equipment mounted thereon is greater than 100 kg and isolation of the circuit breaker is achieved by horizontal movement, e.g. truck mounted circuit breaker with horizontally disposed bushings, a mechanical means shall be provided for driving the circuit breaker through the isolating contact engagement and in addition a distance sufficient to obtain the withstand dielectric requirements between the associated contacts.

The mechanical drive shall be interlocked to allow its use only with the circuit breaker in the open position. Plug connections, including those for auxiliary wiring, shall be of the self-aligning type. The fixed portion of plug connections shall be readily accessible for maintenance.


7.3.7 Interchangeability and Isolation of Circuit Breaker Circuit breakers of the same type and current rating shall be interchangeable electrically and mechanically. The circuit breakers shall incorporate horizontal disconnection facilities and be mounted on horizontal withdrawable trucks. Circuit Breaker Isolating Contacts.

7.3.8 Circuit Breaker Isolating Contacts Each circuit breaker shall be connected to the busbars and feeder circuit through plug and socket type isolating contacts, which shall be of the, off load type but shall be suitable for operation whilst the busbars or feeder circuits are energised.

7.3.9 Auxiliary Contacts Each circuit breaker shall be provided with all auxiliary contacts required for control, protection and indication required by this Specification and at least six normally open and six normally closed auxiliary contacts shall be provided as spare. All auxiliary contacts shall be wired to terminal blocks in a multicore cable box for auxiliary cables. Auxiliary relays shall be provided where insufficient auxiliary contacts are available.

7.3.10 Service Life The switchgear shall be designed for a service life of at least 30 years in the environment and for the duty specified on the Data Sheets.

The switchgear should have at least 3 years of service experience and be suitable for a minimum period of 3 years normal continuous operation without maintenance at the duty specified on the Data Sheets.

7.3.11 Fused Disconnect Switches Where Station service transformers are connected to the 11 kV system by fused disconnect switches. The switch shall be designed to provide automatic opening of all poles if all or any of the fuses blow. The switches shall comply with the general requirements of this Specification.

7.3.12 11 kV Protection, Control, Indication and Alarms All protection, control, indication and alarm facilities shall be grouped on a per circuit basis. The equipment shall be installed in a separate compartment. All protection equipment and relays shall be installed in such a way so that they are not affected by vibration due to the operation of the circuit breaker. All protection and control wiring shall be installed within plastic trunking.

Visible terminals of the protection and control wiring and equipment shall be covered by protective insulating covers.

Wiring connecting to apparatus mounted on doors or between points subject to relative movement shall be installed in inflexible corrugated pipes and supported in insulating cleats.


All power operated equipment shall be operable either locally on site or remotely from the Regional Despatching Centre, but the two systems shall not be in operation simultaneously. A facility for selection of “remote” or “local” control shall be provided on site adjacent to the equipment being controlled.

Each cubicle shall be fully wired and equipped with all necessary equipment including alarms, indication, and test facilities, isolating facilities, instruments, fuses and cable terminations etc.

All circuits, equipment, control switches etc shall be clearly labelled as to their purpose and function.

Visual indicating devices shall be provided adjacent to the circuit breaker control handle or switch to show whether the circuit breaker is open or closed. To conserve power and reduce maintenance light emitting diodes (LED’s) are preferred.

The following status and alarm indicators shall be provided with the associated colours:

Red - Circuit breaker ON Green - Circuit breaker OFF Amber - Alarm condition White - Earth switch engaged Clear - Trip circuit healthy Blue - Protective device actuated

In addition, voltage indication shall also be provided. Indication shall also be provided to indicate an earth fault on either side of the bus section circuit breaker.

Indicating lamps (or LED’s) and holders shall be so arranged that replacements and cleaning can be readily effected.

Relays for 11 kV and 0.4 kV switchgear shall be mounted on instrument panels forming part of the switchgear equipment and these instrument panels shall have anti-vibration mountings.

Panel instruments mounted on the 11 kV switchgear shall be provided for Amps on all circuits, and in addition voltage for transformer circuits and busbar sections. All indicating instruments shall be of the flush mounting type, be designed for tropical climate, have dust proof cases, must be capable of carrying continuously the full load current and must not be damaged by fault current.

7.3.13 Interlocks Interlock arrangements shall be as stated in Section 5.11 of IEC 62271-200. Mandatory interlocks shall be mechanical. Electrical or electro-mechanical interlocking shall only be used where specifically permitted by the specification.

All interlocks provided throughout the switchboard shall be of the preventive rather than corrective type, i.e., an attempt to disconnect a closed circuit breaker shall not result in tripping of the circuit breaker.

Interlocks shall prevent any unsafe operation of the switchgear and shall ensure that the operator follows safe and logical sequences of switching device operations.


The interlocking shall support the following principles: -

• To maximise personal safety all switching operations shall be carried out with the switchgear cubicle door closed.

• Isolation facilities shall be considered not to have load making or breaking capacity.

• It shall not be possible to close any earthing switch or earth equipment by circuit breaker transfer unless the equipment to be earthed has been isolated from all local sources of supply.

• It shall not be possible to operate the circuit -earthing device if the busbar circuit breaker/disconnector is in the normal service position.

• It shall not be possible to operate the busbar-earthing device if any of the busbar circuit breakers/disconnectors associated with the busbar to be earthed is in the normal service position.

The following interlocks shall be provided:

(a) The withdrawal or engagement of the withdrawable circuit breaker shall be impossible unless it is in the open position. The operation of the circuit breaker shall be impossible unless it is in the service, disconnected, removed test or earthing position.

(b) Withdrawal of the auxiliary circuit control plug shall not be possible with a circuit breaker in the service/ON position.

(c) It shall be impossible to close a circuit breaker (in the service position for withdrawable types) unless it is connected to the auxiliary circuit, except if it is designed to open automatically without the use of an auxiliary circuit.

(d) Any compartments containing disconnectors shall be interlocked such that the disconnector must be open and the incoming side disconnected/earthed before the compartment cover/door can be opened.

(e) The cubicle door shall be interlocked with the circuit breaker to prevent opening of the door with the circuit breaker in the service/ON position.

(f) Earth switches shall be interlocked with their associated circuit breaker so that they cannot be closed unless the circuit breaker is open (or disconnected for withdrawable types). It shall be impossible to close a circuit breaker unless its associated earth switch is in the open position.

(g) It shall not be possible to operate busbar earthing switches unless all circuit breakers/disconnectors associated with the busbar are in the open position (test position for withdrawable types) and all circuit breaker secondary circuits are connected. Electrical interlocking is acceptable.

(h) A withdrawable circuit breaker shall be mechanically prevented from being inserted into the service position when the busbar earth switch of the associated busbar is closed.


Within withdrawable switchgear, it shall be possible to operate, independently, each set of shutters such that either can be padlocked in the closed position whilst the other is open for earthing and maintenance purposes.

The guarding and screen work of all equipment shall be interlocked with the circuit breaker and the isolating devices in such manner that it cannot be opened unless the circuit breaker and isolating devices are opened and all equipment within the guarded area is de-energised and safe. Unless otherwise approved it shall not be possible to make the apparatus alive while the guarding/screen work is open.

Where key interlocking is employed, tripping of a circuit breaker shall not occur if any attempt is made to remove a trapped key from the mechanism. Any local emergency tripping device and any key interlock device provided for earthing purposes shall be kept separate and distinct from the key interlocking.

7.4 Earthing

In addition to ensuring adequate electrical continuity between all metal non-current carrying parts of the switchboard and the main earthing busbar, particular care shall be taken to ensure that:

(a) Housing of 11 kV switching devices shall be positively earthed (in the service and test positions for withdrawable types) by appropriate earthing connections.

(b) External or exposed parts, e.g. bolts, screening, terminals, insulators, bus ducting and cable boxes shall be bonded to the steelwork frame of the switchboard.

(c) All earthing connections of voltage and current transformers shall be made directly from the terminal blocks to the main earthing busbar.

(d) All metallic instrument cases, protective relay cases, switches etc., shall be properly earthed to the switchboard steelwork frame.

(e) All hinged doors upon which instruments, switches etc., are mounted shall be bonded to the fixed portion of the switchboard panel by a suitably sized flexible braid. Safety doors and barriers shall be similarly bonded.

(f) Means shall be provided for ensuring that the earthing connections to the main earthing busbar of each withdrawable switching device and voltage transformer are made, before the primary connections are made as the device is inserted, and after the primary connections are separated as the device is withdrawn.

7.4.1 Main Earthing Each circuit shall be provided with the facility to earth the cable feeder by means of a device having a making capacity and short-time rating equal to that of the circuit breaker. This shall be achieved by means of an earth switch installed within the switchboard and located between the circuit breaker and cable box. The earth switch shall preferably be designed such that there is a minimum 3 sec delay in changing its direction of operation.


Busbar earthing shall be achieved preferably in a similar manner to that described above by means of an earth switch installed within the switchboard or by means of integral earthing via the circuit breaker for earthing purposes. Where this is impracticable, consideration will be given to the use of portable earthing devices attached via the circuit breaker plug orifice, in conjunction with a voltage checking device.

7.4.2 Temporary Earthing In addition to the main provision for earthing, the design of the switchgear shall be such that a temporary earth can be applied to each equipment for the purpose of permitting work on the unit (e.g. for cleaning of feeder spouts, or to release a circuit breaker for maintenance) after earthing the circuit through the circuit breaker in the prescribed manner and then, in the case of withdrawable equipment, withdrawing the moving portion of the unit. Such temporary earths shall be capable of being applied to each of the phases separately.

Each set of temporary earthing devices shall, where appropriate, be supplied with a suitable box or container together with a set of instructions for the fitting and operation of the equipment.

7.5 Cable Terminations

The switchgear panel shall be provided with appropriate facilities for the independent termination of the 11 kV main cables and the LV, control and auxiliary cables.

Cable connections to the switchgear shall be arranged to accommodate the 11 kV cables, which will rise to the switchgear from a cable trench along the length of the switchgear at the rear.

The 11 kV cable compartments shall be provided incorporating fixed portion of separable connectors (inner cone plug system to EN50181) to allow the termination of single core, copper, XLPE cables rated to suit the duty. The number and type of connector used shall be provided to match the switchgear rating and cabling requirements of the project. The cable sizes are subject to calculation as specified in the Cable Section of this specification. Facilities shall be provided to permit the high voltage testing of the cables from the switchgear end of the circuit.

7.6 Voltage Transformers

Inductive voltage transformers shall comply with IEC 60044-2. The ratings preferred by IEC 60044-2 shall be selected such that the VTs are not loaded to more than 90% of their rated output. The VTs shall be connected to the cable side of the circuits for indication of the presence of voltage.

7.6.1 Type, Ratio, Accuracy Class and Rating The 3 phase voltage transformers shall be of the encapsulated, withdrawable, 3 limb-type, and have star-connected primary and two secondary windings. A secondary star winding shall be used for metering the second winding is spare.


The voltage transformers shall have a voltage factor of 1.2 continuous and 1.9 for 30 seconds. The high voltage windings shall be so designed that saturation of the cores does not occur when 1.73 times normal voltage is applied to each winding. The accuracy class shall be 1.0. The rating of each voltage transformer shall be adequate to match the required load, including the burdens of the remote control and indication circuits with an additional 20%. Each voltage transformer shall carry a nameplate showing serial number, class, type, ratio and output. Each type of secondary circuit shall have segregated fuses or circuit breaker protection in addition to the main secondary protection device.

7.6.2 Connections and Protection The primary star point of the 3-phase voltage transformer shall be insulated. They shall preferably be double wound and have an earthed metal screen between the windings. 11 kV voltage transformer primaries shall be protected by removable high breaking capacity HRC fuses. One pole of secondary windings shall be earthed.

Phases shall be indicated by the colours red, yellow and blue; the terminals shall be marked with the letters R, Y and B respectively.

The phases of the secondary windings shall be connected to the secondary wiring preferably through ganged three-phase 4 pole miniature circuit breakers of the air break type. The secondary star point of a voltage transformer shall be earthed at one point only and local to the transformer. A link shall be provided in the earth circuit and shall be situated at the transformer. The secondary winding terminals shall be connected by bus wiring to suitable local terminal blocks.

It shall not be possible to parallel the secondary windings of any two voltage transformers. The primary fuses shall be placed so as not to be accessible to unauthorised persons.

Isolation of the voltage transformer shall be carried out by a purpose designed disconnector or by withdrawing the entire voltage transformer assembly, e.g. by using guide rails or racking devices from fixed connections designed for the purpose. The VT connections shall be completely shrouded and a cover or shutter shall be provided on the fixed HV part of the panel to cover the HV conductors when the voltage transformer is withdrawn. The operation and locking facilities for the cover or shutters shall be designed to prevent access to the VT fixed terminals.

If miniature circuit breakers (MCB) are used to protect the secondary windings then they shall be equipped with two sets of normally open and two sets of normally closed auxiliary switches which shall be wired to local terminal blocks and an alarm shall be given to indicate that the MCB has been tripped.


Current transformers shall comply with IEC 60044-1 and shall be capable of withstanding without damage the peak and rated one-second short time currents of their associated circuit breakers. They shall be accessible safely without de-energising the busbars and their secondaries shall be earthed at one point through a removable link.


Current transformers for differential protection shall be of the same make and type as those at the remote end of the circuit.

Magnetization curves and D.C. resistance values shall be submitted for each current transformer used for protective purposes.

7.7.1 Type, Ratio, Accuracy Class and Rating All current transformers shall be resin-insulated and inter winding insulation shall withstand electrical stresses and the environmental conditions described in this Specification.

Current transformers for metering shall be of class 1.0 accuracy.

For differential protection the rated secondary current for CTs shall be 1 ampere and be of Class 5P20 accuracy. Current transformers for overcurrent and instrument purposes shall be of accuracy Class 5P10 as specified by IEC 60044-1 and means shall be provided to ensure that the connected instruments are not damaged at the maximum fault currents.

Magnetisation curves and DC resistance values shall be submitted for each current transformer used for protective and metering purposes.

Each current transformer secondary winding circuit shall be earthed at only one point.

Where adequate earth screens are fitted between the primary and secondary windings earthing of the secondary winding shall be via a link mounted in the related protection or instrument cubicle. Where such earth screens are not fitted a separate earth system may be necessary. Wherever possible the connection to earth shall be on the side of the S2 terminals.

When multi-ratio transformer windings are specified, multi-ratio primary windings will only be considered where the protection arrangement makes these suitable for all aspects of the installation. A label shall be provided at the terminals of all multi-ratio windings of the current transformer indicating the connections for each ratio. The connections and ratio shall be indicated for each winding on all connection diagrams.

All current transformers shall have adequate VA ratings and thermal ratings to match the circuits and burdens placed upon them with an additional 20% output. Current transformers used for metering, instrumentation and control shall have the maximum standard rating so as to allow additional external circuits to be connected.

7.7.2 Terminals and Connections The secondary leads from each current transformer shall be connected to terminal blocks mounted on or close to the current transformer. Leads from current transformers used for remote metering shall be wired to a multicore cable box for auxiliary cables.

All terminals and wiring shall be clearly and precisely identified as specified in IEC 60185.


All CT secondary lead terminals shall be connected by means of separate, insulated wires to a terminal block mounted in a conveniently accessible position and be accessible safely without de-energising the bus bars. This terminal block shall be equipped with test and short-circuiting links (or plugs) and terminal screws arranged to facilitate the connection of test equipment. One end of each secondary winding or circuit shall be earthed at this terminal block.

7.8 Station Service Transformers

Each transformer shall be delta/star, with neutral earthed, supplied with on-load tap-changer on the HV winding (+ 10 percent taps). Windings and internal wiring must be copper. Aluminium is not acceptable.

Each transformer shall be rated to supply the total station auxiliary load plus an allowance for the future extension as per general layout and single-line drawing.

(a) Codes, Standards and References

Transformers shall comply with appropriate IEC or B.S. standards or Codes of Practice.

(b) Rating and Type

Transformers shall either be of outdoor type, oil-immersed, self-cooled or dry encapsulated design. Ratings shall be based on an average winding temperature rise, as measured by the resistance method of 55o C with the cooling air maximum temperature 50o C. Where applicable the top oil temperature shall be 50oC. The oil filled transformers shall have overload capabilities in accordance with the latest issue of IEC publication 60354.

Automatic on-load tap-changer is to be supplied with facilities for future remote control. Rating of transformers to be approved by the Engineer.

(c) Accessories

Where applicable, the following additional accessories shall be provided.

(i) Filter connections:

(ii) a 5 cm oil drain valve:

(iii) Handhole in cover to permit access to interior.

(iv) Oil level gauge, magnetic type with low level alarm contacts and wired to terminal box:

(v) Dial-type oil temperature indicators, one for the transformer and one for the tap-changer, each with two sets of alarm contacts plus maximum temperature indication:

(vi) Pressure relief vent:


(vii) Engraved metal nameplate and connection diagram to indicate capacity, type, phase, tap voltage with related currents, frequency temperature rise, weights or core, coils, oil and complete unit, quantity of oil, manufacturer, serial number and date of manufacture.

(viii) Earthing terminal pads:

(ix) Combined pressure and vacuum gauge, if applicable.

7.9 Earthing Transformers

When specified each earthing transformer shall be of the oil immersed ONAN type suitable for outdoor installation and shall have an interconnected star winding which will be connected via cables to a circuit breaker connected to the busbars to be earthed.

The neutral point of the interconnected star winding of each earthing transformer shall be brought out of the tank through a bushing insulator similar to those on the phase terminals. This point may be isolated or may be connected to earth either directly or through an impedance (should that be necessary) in order to provide an earthing point for the neutral of the lower voltage system.

Rating shall be such that for any single-line-to-earth fault the reactance of the earthing unit Xo shall be such that the ratio Xo/X1, as viewed from the fault, will exceed three but be less than the value required for resonant earthing. The short time rating, based on the maximum value of current, which the earthing unit may be required to carry, shall be 30 seconds. Continuous current rating of the earthing unit must be stated in tender. Preference is given for realisation without separate earthing resistor.

Earthing transformers shall be capable of withstanding for a period of 3 seconds the application of normal three-phase line voltage to the line terminal and the neutral terminal connected solidly to earth.

The interconnected star winding of each earthing transformer, when at its maximum temperature due to continuous full load on the auxiliary winding, shall be designed to carry for thirty seconds without injurious heating an earth fault current not less than the value given in the Schedules.

Earthing transformers shall comply with the provisions of this Specification relating to the main transformers wherever these are applicable and shall be provided with the following fittings: -

(a) One thermometer pocket with captive cap.

(b) Dehumidifying breather.

(c) Filter valve and combined filter and drain valve.

(d) A sampling device at the bottom of the tank.

(e) Conservator vessel with removable end cover and prismatic oil gauge.

(f) Double float gas oil actuated relay.

(g) Pressure Relief Device


Shall generally conform with this Specification but with interconnected star "zigzag" winding, with the primary star point earthed through an impedance.

7.10 Capacitors and Series Reactor

7.10.1 General Where specified, capacitors together with a series-tuning reactor shall be provided for power factor correction or system compensation equipment as indicated on the single line diagrams. The capacitors shall be connected to the associated LV switchgear, which shall be provided with the associated control, protection, metering and signalling systems.

The capacitor banks, associated reactors, surge arresters shall be installed in an outdoor enclosure.

7.10.2 Capacitors Each capacitor bank shall consist of single-phase capacitor units connected to form an ungrounded double star 3-phase arrangement with an unbalance current transformer provided in the connection between the two neutrals of the double star.

The capacitor units shall be of the plastic film paper type, mounted on insulated racks and comply with the requirements of IEC 60871 with insulation material of Non-PCB type.

Capacitor banks shall be designed to operate outdoors, continuously at the specified terminal voltage in an ambient temperature of 50°C. Sun shielding shall be provided.

Capacitors shall be capable of continuous operation at 130 per cent of fundamental sinusoidal current.

Capacitors shall be suitable for continuous operation at rated reactive power.

A capacitor unbalance current transformer shall be provided in the connection between the two neutrals of the double star.

Each battery shall comprise an assembly of capacitor units; each unit shall comprise an assembly of one or more capacitor elements in a single container with terminals brought out.

The arrangement shall include all necessary protective racks, insulation between racks, insulation to ground, discharge and damping devices and all other necessary equipment. The capacitor bank racks shall provide accommodation for at least 20 per cent more units than required for the specified duty.

7.10.3 Containers The containers shall be of stainless steel or other approved material. If the latter, then to ensure a long life between repainting, the following finish shall be applied. Acceptance of an alternative finish will be contingent upon an equivalent standard being obtained.


(a) Metallised zinc spray to BS 2569, Part I, 1964. (b) Degrease. (c) One coat of pre-treatment primer. (d) One coat of zinc chromate primer. (e) Two coats of phenolic resin based micaceous iron oxide paint. (f) One coat of phenolic based hard glass paint to an overall film thickness of 150 microns.

7.10.4 Fuses Fuses shall be provided internally for protection of individual capacitor elements or groups of elements. The fuses shall not deteriorate when the unit capacitor is subjected to the discharge test specified nor the currents associated with the day-to-day operation of the capacitor bank.

Internal fuses shall be generally in accordance with IEC 60871

Evidence shall be provided to demonstrate that each fuse is capable of breaking the fault current produced by the failure of the capacitor element or groups of elements or complete unit capacitor to which the fuse is applied without hazard from the fuse or the unit capacitor. The Contractor shall also demonstrate or provide evidence to the satisfaction of the Engineer that the contamination of the impregnant is not such as to affect the reliability of the remaining sound elements.

Fuses shall be so constructed that when they operate due to a defective element(s), the blown fuse will withstand indefinitely the voltage imposed across it under working conditions.

Portable test equipment or other suitable means shall be provided to enable defective capacitors to be readily identified.

7.10.5 Overvoltages and Overloads The capacitor bank must withstand all the transient currents and voltages inherent in the application.

Each capacitor bank shall be capable of withstanding without damage, any overvoltages produced by excessive currents including inrush currents and short circuit currents for earth faults for a period of time not less than the maximum operating time of the associated protective equipment.

7.10.6 Discharge and Earthing Devices Each capacitor unit shall be fitted with a discharge device to reduce the residual voltage from the peak value of the rated voltage within 10 minutes after the capacitor is disconnected from the source of supply.

The Contractor shall ensure that it is not possible to switch on capacitor banks until the voltage at the terminals is less than 10 per cent of rated voltage.


Facilities shall be provided for short circuiting and earthing individual capacitor banks before access is allowed.

7.10.7 Duty Under Fault Conditions Unit capacitors and capacitor banks shall be capable of withstanding without damage, or deterioration of fuses, an external short circuit on the terminals of the live unit capacitor or of the live capacitor bank. Due consideration should also be given to the fact that external flashovers may occur as a result of transient overvoltages and that at the instant of the fault the unit capacitor may be charged up to a voltage considerably in excess of the normal peak voltage. The Contractor will be required to demonstrate compliance with these requirements in a manner to be approved by the Engineer.

7.10.8 Rating and Property Plates In addition to the rating plate, a property plate of approved design and wording shall also be provided.

Property plates may, subject to the approval of the Engineer, be provided on each rack rather than on each capacitor unit. A capacitor bank rating plate shall be provided suitably mounted if possible at a height of 1.75 m from ground level and so attached as to be visible from the exterior of the housing or enclosure of the bank. This plate shall include the rating plate data specified in IEC 60871 as relevant to the rating of the assembled capacitor bank.

7.10.9 Racks for Unit Capacitors The racks shall be designed on a modular basis to carry all the required unit capacitors, conductors, insulators and other fittings and the rigid conductors comprising the necessary circuits under the loadings and factors of safety specified below and to give the specified clearances for the connections between the capacitors and associated circuits specified. The racks shall be designed to facilitate inspection and maintenance.

The number of devices specified to facilitate the easy removal and replacement of capacitor units shall be provided. They shall be designed with the minimum number of separate parts each of which shall not weigh more than 12 kilograms. Means shall be provided to ensure that the paintwork of the capacitor containers is not damaged by the use of the removal device.

7.10.10 Assumed Working Loads The assumed working maximum simultaneous loading of the platforms and racks shall be as follows: -

(a) Vertical loading. The dead weights of unit type capacitors, conductors, insulators and other apparatus carried on the racks.

(b) Deflection. The rigidity of the capacitor bank shall be such that the alignment and satisfactory

operation of the whole of the equipment shall not be affected by the loads to which the banks are subjected.


7.10.11 Construction Where members are stamped or marked for erection purposes the marking shall be legible, and where erection marks are stamped on galvanized material they shall be stamped before galvanizing and shall be clearly legible after galvanizing. All members, bolts and nuts and all fittings shall be galvanized except for racks constructed with aluminium.

7.10.12 Access and Interlocks The access doors in the Capacitor Bank enclosures shall be interlocked in a manner such that access cannot be obtained unless the bank is isolated from incoming supplies and the associated earth switch has been closed. Where the capacitor bank is remote from the switchboard feeding it, an isolating switch shall be incorporated in the capacitor bank enclosure. All electrical interlocks shall function so as to interrupt the operating supply. An approved system of interlocks shall be provided which shall cover the emergency hand operation of apparatus that is normally power operated. Failure of supply connections to any electrical interlock shall not produce or permit faulty operation.

Where the specified clearances are not obtainable with an approved arrangement of the equipment, earthed screen enclosures or partitions shall be provided to prevent approach to any live part. The screens and partitions necessary for each equipment shall be included in this Contract.

In addition to the interlocking equipment, provision shall be made for accommodating padlocks, supplied under this Contract, on all access doors, earth switches etc.

7.10.13 Rack Insulation The insulation of the racks of capacitor units and the protection equipment shall comply with the relevant IEC recommendations for a three-phase system highest voltage. All clearances shall be to the approval of the Engineer. The insulation shall be of porcelain except where otherwise approved by the Engineer.

7.10.14 Terminals Suitable high voltage and neutral end terminals for connectors shall be provided on each phase of the capacitor bank.

7.10.15 Series Reactors 7.10.15.1 General Reactors shall be provided in series with each phase of the capacitor banks.

Reactors shall comply with, IEC 60289 and with the requirements of this specification.

The design and manufacture of the reactors shall be such that the noise level is a minimum and that the level of vibration does not adversely affect any clamping or produce excessive stress in any material.


The framework, clamping arrangements and general structure of the reactors shall be capable of withstanding any shocks to which they may be subjected during transport, installation and service. The entire assembly shall be mounted on post insulators of the appropriate insulation value.

The materials utilised in the construction of reactors should be selected to minimise any fire risk.

Each reactor shall be fitted with bolted terminal clamps. Means for lifting reactors shall be provided.

7.10.15.2 Windings Winding insulation and all non-metallic material used in winding stacks shall be so treated that no further shrinkage shall take place after assembly.

Coils shall be constructed to avoid abrasion of the insulation, (on transposed conductors), allowing for the expansion and contraction encountered during normal operation. The insulation on the conductors between turns shall be of paper.

The windings and connections shall be braced to withstand shocks that may occur during transport or due to switching or other transient conditions during service.

Where the yoke supporting channels are adapted for taking up shrinkage in the windings, the arrangement shall be such as to throw a minimum amount of stress on any core bolt insulation.

If the winding is built up of sections or disc coils, separated by spacers, the clamping arrangements shall be such that equal pressure is applied to all columns of spacers. All such spacers shall be securely located and shall be of suitable material.

Windings shall be designed with sufficient electrical clearance in air between adjacent layers of conductors. Where additional insulation is provided on conductors, this insulation shall be capable of withstanding temperatures of the class specified.

7.10.16 Earthing Arrangements. All metal parts other than those forming part of any electrical circuit shall be earthed in an approved manner. To facilitate this, an earth terminal, of adequate size, shall be provided near to the reactor base to which the substation earth system can be connected.

7.10.17 Surge Arresters Surge arresters, or an equivalent method of limiting overvoltages arising from abnormal oscillatory conditions, shall be provided to protect each phase of the capacitor banks.

The surge arresters shall comply with this specification as appropriate and shall be suitable for use with capacitor banks, in particular with respect to switching transient over-voltage and overcurrent and energy absorption capability.


7.11 11 kV (Tertiary) Shunt Reactors

7.11.1 General Where specified, shunt reactor shall be provided for compensation equipment as indicated on the single line diagrams. The reactors shall be connected to the associated LV switchgear, which shall be provided with the associated control, protection, metering and signalling systems.

The reactors shall be three phase, 50 Hz, ONAN rating outdoor type.


The reactor shall be suitable for a cable connection to the 11 kV switchgear.

The following transformer technical sections apply to the design of the reactor.

6.8 - Magnetic circuits 6.9 - Windings 6.10 - Internal earthing arrangements 6.11 - Tanks 6.12 - Bushings 6.13 - Conservators, oil level gauges and breathers 6.14 - Valves 6.15 - Cooling plant


8. CONTROL, INDICATION, METERING AND ANNUNCIATION

8.1 General Requirements

8.1.1 Extent of Supply This performance specification covers the design, supply of equipment, installation and commissioning of control, indication and annunciation equipment for 400/132 kV transformer substations. At new substations a Substation Control System (SCS) shall be provided for each 400/132 kV substation. At existing substations the existing systems shall be augmented or replaced with a new SCS as specified in the Scope of Works or as otherwise indicated by MOE.

The Generic specification “Standard Specification for Telecommunication and SCADA Systems – December 2004” shall be referred to along with the performance requirements for the equipment contained in this specification. Quantities and configuration shall be determined by the specific site survey process, in agreement with the Employer’s Representative.

The SCS shall provide all the facilities for the safe and effective control of the substation plant and equipment as specified. Provision is to be made within the SCS to allow for extension and programming to include two additional 400 kV “diameters” (two feeders and two transformers) and four 132 kV bays. The extension hardware will not be required as part of this contract, but the SCS shall allow the future addition by connecting additional Bay Control Units into the existing LAN, adding to the existing Master Control Unit (if necessary) and modifying the existing site database.

The SCS shall be capable of serving as an RTU to the SCADA system master station located at the National Control Centre (NCC), acquiring and transmitting substation data to the NCC and executing commands sent from the NCC.

The communication equipment required at the substation for the connection between the SCS and the SCADA system at the NCC shall be as specified in the Communication Equipment section of this specification.

The confidence testing of the operation of the substation plant from the NCC SCADA system via the SCS and other control and monitoring from the Substation SCS and the NCC is included in the Works. The equipment shall be entirely compatible with the communications protocol as may be required by the NCC and with the communications media available. The Contractor shall undertake specific testing to demonstrate the compatibility of the SCS with the NCC.

8.1.2 Plant Control Strategy 8.1.2.1 Circuit Breaker Opening Each 400 kV breaker phase shall be equipped with two trip coils. 132 kV and 11 kV breakers shall be equipped with a single trip coil. Each trip coil shall be individually protected. Fuses shall be provided on each appropriate relay panel.


Circuit breaker opening shall be possible from:

(a) The NCC via the SCS system

(b) The substation control point via the SCS system

(c) The Local Control Cubicle – via the Local Control Mimic for normal and emergency operation.

(d) The Local Control Cubicle – via the Local Control Mimic, for maintenance. This is only to be operative when the circuit breaker is under test, with the Test/Normal switch in the Test position.

(e) When any circuit breaker Test/Normal control selector switch is switched from Normal to Test and from Test to Normal to ensure that the circuit breaker is open during and after maintenance.

(f) Protective relays energising the breaker “A” & “B” trip circuits via tripping logic.

8.1.2.2 Circuit Breaker Closing The breaker shall be equipped with one closing coil per phase for 400 kV, 132 kV and 11 kV. The close coils and close circuits shall be protected by the same device which shall be separate from the trip circuits. Fuses shall be provided in the Relay Building on each appropriate relay panel. Breaker tripping shall be possible from:

(a) The NCC via the SCS system.



(d) The Local Control Cubicle – via the Local Control Mimic, for maintenance. This is only to be operative when the circuit breaker is under test, with the Test/Normal switch in the Test position. Additional test facilities may be provided at the circuit breaker itself.

(e) The Auto Reclose Scheme.

8.1.2.3 Circuit Breaker Local/Remote Selection Each circuit breaker shall have a Local/Remote selector switch located in its Local Control Cubicle for 400 kV and 132 kV and in the circuit breaker front panel for 11 kV. The switch is to perform the following functions:

(a) In the Local position, local control functions, including protection, shall be connected, permitting operation of the breaker locally in both close and trip circuits of all poles.

(b) In the Remote position, all remote functions, including protection, are to be connected, permitting operation of the breaker from the SCS in both trip and close circuits of all poles.

(c) A “Local/Remote” indication shall be provided at the LCC and SCS.


8.1.2.4 Circuit Breaker Test/Normal Selection Each circuit breaker shall have a Test/Normal selector switch located in its Local Control Cubicle for 400 kV and 132 kV and in the circuit breaker front panel for 11 kV. The switch is to perform the following functions:

(a) In the Normal position, local or remote control functions, including protection, shall be connected, permitting operation of the breaker either locally or at the SCS in both close and trip circuits of all poles.

(b) In the Test position, all remote functions, including protection, are to be disconnected, permitting operation of the breaker locally in both trip and close circuits of all poles.

(c) A “Test Position” indication shall be provided at the LCC and SCS.

8.1.2.5 Trip Circuit Supervision Each trip circuit shall be continuously monitored, with the breaker in either the closed or the open position. The “A” & “B” trip circuit supervision relays for each 400 kV circuit breaker, shall initiate a common Trip Circuit Fail alarm at the SCS. The single supervision relay of each 132 kV circuit breaker shall have a similar facility.

8.1.2.6 Circuit Breaker Discrepancy Indication If the circuit breaker operates automatically, the SCS shall highlight the changed item of plant. . A feature is to be provided to stop the highlighting, without affecting the annunciation of further changes.

8.1.2.7 Synchronising and Dead Line/Bar Check Interlocks 8.1.2.7.1 General A synchronising scheme shall be provided for all circuits to enable the safe interconnection of two sources of supply only when the phase difference, the rate of change of phase across the connecting circuit breaker and the respective voltages are within certain limits. When necessary, the scheme shall incorporate automatic voltage selection of the appropriate incoming and running voltages using circuit breaker and isolator auxiliary contacts or voltage selection relays. On the 132 kV double busbar, the busbar side of the circuit breaker across which synchronising is to be effected is designated the running supply and the other side, usually the feeder side, is designated the incoming supply.

Large primary system earth fault currents may give rise to undesirable circulating earth fault currents in voltage transformer secondary circuits if these are earthed. Isolating interposing transformers shall therefore be provided for synchronising purposes. Back energisation of voltage transformers on dead primary plant is not permitted and thus, where voltage selection is provided, the scheme shall be fail safe so that component failure cannot result in voltage transformer paralleling.


8.1.2.7.2 Check Synchronising Facilities (a) Equipment

The following equipment, plus any additional auxiliary equipment necessary to ensure correct functioning of the scheme, shall be provided: -

(i) Operation of the scheme shall be dependent upon the actuation of a synchronising selection, in such a way that only one circuit at a time can be selected for synchronising. This shall enable the appropriate incoming and running supplies to be applied to a check synchronising relay. Operation of the synchronising selection also prepares for closure of the circuit breaker via the control switch and a contact of the check synchronising relay.

(ii) A check synchronising relay. Check synchronising relays for manual synchronising provided, shall be utilised for auto-reclose requirements. A guard feature shall be provided to ensure that the check synchronising relay contact is closed before the closing switch is operated to close the circuit breaker. If the closing switch is operated before the check synchronising relay contact closes then circuit breaker closing should be prevented. A facility should also be included to detect welding or permanent closure of the synchronising relay contacts and prevent closing of the circuit breaker.

(iii) Interposing transformers for incoming and running voltage supplies. Phase to neutral voltages shall be used for synchronising purposes and the synchronising equipment shall operate satisfactorily over the range of 80 to 120 per cent of its rated value.

(iv) Voltage selection equipment, either auxiliary contacts from primary equipment or voltage selection relays, where specified.

8.1.2.7.3 DBC/DLC Interlocks Closure of a circuit breaker interconnecting two circuits may be required where the conditions for synchronising cannot be satisfied due to the absence of either running or incoming supply. In these cases, Dead Line Check (DLC), Dead Bar Check (DBC) and `Synchronising Override' interlocks shall be provided.

A DBC interlock permits reclosure only if the busbar is de-energized on all three phases. A DLC interlock permits reclosure if the associated line is de-energized on all three phases. In both cases the opposite supply to that which is de-energized must be energized. A busbar or line is considered to be de-energized when the voltage is less than 20 per cent of rated voltage and considered to be energized when at least 80 per cent of rated voltage.

An interlocked check synchronising override facility per circuit breaker shall be provided to enable the contact of the check synchronising relay in the closing circuit to be by-passed. Operation of this switch shall be interlocked with the voltage interlocks of DBC or DLC above, to prevent override of check synchronising unless one or both voltage supplies are absent.


8.1.2.7.4 Remote Supervisory Control The synchronising facilities available at the substation shall be repeated for the NCC, via the SCS.

8.1.2.7.5 Check Synchronising Relay Check synchronising relays shall measure the following parameters of incoming and running voltages:

(a) Phase angle difference. Adjustment of the phase angle between incoming and running voltages over which the relay contacts will close shall be provided over the range 20°to 45°. (Note - this results in a total angular segment over which circuit breaker closure is permitted of 40° minimum to 90° maximum).

(b) Rate of change of phase (slip). The maximum slip frequency at which closure is permitted is a function of circuit breaker closure time and adjustment shall be provided for this. The method of measurement of slip in which it is ensured that the true phase angle difference does not exceed the set phase angle difference for more than a given time, is preferred. A time range of 2 to 10 seconds is required. Alternative methods, e.g. direct instantaneous measurement of true slip frequency, are permitted and a range of settings of 0 to 0.125 Hz/sec is required. If the preferred measurement method is not used, a timer shall be provided so that at least 2 seconds must elapse between application of both ac supplies to the check synchronising relay and an output being given.

(c) Voltage difference. A voltage check feature shall be incorporated which shall inhibit operation of the check synchronising relay if either one or both of the synchronising voltages is less than a preset percentage of rated voltage. The voltage check feature shall be adjustable over the range 80 per cent to 90 per cent of the relay rated voltage.

8.1.2.8 Disconnect Switch Control The 400 kV and 132 kV disconnect switches are to be motor operated and controllable from:

(a) The NCC via the SCS system.



(d) The Local Control Cubicle – via the Local Control Mimic, for maintenance. This is only to be operative when the disconnector is under test, with the Test/Normal switch in the Test position. Additional test facilities may be provided at the disconnect switch itself.

(e) Line disconnect switches shall not be operated automatically. Transformer disconnect switches may be opened automatically by the appropriate protection.

Circuit breaker auxiliary switches shall interlock the open and close circuits such that control is inoperative unless the related circuit breakers are open or other conditions allowed in the interlocking scheme are fulfilled.


8.1.2.9 Disconnect Switch Annunciation If the disconnect switch operates automatically, the SCS shall highlight the changed item of plant and operate the workstation audible sounder. A feature is to be provided to stop the highlighting and sounder, without affecting the annunciation of further changes.

A warning shall be provided to check for the three phases of single pole switches being out of step. One common alarm shall be provided separately for the disconnect switches of each feeder and transformer, where relevant

8.1.2.10 Earth Switches All earth switches shall have their status indications available at the SCS and NCC.

8.1.2.11 Transformer Tap Changer Control The 400/132/11 kV transformers shall have on load tap changers controlled by an Automatic Voltage Control facility (AVC), in line with the requirements of section 6.17 On-load Tap Changing Equipment, of this Specification.

The “R” phase phase-earth voltage signal from the transformer 132 kV VT shall be provided for the Automatic Voltage Control scheme. A current signal for line drop compensation shall be provided from the transformer.

8.2 Station Metering

In addition to the facilities provided from the SCS workstation, the following station metering facilities shall be provided:

8.2.1 System Voltage Local Indication (400 kV) A large indicating voltmeter shall be provided for the 400 kV system voltage indication. The phase-earth voltage shall be obtained from each bus wound VT via an automatic changeover relay. The meter shall be calibrated to read phase to phase voltage and shall be mounted adjacent to the control workstation in a prominent location.

8.2.2 System Voltage Local Indication (132 kV) A large indicating voltmeter shall be provided for the 132 kV system voltage indication. The phase to earth voltages shall be from the 132 kV bus voltage transformers via an automatic changeover relay. The meter shall be calibrated to read phase to phase voltage and shall be mounted adjacent to the control workstation in a prominent location.

8.2.3 400 kV System Frequency (Local Indication) Frequency indication for the 400 kV system shall be provided. The frequency signal shall be obtained from the same source as the local 400 kV indicating voltmeter voltage above. The frequency meter shall be an AC type indicating meter, mounted next to the 400 kV system voltmeter, above.


8.2.4 Voltage Recorder (Local Indication) Voltage recorders shall be provided for the 400 kV and 132 kV systems. The voltage signals shall be obtained from the bus VTs, via a manual changeover switch. Phase to earth voltages shall be recorded. The recorders shall be located on the station totalised metering panel.

8.2.5 Station Totalising Metering (Local) Station total metering shall be provided to record the kW, kVAr and kWh actually supplied through the power transformers from the 400 kV to the 132 kV level. Totalised MVAr supplied to the transformer tertiary will also be recorded, where compensating plant is connected.

DC potentiometer recorders shall be utilised.

The inputs to the recorder shall be derived from the same sources as the indicating metering.

Total station kWh readings shall be recorded on a printometer type kWh meter.

8.2.6 Energy Meters The kWh meters shall be shipped to site as loose equipment, suitably packaged. The Contractor shall arrange to have all meters delivered to the MOE Meter Testing Station for calibration and certification.

After certification, the contractor shall collect the meters from the Testing Station and install them at the respective substations.

All costs incurred in calibration of the meters shall be paid by the contractor.

8.2.7 Station Clocks The contractor shall supply a station clock to match the station meters and supplied with an anti-reflection dial, suitable for dc operation from the station battery and be accurate to two seconds per month or better. The dial is to have "English" numerals, a sweep second hand and be mounted adjacent to the control workstation at a location agreed by the Engineer.

A second synchronous wall mounted clock, suitable for operation from 220V, single-phase 50 Hz supply, is to be mounted adjacent to the control workstation at a location agreed by the Engineer.

8.2.8 Metering Transducers Transducers in general shall be provided in accordance with BS EN 60688 and are to have the following characteristics:

Auxiliary power if necessary (A.C. is not accepted)

110 V D.C.

Nominal voltage input 120 Volts

Nominal current input 1 or 5 amps (to suit)

Full scale calibrating watts 200 watts

Output at full scale (d.c.) 0 - 5, -5 / 0 / +5 mA


Output load required 0-2 k ohms (max. 3 k ohm)

Accuracy / Linearity Class 1.68

Power Factor range Unity to lead or lag zero

Temperature range -100C to + 600C

Temperature effects on accuracy ±0.5% per 100C from 300C

Frequency range 45 - 55 Hz

A.C. component (Peak) 1 %

Response time to 99% of final value 200 ms

Voltage range 85 - 125 Volts

Input overload limit potential 150 Volts

Input overload limit current 2A cont. 20A for 1 second

Voltage burden (max. per element) 4 V.A.

Current burden (max. per element) 2 V.A.

Calibration adjustment 0 - 110 % ±10%

Zero adjustment ± 2% at least

Dielectric test-input to output to earth

For input insulation 2 kV. 50Hz, 1 min

impulse 5 kV, 1.2/50 ms

High frequency 2, 5 kV, 1 MHz

For output insulation 2, 5 kV, 1 MHz

8.3 SCS Specification

8.3.1 Introduction A distributed architecture Substation Control System (SCS) shall be provided to enable the substation plant to be monitored and controlled remotely from the substation control room. The SCS shall also be capable of serving as a Remote Terminal Unit (RTU) to the Supervisory Control and Data Acquisition (SCADA) system master station located at the National Control Centre (NCC), acquiring and transmitting substation data to the NCC and executing commands sent from the NCC.

Where the Contractor can provide suitable numeric equipment that he can demonstrate has been implemented in a similar environment to Iraq, the SCS can be combined with the protection system, as an Integrated Protection and Control System. In this case, the following sections of the Specification can be treated as functional requirements that may be delivered in a different way. The Contractor shall provide full details of the previous implementation of the proposed equipment, together with its operational and maintenance history, to allow an informed decision to be made on its suitability for this project.


8.3.2 Design Principles The SCS shall be designed to achieve a high level of availability, reliability and safety in operation. The design shall be ‘fail safe’ such that failure of any component shall result in all functions affected by the failure defaulting to a defined ‘safe’ state. It shall be fault tolerant such that the failure of any single component within the overall system shall not affect the ability of the remaining healthy components in the system to continue to operate normally and for its functionality to remain available.

Essential functionality, i.e. that required for the continued overall operation of the SCS, shall be tolerant to single component failures. This may be achieved, for example, by using dual redundant hot/standby arrangements or by automatically re-distributing the functionality over the remaining operational components so that loss of any one component does not result in the loss of any functionality. The communications links between components within the overall SCS shall be regarded as essential functionality and the SCS must continue to operate with full functionality if any single communications link is out of service.

The system shall continuously monitor its own health and produce alarms for all detected failures. These alarms shall be presented in the alarms lists on the operator workstation and, as far as possible, by lighting ‘fault’ warning LEDs on the affected equipment itself, e.g. on individual circuit cards. There shall be no cases in which undetected failures could occur anywhere within the overall SCS, including within the communications links between the components of the system.

The equipment and the enclosures it is mounted in shall be designed to facilitate ease of maintenance, particularly fault-finding and replacement of components, e.g. replacement of rack mounted circuit cards. As far as possible, and consistent with safe operation, it shall be possible to ‘hot swap’ components such as I/O cards.

The equipment shall be robust, suitable for the operating environment in which it is installed and require minimal maintenance.

Each sub-system within the SCS shall be designed to meet an overall availability of at least 99.98 per cent based on a Mean Time To Repair (MTTR) of 8 hours.

The Contractor shall provide a Functional Design Specification that will allow the Employer to review and approve the facilities being provided in the SCS, and on which the testing documentation can be based.

8.3.3 System Architecture The SCS shall be based on a distributed architecture complying with the relevant IEC Standards. The proposed configuration of the equipment and the availability and security provided by the proposed architecture shall be described fully in the Tender.


The SCS shall typically comprise the following components:

• Master Control Unit (MCU) • Bay Control Units (BCU) • Operator Workstations • Local Area Network (LAN) • Communications Links to Off Site Control Systems

Bay Control Units shall normally be mounted adjacent to the Local Control Cubicle (LCC) of each switchgear bay for 400 kV and 132 kV and on or adjacent to the switchboards for 11 kV. They shall be connected to the control and indication circuits of the Local Control Cubicle to provide the interface between the substation plant and the SCS. The Bay Control Unit shall include facilities for the control, status indication (in mimic diagram format), analogue readings and alarms of the switchgear bay equipment.

The Master Control Unit typically provides overall supervision and management of the entire SCS. It may also provide communications ports supporting various data transfer protocols to enable the substation plant connected to the SCS to be monitored and controlled from remote points, e.g. from operator workstations in the substation control room and from remote SCADA systems at NCC. This communications interface function may also be provided by devices other than a Master Control Unit.

Since the substation is manned, and consistent with the single failure principle, duplicate Operator Workstations shall be provided comprising a graphical user interface for monitoring and control of the substation plant. Either workstation shall have full access to all of the SCS facilities. They shall be located in the substation control room and each shall be fed from an uninterruptible power supply source to ensure continued operation following loss of mains power supply.

A GPS receiver with antenna and cable, for time synchronisation of the SCS internal real-time clock, shall be provided in order to provide accurate time stamping of alarms and recorded events. The GPS shall be equipped to cater for the specified requirements and, in addition, be equipped with three spare ports.

8.3.4 System Functions 8.3.4.1 General The SCS shall provide, but not be limited to, the following functions that are generally intrinsic to SCS and SCADA systems. The Tenderer shall provide details of the full range of facilities provided by their system in their Tender submission.

(a) Display of the substation single line diagram and individual feeder mimic diagrams with status indication.

(b) Indicate in the mimic diagram plant status, voltages, currents, frequency, together with power factor, active and reactive power flows. High/Low limit excursions of measurands shall be alarmed and programmable.


(c) Acquire, display and printout substation events, individual feeder and substation equipment alarms with date and time stamp

(d) Acquire status, with plausibility checks, of the circuit breakers, disconnectors and earthing switches.

(e) Be capable of performing sequential control functions, such as auto-reclosing of breakers, taking feeders in/out of service, load shedding and load curtailment.

(f) Provide switch interlocking such that the operation of primary plant is prevented unless specified conditions are met. Interlocking functionality shall be available at bay and substation level. (The hard-wired interlocking scheme as specified shall also be provided and the SCS scheme shall provide an additional guard facility to ensure safe operation, based on the same logic).

(g) Perform supervised operations (Close/Open) on circuit breakers, busbar and line disconnectors.

(h) Perform check synchronisation functions. (The hard wired check synchronising relays and associated scheme as specified shall also be provided and the SCS scheme shall provide an additional guard facility to prevent closing out of synchronism).

(j) Perform reporting of acquired data in user-defined formats (numerical and graphical logging) including data from tariff metering. This data shall also be suitable for transmission in text format to another device for further data processing.

(k) Read relay settings, measured values and evaluate stored data.

(m) Storage of process data in managed files for future use.

(n) Resetting of electrical trip lockout relays.

(p) Record station external ambient temperature and humidity periodically.

(q) Receive and process commands from the NCC, process and transmit status, measurements and alarms to the NCC. It shall be possible to generate summary data to send to the NCC

(r) Provide access security to both operational and administrative functions, separately, by username and password.

(s) Be self-supervising, display its own system alarms and hardware status.

8.3.4.2 Commands All commands available at the substation in the SCS shall be capable of being operated at the National Control Centre, subject to the agreement of the SCS Overall Facility Schedule.


All command sequences shall be performed using a select then execute routine. The routine shall minimise the likelihood of accidentally performing the execute step as part of the selection step. Furthermore, there shall be a maximum time between the selection step and execution with the command sequence being cancelled if the execution is not performed within that time.

Prior to the execution of any command, the software shall perform a check to validate that the user has the authority to execute the command. Authority violations shall be indicated to the operator via a message on the VDU.

A ‘cancel’ key and/or poke point shall be provided to allow termination of any command sequence before it is executed.

8.3.4.3 Alarm and Indication Handling All alarms and indication changes annunciated in the SCS shall be treated in the same way i.e. as an Event. Each event shall be capable of being repeated to the National Control Centre, subject to the agreement of the SCS Overall Facility Schedule.

Two types of alarms shall be supported, these being fleeting and non-fleeting. The alarm type shall be configurable on a point-by-point basis.

Two types of indication shall be supported, these being single point and double point. Single point indications shall be used where no intermediate state needs to be identified. The indication type shall be configurable on a point-by-point basis.

All events shall be brought to the attention of the operator. The operator shall have the facility to accept events individually or as a page of events at a time. The name of the operator acknowledging an event shall be recorded and displayed in the event list.

When an event occurs, the workstation audible alarm shall sound and the appropriate entries shall be highlighted in the event list. Indications of changes of plant state shall flash the plant symbol on the SCS mimic diagram and alarms shall flash the “Alarm” symbol adjacent to the plant on the mimic.

Silencing events shall not inhibit the annunciation of further events or constitute an acknowledgement of the event.

Facilities shall be provided for the processing and display of events on the operator interface and shall include but not be limited to:

• Grouping on a bay basis.

• Grouping on the basis of type of event such as circuit breaker operation, protection operation, overloads, communication failures, etc.

The event list shall be displayed in chronological order.

Each event entry shall include the time and date of occurrence, location, device or other identifier, action, status, and value and normal status limits.


Navigation facilities shall be provided to enable the user to rapidly call up the display or area of a display on which the plant relating to a specific event selected in an event list appears.

8.3.4.4 Measured Value Lists Measured values comprising circuit loadings (Amps, MW, MVAr), voltages ( kV), counter and integrated values (MWh, MVArh) and frequency (Hz) shall be available for display in the form of lists and tables in addition to being displayed on the single line diagrams. Where required, these shall be derived from transducers. Transducers shall be mounted to avoid long AC cable runs.

8.3.4.5 Supervisory Requirements (NCC) The SCS shall provide for control of the following from the National Control Centre:

Close/open of all circuit breakers. Close/open of all disconnectors. Resetting of all electrically reset trip relays. Control of transformers. Acceptance of all active alarms incoming from a substation.

The facilities actually made available at the NCC for each substation shall be as detailed in the SCS Overall Facility Schedule, and shall be agreed with the Employer’s Representative.

The “Local/Remote” switch, located at the Local Control Cubicle shall allow control from the NCC only when in the “Remote” position. When the switch is selected to “Remote”, a further authority needs to be given from the SCS before control is transferred to the NCC.

The transfer of control from SCS to NCC shall be achieved through software, without affecting the safe operation and control of the substation.

On/off (open/close) and other position indication shall be provided to the NCC for the following items:

Circuit breaker. Disconnectors. AIS line reactor and GIS circuit earth switches and temporary earths. Local or remote control in service. All necessary indications to allow proper operation of the transformer Automatic Voltage Control facility.

These indications shall be transmitted to the SCS/NCC irrespective of the position of the “Local/Remote” selector switch.

Measurement signals shall generally be provided for the NCC as follows:

Feeder and transformer MW, MVAr, kV and A Busbar (phase to phase) voltage Busbar frequency. Feeder and transformer energy (MVAh, MWh and MVArh)


These signals shall be transmitted to the SCS/NCC irrespective of the position of the “Local/Remote” selector switch.

8.3.4.6 Trends The SCS system shall be capable of displaying any analogue value in graphical form to show the trend of the value over a selected time period. The trend display shall have adjustable x and y axis, indicate up to 10 values and operate either using real-time or historical data from the database.

8.3.4.7 Data Logging The SCS system shall incorporate long-term data logging facilities for all analogue, digital and other internally generated signals.

Any analogue or digital value defined on the SCS system shall be available for storage and subsequent re-call.

All signals shall be scanned periodically and updated values or digital status changes stored. Date and time tags shall be allocated to each signal.

Data shall be stored for up to three months on a suitable storage medium for subsequent re-call at a later date. An alarm shall be given to the operator when the storage of data approaches the capacity of the storage medium. All data shall be capable of being archived and retained for future reference.

The operator shall have the facility to recall data held in the data logger memory or from archives over a specified period of time. The information may also be restricted to specific SCS data points. The requested information may be presented on the operator’s workstations either in tabular form or as selected variables on a trend display. Information on print-outs may be either in tabular form or in a preformatted report form and may be produced automatically at specific times or on request.

It shall be possible to compare on the same display, trends, real-time data and historical data from the archives. This shall not affect the operation of the on-line data logging.

One printer shall be designated primarily as the operational “on demand” log. In the event of a printer failure facilities shall be provided, both automatic and manual to enable changeover to another similar printer which shall be provided by the Contractor.

The Operational log shall record and print on demand when required, the following information:

(a) Status changes.

(b) Onset and clearance of all alarms with facilities for distinguishing between the types of alarms, e.g. ‘urgent’, ‘non-urgent’, ‘group’, ‘individual’, etc.

(c) Control operations (both successful and unsuccessful).

(d) Operator actions such as alarm limit changes, tagging, hand-dressing, removal of parameters from scan, inclusion of new parameter into scan, alarm acknowledgement, log on, log off, etc.


This information shall be printed on the designated printer with each item consisting of the data and time of occurrence, together with a description of the operation, event or alarm, and sufficient information to enable full identification of the feeder/item of plant affected.

The operation log shall also be available as a VDU list of sufficient size to allow the display of information covering 5000 alarm/events.

In addition to the logging printers, a colour printer shall be provided to enable screen dumps and graphical displays etc to be printed.

8.3.4.8 Hand Dressing The single line diagram will contain variable elements, some of which are updated automatically by the application and some that are hand-dressed by the operators e.g. plant where remote indications are not available. Hand-dressed data shall be suitably indicated by a symbol or tag. The hand-dressed changes shall be inserted automatically in the database.

It shall be possible from the operator workstation to remove from scan any measurement, alarm or indication that comes within his area of responsibility. This shall be suitably indicated on the display and additionally a symbol or tag shall be used to indicate the removal from scan. It shall then be possible, from the workstation, to insert a new (hand-dressed) value for the element, with the hand-dressing also suitably indicated by a symbol or tag. The hand-dressed changes shall be inserted automatically in the database.

On manual restoration of the elements back into service, the readings shall again be recorded in the database, returned to their normal presentation and hence regularly updated on the displays.

Hand-dressing operations, as described above, shall be suitably tagged for logging purposes.

The system must recognise an attempt by the operator to make an invalid hand-dressing operation and this should be blocked, with a suitable error message being displayed on the screen.

8.3.4.9 Operator Interface The design of the operator interface shall be based on standard software packages and provide a Windows, Icons, Menus and Pointer (WIMP) style of presentation and use interaction with the system. All user actions shall be initiated using the pointer/keyboard and standard ‘windows’ methods.

The system shall provide facilities for the display of the entire substation single line diagram as a single display along with other displays for specific purposes, as required.

Pan, zoom, decluttering and windowing facilities shall be provided to allow the operator to navigate through the displays and adjust the level of displayed detail to that appropriate to the task they are performing.

To ensure the interpretation of information from displays is intuitive and not confusing to the operators all displays and lists shall be constructed following a consistent overall design philosophy. For example, all lists shall display in the same manner with new entries always being added to the top of the list or to the bottom of the list.


The software shall also guide the user, step-by-step, through each sequence by identifying, preferably via a visual technique on the workstation, the remaining valid entries.

Any invalid entry shall be detected by the software, ignored and an explanatory message displayed on the VDU. It shall then be possible to continue the sequence with a valid entry.

The system shall support context sensitive on-line help facilities. The help screens shall be easily customised to suit the owner’s needs.

8.3.4.10 System Operating Points The substation will normally be manned, but also it will be monitored/controlled when selected from the National Control Centre via the SCS. It shall be possible to operate Substation plant in the following ways: -

• Supervisory - from the National Control Centre

• Remotely - from the substation control room

• Local – from the Local Control Cubicle Local Control Mimic

• Maintenance – from the Local Control Cubicle Local Control Mimic, for maintenance purposes only.

The design of the SCS and substation plant shall be such that control of any item of plant is only possible from one control point at any particular time and the transfer of control between these points shall be achieved without affecting the safe operation, monitoring or control of the substation.

8.3.4.11 Modes of Operation As a minimum, the system software shall be capable of supporting five different levels of user, e.g. operator, engineer and system manager, etc. For example:

(a) Operators would be responsible to control and monitor the substation using the facilities of the SCS.

(b) Engineers would be responsible for any fundamental changes made to the SCS software or configuration.

(c) System managers would be responsible for the system security, back-up and database maintenance.

The availability of functions to each user shall be configurable, allowing the user’s area of responsibility to be defined.

The maximum number of different user levels supported and the degree of configuration available of each level shall be stated in the Tender.


8.3.5 System Capacity The design shall meet the following general requirements with regard to capacity and expandability.

The SCS shall be designed, delivered and commissioned with sufficient capacity for performing the requirements of this specification.

The SCS shall be equipped with control, indication and measurement functions required by the Scope of Work.

The maximum system capacity and system loading shall not be less than 200% of the specified system capacity, including the specified future expansion.

In addition to the facilities detailed in the Facility List section, approximately 10% spare input/output capacity shall be provided within the contract (this figure shall be confirmed at the specific site survey in agreement with the Employer’s Representative). These spare facilities shall be fully fitted and pre-wired to the Bay Control Units.

The design shall provide for future expansion, modification and testing with the minimum of disruption to existing facilities.

A minimum of 25% of the future expansion capacity shall be demonstrated during the FAT.

8.3.6 System Performance The SCS scanning and polling frequencies shall ensure the following overall performance. If better performance is necessary to ensure satisfactory operation of certain SCS functions, the Tenderer shall state this.

The SCS shall process, enter into the database and update all relevant displays currently on view within two seconds of a change occurring at a Bay Control Unit input. This time shall include for any calculation or other processing required to enter derived or compiled information into the files, logs, reports or displays.

The SCS shall also process all information required at the NCC (e.g. status, measurements and alarms) and have them available for transmitting to the NCC within two seconds of a change occurring at a Bay Control Unit input.

The elapsed time between selecting a display and the full display appearing on any screen shall be less than one second for 50% of requests, less than two seconds for 90% of requests and less than three seconds for 100% of requests.

The System shall give priority to commands such that commands issued from an operator’s workstation shall have confirmation of action (from the Bay Control Unit) displayed within four seconds of issue from the workstation (not including the time taken for plant to operate).


The SCS shall be capable of handling all alarms and status changes occurring during avalanche conditions without loss of any data. Avalanche conditions are defined as follows:

• A fault on a HV switchgear busbar (resulting in the generation of multiple alarms)

• Occurrence of 100 + 0.1N + √N changes is 5 seconds where N is the total number of data inputs (double signals count as two data inputs).

8.3.7 Software Requirements 8.3.7.1 General The software shall be of modular construction, developed using structured design techniques and written in a commonly used programming language. Where possible, standard library software shall be utilised. The contractor shall identify all standard proprietary software and any software specially developed for this project.

The application software shall ensure the secure execution of SCS functions.

The operator workstation software shall run under a well proven, widely used, industry standard and internationally supported operating system.

8.3.7.2 Real-time database A real-time database shall be maintained within the SCS system. A general check shall be initiated at intervals to retrieve all data points from the remote I/O to ensure validity of database entries. This interval shall be configurable between 30 minutes and 36 hours.

The real-time database shall be open and the data dictionary published.

The real-time database shall support the import/export of data via standard interfaces such as SQL, ODBC, etc.

8.3.7.3 Database management Engineering facilities shall be provided for database and graphic display creation and modification for the operator workstations.

Facilities shall be provided so that the operator workstations can be used as engineering consoles to modify and configure the overall SCS system. It shall be possible to prepare modifications in advance and implement them with minimal disruption to the running system.

8.3.7.4 Data processing In the event of detection of the failure of I/O components, indications and alarms from the previous successful scan of the failed I/O shall continue to be displayed on the operator workstation. However, facilities shall be incorporated to indicate to the operator that the relevant data is not presently being updated.


The system shall have the ability to differentiate between status changes resulting from operator actions and apparently spontaneously occurring actions, the latter drawing attention to the operator via an audible alarm and highlighting the status change on the workstation.

The processing of analogue signals shall include:

(a) Scaling for display in engineering units.

(b) Alarm supervision between adjustable limits, e.g. Low Alarm, Low Warning, High Warning & High Alarm.

(c) Devising values such as summated power flows.

8.3.8 Hardware Requirements 8.3.8.1 General The design of all SCS equipment shall be such as to ensure satisfactory operation in an electrically hostile environment typical of high voltage electrical installations.

Equipment located outdoors shall be suitable for operation in the local environmental conditions and shall be housed in weatherproof kiosk/cubicle protected in accordance with Class IP 55 of IEC 60144 and be dust, insect and rodent proof.

The equipment may be either of single board design or of rack mounted modular construction. All computer equipment shall be supplied with a real-time multi-tasking operating system which conforms to a recognised industry standard and not unique to one manufacturer. Interconnecting cables shall be made via substantial, secure plugs and sockets, which shall be mounted in accessible positions and clearly labelled.

A technical description of each item of equipment, together with evidence to show that the stated guaranteed reliability figures are supported by actual service conditions, shall be supplied with the Tender.

8.3.8.2 Master Control Units The Master Control Unit shall have an interface to a portable maintenance terminal through which it can be configured and operated locally. One portable maintenance terminal shall be provided with the SCS.

The power supply to the Master Control Unit shall either be derived from the plant 48V DC control supply battery or from the UPS specified below depending on its requirements.

8.3.8.3 Remote Communications Interface As a minimum, the SCS device providing the remote communications interface shall support the IEC 60870-5-101 and DNP3 protocols along with any other protocols specifically requested in the Scope of Work. The Tenderer shall provide details in their Tender of the SCADA communication protocols supported by their system.


The Contractor shall be responsible for the design, supply and installation, including the modification of existing plant that may be required for the correct interfacing of SCS equipment with the existing National Control Centre, including all protocols and communications as required. It is essential that the Contractor carries out tests to demonstrate that the full SCADA facilities are available over the communications interface and that the implementation of the standard protocols at the existing NCC Master End and the new SCS are the same.

The rights to access the SCS indications and controls from remote systems shall be programmable within the SCS for each communications link connected to the SCS.

The communication interface shall support dual redundant communication links to remote control sites (NCC) and have the ability to automatically change to a healthy link if one link should fail.

The power supply for this equipment shall provide a 8 hour standby capacity such that it is able to continue to communicate and exchange control and data with the NCC SCADA Master Station in the case of mains failure of the source of supply e.g. mains or charger failure.

8.3.8.4 Bay Control Units Each Bay Control Unit shall be individually programmable for integrated functions such as control, interlocking logic, metering without transducers and status/event/alarm acquisition.

Each Bay Control Unit shall have an interface to a portable maintenance terminal through which each Bay Control Unit can be configured and operated locally. This is in addition to any integral facilities to allow operation from the Bay Control Unit itself.

Generally, one Bay Control Unit shall be provided per switchgear equipment bay. The Bay Control Unit shall generally be located in the relay panel, to provide a suitable environment. Additional Bay Control Units shall be used for substation general alarms and substation services, as necessary, and located so that signals are connected to a Master Control Unit/ Bay Control Unit as close as is practically possible to where those signals are derived.

Power supply to the Bay Control Unit shall be derived from the plant DC control supply and shall provide for an 8 hour standby period in the event of failure of the source supply.

8.3.8.5 Local Control Mimic A Local Control Mimic shall be provided to interface between the Bay Control Unit and the 400 kV and 132 kV plant. It shall contain all facilities for control, indication, local/remote control selection, protection and alarms associated with that switchgear section. A mimic diagram incorporating switches, contactors and relays necessary for local electrical control of circuit breakers, disconnectors and earth switches together with position indication shall be included.

The Local Control Mimic shall enable control of the plant even if the Bay Control Unit is unavailable. The electrical interlocking system will apply to the controls operated from the local control Mimic.


8.3.8.6 Digital Inputs Plant alarms and indications shall be derived from voltage free contacts with the wetting current supplied from the respective SCS input card. Equipment with two normal states e.g. circuit breakers and isolators, shall be represented by two source contacts to provide a positive indication of state, including illegitimate states.

Alarm signals may be derived from contacts that either close momentarily (fleeting) or remain closed for the duration of the alarm condition (sustained).

The change of state of a digital input shall be time tagged to a resolution of 1 ms for Sequence of Events (SOE) reporting.

8.3.8.7 Analogue Inputs Analogue inputs shall be capable of processing standard voltage and milliamp current inputs continuously. The inputs shall be digitised to a resolution of at least 11 bits plus sign bit.

8.3.8.8 Command Outputs Command outputs shall be designed to provide “select and execute” operation. The select output shall energise the interposing control relays allowing the open or close command to actuate the appropriate control relay.

The period of the command pulse shall be configurable between 2 seconds and 30 minutes to allow for circuits with synchronising facilities. The command pulse timer shall reset immediately the command is executed or the synchronising is cancelled.

8.3.8.9 Pulse Counting Inputs Pulse counting inputs shall acquire and count impulses produced by “volt free” contacts, which can be either normally open or normally closed. Pulse counting inputs shall be provided as either a separate input module or using digital inputs.

The accumulative values must be treated as instant analogue values for the purposes of the equipment at the NCC reading the data.

8.3.8.10 CT and VT Inputs Transducer-less inputs with direct connection to CTs or VTs for the measurement of frequency, voltage, current, phase angle, watts, VArs and VA for both single and three phase power circuits shall be provided.

8.3.8.11 Operator Workstations The operator workstations shall be rugged, industrial type units and shall be equipped with a high resolution colour visual display unit (VDU), alphanumeric keyboard and pointing device (mouse/trackball). It shall be possible to increase the number of VDUs per workstation to two or three, although one will be provided under this contract.

The visual display unit (VDU) shall be fitted with high quality Liquid Crystal Display (LCD) to ensure good resolution and clarity of information in all areas of the screen.


The VDU shall have power on/off switch and indicator along with brightness, contrast and any other necessary controls, all of which shall be readily accessible to the operator. It shall be possible to align the colours accurately once installed in its final position.

The pointing device shall enable quick and accurate movement of the cursor on the VDU to designate the selected points on the displays. On workstations with more than one VDU, it shall be possible to freely move the pointer over the contiguous screen area.

The workstations shall be provided with adequate memory for the required tasks with 25 per cent spare capacity.

A highly reliable mass storage device shall be provided in each workstation sized to satisfy the requirements of the operating system, applications software and anticipated stored data plus 40 per cent spare capacity.

Each workstation shall be supplied with a CDROM drive/writer/re-writer for loading software and backing-up/restoring software and data.

The operator workstation shall be equipped with a low level audible alarm.

The operator workstations shall be fully configured and set into operation by the Contractor. This shall include populating the I/O databases and preparing all graphical screen displays necessary to provide a user interface suitable for full operation and monitoring of the substation plant. The design and layout of the screen displays shall be approved by the Engineer.

The workstation shall be provided with an operator’s control desk as follows:

The control desk shall be 75 cm high, double pedestal type of reinforced and stiffened steel construction with flush panelling throughout the knee-hole, sides and front. Each pedestal shall contain one utility drawer with pencil tray and dividers, and one file drawer with two adjustable dividers. Utility drawers shall be mounted on silent-action nylon bearings. File drawers shall be mounted on telescoping tracks with ball bearing rollers. Drawer pulls shall be bright chromium plated. All steel panelling and drawers shall receive two coats of baked enamel finish throughout the exposed interior and exterior surfaces.

Desk tops shall be finished in plastic laminate, firmly bonded to the substrate. The tops shall have a 10 cm high plastic laminate edge banding finished flush with the side panels and drawers. A 20 cm high plastic laminate finished base shall extend all around the desk perimeter and pedestals also flush with side panels and drawers.

Enamel and plastic laminate colours shall be as selected by the Engineer.

8.3.8.12 Printers All printers shall be high performance and of robust construction, suitable for continuous duty.

The maximum noise level for the operation of any printer is 50 dB (A). The printers shall contain off-line self-test facilities that allow adjustment and maintenance without interfering with the remainder of the computer system.


Printer consumables shall be readily available locally in Iraq.

All printers shall be A4 size and print on single sheets. The printers shall hold at least 500 sheets of paper and a paper low alarm shall be provided at the SCS workstation. The on demand logging printers shall be black and white laser type. The colour printer shall be ink jet type.

8.3.8.13 Local Area Network The substation control system shall utilise a high speed optical fibre LAN that conforms to recognised industry standards for the interconnection of SCS equipment.

The LAN shall be complete with all necessary repeaters, bridges, routers, etc., required for the operation of the SCS equipment.

The Tenderer shall state in their tender submission the protocol used by their proposed LAN.

8.3.9 Environmental Performance 8.3.9.1 Atmospheric Environment 8.3.9.1.1 Temperature The standard nominal range of ambient temperature shall be -10°C to +55°C.

The protection system shall operate satisfactorily when tested to the following requirements:

IEC 60068-2-1 with severity class -10°C, 96 hours

IEC 60068-2-2 with severity class 55°C, 96 hours.

The protection system shall be able to withstand the temperature requirements for storage and transportation and shall be tested to the following requirements: -



8.3.9.1.2 Relative humidity: The protection system shall operate correctly with a relative humidity of 93 per cent and shall be tested to IEC Publication 6068-2-78 with severity class 56 days.

8.3.9.1.3 Enclosure: The protection relay shall meet the requirements of the tests detailed in IEC 60529 with classification IP50 (dust protected). If the individual enclosure of the relay is to a class less than IP50 then the Tenderer shall provide a cubicle to classification IP50 to accommodate the relay.


8.3.9.2 Mechanical Environment 8.3.9.2.1 Vibration: The protection system shall meet the requirements of the tests detailed in IEC 60255-21-1 with severity class 1.

8.3.9.2.2 Shock and Bump: The protection system shall meet the requirements of the tests detailed in IEC 60255-21-2 with severity class 1.

8.3.9.2.3 Seismic: The protection system shall meet the requirements of the tests detailed in IEC 60255-21-3 with severity class 1.

8.3.9.3 Electrical Environment 8.3.9.3.1 DC auxiliary energising quantity: The protection systems shall be capable of being energised from a dc auxiliary energising voltage of 110 V (nominal).

The protection system or its associated power supply for use in a 110 V (nominal) dc supply system shall operate correctly over a voltage range of 88 V to 132 V and shall withstand a maximum voltage of 143 V.

Numeric protection systems shall meet the requirements of IEC 60255-11 with interruptions to the dc auxiliary energising quantity of 10 mS.

8.3.9.3.2 Frequency: The standard rated frequency shall be 50 Hz.

The nominal range of frequency shall be -5 per cent to +5 per cent.

8.3.9.4 Insulation 8.3.9.4.1 Rated insulation voltage: The rated insulation voltage of circuits connected to current transformers of high impedance relays shall be 1000 V. All other circuits shall have an insulation voltage of 250 V.

All open contacts of the protection system shall withstand a voltage of 1000 V.

8.3.9.4.2 Dielectric tests: The protection system shall comply with the dielectric test requirements of IEC 60255-5. The test voltage shall be selected according to the rated insulation voltage of the circuits being tested form Series C of Table 1 of IEC 60255-5.


8.3.9.4.3 Impulse voltage: The protection system shall comply with the impulse test requirements of IEC 60255-5 with test voltage of 5 kV.

8.3.9.5 Electromagnetic Compatibility The requirements of this section of the specification are specifically applicable to numeric protection systems. The requirements may also be applied to some electro-mechanical relays that are very sensitive or of high speed, at the discretion of the Engineer.

8.3.9.5.1 1 MHz burst disturbance: The protection system shall comply with the requirements of IEC 60255-22-1 with severity Class III.

8.3.9.5.2 Electrostatic discharge: The protection system shall comply with the requirements of IEC Publication 60255-22-2 with severity Class III.

8.3.9.5.3 Radiated electromagnetic field disturbance: The protection system shall comply with the requirements of IEC 60255-22-3 with severity Class III. The test shall be carried out by using Test Method A and by sweeping through the entire frequency range 27 MHz to 500 MHz.

8.3.9.5.4 Fast transient disturbance: The protection system shall comply with the requirements of IEC 60255-22-4 with severity level IV.

8.3.9.5.5 Electromagnetic Emissions The protection system shall comply with IEC 60255-22-25.

8.3.10 Uninterruptible Power Supply An uninterruptible power supply (UPS) is required to power the SCS components in the substation control room such as the Master Control Unit and the operator workstations.

This shall either be from an Inverter fed from the station 50 volt battery system, and this is preferred, or from a stand alone UPS system. For the Inverter solution, the Tenderer shall state the increased battery capacity required to support the control room equipment such that an 8-hour standby capacity for the SCS is maintained.

The Inverter solution shall comprise an inverter, static by-pass switch and manual maintenance by-pass.

The UPS system shall comprise a rectifier/charger with maintenance-free sealed batteries, inverter, static by-pass switch and manual maintenance by-pass.


8.3.10.1 Modes of Operation The following requirements apply to both Inverter and UPS solutions except that the battery/charger comments will not apply to the Inverter solution.

• Normal

The inverter shall continuously supply the load. The UPS rectifier/battery charger or station 48v battery shall supply dc power to the inverter and the UPS batteries will simultaneously be maintained in a fully charged condition. The static by-pass switch shall be synchronised to the mains by-pass supply frequency so that an automatic change-over does not cause an interruption to the load.

• Overload

In the event of an overload, the static by-pass switch shall automatically switch the load to the raw mains by-pass supply. The static by-pass switch shall automatically switch the load back onto the inverter when the load current returns to a normal level, without interruption.

8.3.10.2 Mains Supply Failure In the event of mains supply failure to the UPS; the inverter shall draw its power from the UPS battery. For the inverter solution, the load will continue to be fed from the station 48v battery via the Inverter. There shall be no interruption to the load when mains power is restored. When power is restored, the UPS rectifier/charger shall recharge the UPS battery without any interruption to the load. The ampere-hour capacity of the UPS battery shall be adequate to support the equipment for a period of at least 8 hours in the event of a loss of supply.

8.3.10.3 Static By-Pass Switch In the event of a failure of the rectifier/charger, battery or inverter, the load shall be automatically switched to the raw mains by-pass supply using the static by-pass switch. This transfer shall not cause an interruption to the load. It shall also be possible to initiate a manual changeover to the by-pass if required, e.g. for maintenance.

8.3.10.4 Manual Maintenance By-Pass A manual by-pass facility shall be available to switch the load to the raw mains supply to facilitate maintenance and repair of the UPS system and batteries, or Inverter. Transfer to and from the manual by-pass shall not cause an interruption to the load.

8.3.10.5 Control and Instrumentation The UPS and Inverter shall have a local control panel to show the status of the key parameters and mode of operation of the system. The principle indications and alarms shall be:

(a) Mains input V and I

(b) inverter output V and I


(c) battery V

(d) rectifier alarms (UPS only)

(e) inverter alarms

(f) load alarms

Remote indication of the ‘general alarm’ status of the UPS/Inverter system shall be provided for annunciation in the substation control room and at the SCS.

8.3.11 Maintenance and Spares The intended maintenance strategy for the SCS is that the Employer will be able to:

(a) perform ‘first-line-maintenance’ of all subsystems, i.e. be able to locate faulty hardware components and replace them with spare parts with the faulty parts being returned to the original equipment supplier for repair or replacement

(b) analyse and define software faults and protocol interface problems with NCC

(c) re-configure and extend the SCS facilities with minimal assistance being necessary from the original equipment supplier, including updating databases, modifying and building new display screens and adding new equipment and devices to the SCS

Spare parts for the SCS shall be provided to support the maintenance strategy described above, particularly bearing in mind the ‘turn around time’ to repair/replace faulty components.

The Tenderer shall include an itemised and individually priced list of recommended spare parts in their offer. It is anticipated that this list would include at least one item of each hardware component used within the SCS for use in first-line-maintenance (or 10% of the components for components that occur in larger numbers within the system, e.g. I/O cards). Any special tools, including software and hardware (e.g. lap-top computers) maintenance tools shall also be itemised. The Employer shall be at liberty to purchase any numbers of those items at the tendered price until 3 months after contract placement.

8.3.12 Documentation Documentation for the SCS shall be provided in line with the general provisions specified in the Tender documentation. The documentation shall include the complete functional specification of all hardware and software and complete maintenance and user manuals for both hardware and software. In particular, the maintenance documentation shall include detailed fault finding flow charts to assist with first line maintenance of all subsystems and the user manuals shall provide detailed instructions on system configuration such that the Employer may re-configure and extend the SCS facilities without assistance being necessary from the original equipment supplier.

Complete and original copies of all software programmes, operating system, drivers, data bases, tools, and emulators etc shall be provided on CD.


8.3.13 Training Training of the Employer’s operations and maintenance personnel shall be provided to the levels required to enable them to safely and competently operate the SCS and to maintain the system to the levels described.

It is anticipated that 4 weeks of formal structured training courses will be provided locally on site (courses to cover both hardware and software). The operational “hands on” aspects of this may take place during the 500 hour Trial Period. In addition ‘on the job’ training shall be provided, whereby two of the Employer’s software engineers work alongside those of the equipment supplier at the equipment supplier’s factory for a period of 4 weeks during the configuration stages and continuing on site during the commissioning stages.

Details of the training shall be provided to identify the type or training, the training locations and the numbers of personnel to be trained, which in any case shall not be less than four for the on site training. All expenses associated with the training including international and local travel, hotel accommodation and meals and sundry expenses for all the trainees shall be included.

8.3.14 Warranty and Support. The Warranty Period shall be as stated in the contract conditions and ongoing support for the SCS shall be available for a minimum of five years after Taking over of the Works.

The Tenderer shall provide details of maintenance agreements, including prices, for the various levels of support that may be purchased after the completion of the Warranty Period.

8.4 Facilities to be provided to the SCS for Substation and NCC

8.4.1 General The following facilities are the minimum that shall be provided to the SCS. Where specific plant and equipment has facilities that are additional to these, they shall be included at no additional cost to the Employer. The facilities that shall be provided by the SCS at the substation, and those that are transmitted to/from the NCC, shall be agreed with the Employer using the Overall Facility Schedule and based on the NCC Standard Facility List, during the engineering phase of the Contract. The agreed Overall Facility Schedule shall then be used to configure the SCS and used as a basis for SCS testing.


8.4.2 Facility List

CONTROLS/COMMANDS 400 kV Circuit Breaker Trip Close 11 kV tertiary reactor capacitor bank circuit breaker Trip Close 400 kV Disconnect Switch Open Close 400 kV Auto Transformer On Load Tap Changer Raise tap Lower tap 132 kV Circuit Breaker Trip Close On test 132 kV disconnect switch Open Close 400 and 132 kV Feeder Auto Reclose In Service Out of Service INDICATIONS/STATUS 400 kV Circuit Breaker Open Closed On test 11 kV tertiary reactor capacitor bank circuit breaker Open

Closed 400 kV Disconnect Switch Open Closed 400 kV Earth Switch Open Closed 400 kV Auto Transformer On Load Tap Changer Tap position Auto (man) Master/Follower 132 kV Circuit Breaker Open Closed 132 kV disconnect switch Open Closed 132 kV Earth Switch Open Closed 400 and 132 kV Feeder Auto Reclose In Service


Out of Service ALARMS 400 kV Circuit Breaker Breaker trip Breaker fail protection operated CT stack protection operated Auto reclose operated Auto reclose successful SF6 pressure falling SF6 pressure low lock out Low operating oil pressure Gas heater fail (SF6) Trip circuit fail 400 kV Disconnect Switch Transformer disconnect switch opening automatically Transformer disconnect switch out of step Feeder disconnect switch opening automatically Feeder disconnect switch out of step 400 kV Feeder Distance trip - Group A Distance trip - Group B Overcurrent trip Back up protection Earth fault trip PLC channel fail Directional earth fault trip Direct transfer trip received Permissive transfer trip received Block signal received SF6 pressure falling SF6 pressure low lock out Protection fail - Group A Protection fail - Group B 110 V DC fail PT voltage fail 400 kV Feeder Reactor Line reactor trip - Group A Line reactor trip - Group B Overcurrent trip Earth fault trip Differential trip Buchholz stage 1 – gas alarm

Buchholz stage 2 – trip


Oil temp stage 1 – alarm Oil temp stage 2 – trip Winding temp stage 1 - alarm Winding temp stage 2 - trip Low oil Neutral reactor O/C Neutral reactor Buchholz stage 1 – gas Neutral reactor Buchholz stage 2 – trip Neutral reactor temp stage 1 - alarm Neutral reactor temp stage 2 - trip Neutral reactor low oil SF6 pressure falling SF6 pressure low lock out 400/132 kV Auto Transformer Transformer Distance trip Overcurrent trip Earth fault trip 400 kV differential protection operated 132 kV differential protection operated SF6 pressure falling SF6 pressure low lock out Transformer Buchholz stage 1 – gas alarm Transformer Buchholz stage 2 - trip Tapchanger Buchholz stage 1 – gas alarm Tap changer Buchholz stage 2 - trip Transformer low oil stage 1 Transformer low oil stage 2 Tap changer low oil stage 1 Tap changer low oil stage 2 Tap changer gas pressure relay Transformer oil temp stage 1 400/132 – alarm Transformer oil temp stage 2 400/132 – trip Winding temp stage 1 400/132 - alarm Winding temp stage 2 400/132 - trip Transformer cooling fail On Load Tap Changer HI/LO limit On Load Tap Changer Out of step On load Tap Changer Protection trip Transformer protection fail - Group A

Transformer protection fail - Group B


Tap change incomplete Transformer 11 kV winding/busbar protection trip Transformer 11 kV winding/busbar differential trip Transformer 11 kV winding/busbar overcurrent trip Transformer 11 kV winding/busbar earth fault trip Tertiary reactor protection trip Tertiary reactor differential trip Tertiary reactor overcurrent trip Tertiary reactor Buchholz stage 1 - alarm Tertiary reactor Buchholz stage 2 - trip Tertiary reactor low oil Tertiary reactor oil temp stage 1 – alarm Tertiary reactor oil temp stage 2 – trip Tertiary capacitor bank protection trip Tertiary capacitor bank overcurrent trip Tertiary capacitor bank unbalance trip Earthing transformer protection trip Earthing transformer low oil Earthing transformer oil temp stage 1 - alarm Earthing transformer oil temp stage 2 - trip Services transformer protection trip Services transformer low oil Services transformer Buchholz stage 1 - alarm Services transformer Buchholz stage 2 - trip Services transformer oil temp stage 1 –alarm Services transformer oil temp stage 2 – trip 400 kV Busbar Differential trip Bus protection operated Bus protection fail SF6 pressure falling SF6 pressure low lock out Protection fail (CT secondary circuit fail) 110 V DC fail Communications PLC equipment fail Back up combs equipment fail PABX fail Fuse failure (composite)

Communications equipment alarm (composite)


132 kV Feeder Line protection trip Back up protection trip Distance trip Overcurrent trip Earth fault trip Breaker fail protection operated Transformer trip received (if required) Auto reclose operated Auto reclose successful or definite tripping Permissive transfer trip received SF6 pressure falling SF6 pressure low lock out Gas heater fail (SF6) Trip circuit fail PT voltage fail PLC channel fail Pilot circuit fail 110V DC fail 132 kV Bus coupler Overcurrent trip Earth fault trip SF6 pressure falling SF6 pressure low lock out Breaker fail protection operated 132 kV Bus section Overcurrent trip Earth fault trip Breaker fail protection operated SF6 pressure falling SF6 pressure low lock out 132 kV Bus bar Busbar protection operated Differential trip Protection fail (CT secondary circuit fail) 110V DC fail SF6 pressure falling SF6 pressure low lock out 132 kV Transformer Transformer Distance trip Overcurrent trip Earth fault trip

Differential trip


Breaker fail protection operated Winding temp stage 1 - alarm Winding temp stage 2 - trip Earthing transformer trip E/F SF6 pressure falling SF6 pressure low lock out Fire Alarm Fire alarm (each zone) Fire alarm faulty (each zone) Station General Station common fail Load shedding Stage 1 Load shedding Stage 2 Load shedding Stage 3 Fault recorder operated Fault recorder fail Station General Undervoltage alarm ac station service section No 1 Undervoltage alarm ac station service section No 2 Station Services Transformer No.1 trip Station Services Transformer No.2 trip Diesel generator protection operated Diesel generator running 110V charger fail (composite) 110V battery earth fault (composite) 110V battery alarms (composite) 110V DC station service section A undervoltage 110V DC station service section B undervoltage 48V charger fail (composite) 48V battery alarms (composite) 48V DC station service section A undervoltage 48V DC station service section B undervoltage Low frequency Substation Control System faulty Annunciator alarm fuse fail Domestic Water Tank Low water level Microwave tower lighting fail Packaged A.C. unit stopped (per unit) Switchgear/cable basement fan(s) stopped Battery Room extract fan failure A.C. filter assembly blocked A.C. fire/smoke detector energised A.C. return air temperature high Sandstorm monitor warning


ANALOGUE MEASUREMENTS 400 kV Feeder KV Amps MW MVAr 400 kV Busbar kV 400/132 kV Auto Transformer – 400 kV kV Amps MW MVAr OLTC position 400 kV Feeder Reactor MVAr 11 kV tertiary kV MVAr Amps Station voltage (400 kV) kV Station frequency Hz 132 kV Feeder kV MW MVAr Amps 132 kV Busbar kV 400/132 kV Auto Transformer – 132 kV kV MW MVAr Amps 132 kV Bus section Amps 132 kV Bus Coupler Amps Station voltage (132 kV) kV ENERGY IMPULSES 400 kV Feeder MWh export MWh import 400/132 kV Auto Transformer MWh export MWh import Station total MVAh MVAh export Station total MWh MWh export Station total MVArh MVArh export

Station total MVAh

MVAh import


Station total MWh MWh import Station total MVArh MVArh import 11 kV tertiary MVArh MVArh export MVArh import 11 kV tertiary - Station MVArh Summated MVArh export MVArh import 132 kV Feeder MWh export MWh import 132 kV Transformer MWh export MWh import Auxiliary Transformer MWh

9-1


9. PROTECTION REQUIREMENTS

9.1 General

9.1.1 Background This section describes the functional performance requirements of the protection system to be supplied. Numeric protection relays are required and these may be in addition used to provide Integrated Protection and Control – see section 8.3.1Introduction in the Control, Indications, Measurements and Annunciation section, above.

The specification refers to specific discrete protection functions and it is accepted that with numeric relays these may be provided by common hardware.

The Contractor shall be fully responsible for all necessary coordination works regarding the protection equipment, with other contractors if necessary.

This section assumes the provision of conservator type main and tertiary transformer and reactors and the Tenderers ability to offer particular designs or protective system. If the Tenderer wishes to offer alternative schemes which perform equivalent duties then he shall provide complete details of the scheme proposed in accordance with the instructions to Tenderers.

Single line diagrams of a typical 400 kV substation diameter and a 132 kV double busbar showing ac connections and protection are included in the Specification. The relevant diagrams are standard for all 400 and 132 kV GIS and AIS substations.

A diameter is defined as the series of three circuit breakers connected between two busbars providing two circuit bays in the 1-1/2 breakers substation configuration. The typical diameter shows one line and one transformer. For diameters with two lines the transformer circuit is appropriately replaced with line protections.

Proven equipment shall be provided and evidence of site experience shall be provided by the Tenderer.

The primary network shall be considered as consisting of a number of elements, the limits of each element being its associated circuit breakers.

For the 400 kV network, each element shall be provided with two sets of high-speed discriminative protection, capable of detecting all "credible" faults and issuing tripping commands to the associated circuit breakers within the prescribed time. "Credible" faults shall include all faults whether phase/phase or phase/earth irrespective of whether maximum or minimum plant is connected, account being taken of the fault impedance. "Non-credible" faults are those involving a second order plant failure, for example, a broken conductor lying on high resistance ground and for which extended fault clearance time may be acceptable. Each set of discriminative protection (Group A and Group B) shall be physically and electrically separate with respect to dc supplies, current transformer cores, voltage transformer windings and multicore cables.

9-2


High-speed discriminative protection systems shall be engineered as complete schemes, due account being taken of CT and VT (or CVT) performance. The defined fault clearance time shall take account of the circuit breaker response and shall include the total time to elimination of the primary fault current irrespective of the magnitude, fault location or fault current characteristic subject only to an upper limit of circuit breaker specified duty.

Attention shall be paid to the total performance including the behaviour pattern in the presence of system transients for faults "in zone", faults "out-of-zone", and during the period immediately following a switching operation irrespective of whether that operation is to eliminate a network short-circuit or is to energise or to de-energize any part of the network.

The protective equipment shall remain un-operated following the normal and correct discharge operation of one or more surge arresters.

9.1.2 Extent of Supply This section covers the minimum design requirements of the types of protective relay functions. The Contractor shall be responsible for co-ordinating the parameters of each device, circuit or system within the contract, and to arrive at a total compatible overall system. In addition, the work shall include manufacture, inspection and testing at makers works, packing for export, shipment, insurance, delivery to site, installation, electrical connections, testing commissioning and setting to work the equipment specified in this section.

9.1.3 Discrimination On the occurrence of a fault on the power system network high speed discriminating protection systems shall rapidly detect the fault and initiate the opening of only those circuit breakers which are necessary to disconnect the faulted electrical element from the network. Protection equipment associated with adjacent electrical elements may detect the fault, but must be able to discriminate between an external fault and a fault on the electrical element which it is designed to protect. Sequential time delayed tripping is not permitted except in the following specific circumstances.

(a) Operation of time graded back-up protection takes place as a result of either the complete failure of the communication links associated with the main protection systems, or the fault resistance is substantially greater than the value specified in section 1.2.8.1.12 of this specification.

(b) Operation of line back-up protection to disconnect primary system faults in the case of a circuit breaker failing to operate, (i.e. circuit breaker failure protection).

All back-up protection systems shall be able to discriminate with main protection systems, circuit breaker fail protection and with other back-up protection systems installed elsewhere on the transmission system.

9-3


9.1.4 Objective Fault Clearance Times The existing Iraq system objective maximum fault clearance times, based on a nominal circuit breaker trip time to arc extinction of three cycles – 60 mS, are as follows, however, it is expected that modern equipment will provide reduced timings and the figures in (brackets) should be aimed at:

400 kV

(a) Six cycles – 120 mS - Local end line faults and plant faults. (80 mS)

(b) Seven & Half cycles – 150 mS - Remote line faults using permissive trip. (100 mS)

(c) Nine cycles – 180 mS - Remote terminal faults using direct transfer trip.

(d) Sixteen cycles – 320 mS - Breaker fail protection with direct transfer trip.

132 kV (300 mS).

(a) Nine cycles – 180 mS - Local end line faults, plant faults, and bus faults

(new sites provided with bus zone protection)

(b) Twelve cycles – 240 mS - Remote line and remote plant faults requiring direct transfer trip

(c) Twenty-five cycles approximately – 500 mS - All other faults, including those busbar fault covered in Zone 2 of line distance protection.

The individual relay operating times should be as fast as possible and consistent with overall reliability. For both system voltages, the reduced overall fault clearance times will be preferred.

9.1.5 Protection System Construction and Mounting Protection systems shall preferably be accommodated in 19 inch rack or hinged rack cubicles and be of modular construction with factory assembled and tested wiring. The construction method shall offer the benefits of minimum site construction times and circuit outage requirements.

For modular protection systems, means shall be provided to lock positively each withdrawable module or unit in the "service" position. It shall not be possible to remove any module without first short-circuiting all associated current transformer circuits.

A portable colour printer and note-book type computer complete with all software required by each protection relay shall be provided.

Modular relays (e.g. rack mounted numeric relaying equipment) shall be tested as a complete assembly and details of such tests shall be agreed with the Engineer when details of the construction are known.

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All relays which are accommodated in cubicles having a separate cubicle door shall be provided with individual relay covers. This requirement is to enable access to indication reset facilities without also allowing unauthorised access to relay setting adjustments.

For extension to existing installations, all new relay panels shall match the existing method of construction and installation as closely as possible.

9.1.6 Indications Each relay or protection scheme shall be provided with an adequate number of indications to ensure that the appropriate faulted phase, zone, etc can be easily identified after a fault condition. Each indicator shall be visible and capable of being reset without removing the relay cover. Unless otherwise approved, indications shall only be given by the protection(s) causing the fault to be cleared.

Where illuminated indicators are used (e.g. light-emitting diodes) the following shall apply:

(a) Long term storage of the indication must not be dependent upon an auxiliary supply

(b) A lamp test facility shall be provided.

9.1.7 Contacts Each protection relay or protection scheme shall be provided with an adequate number of output contacts of suitable rating to carry out the prescribed tripping functions, alarms, indication and fault recorder functions and such supplementary signalling functions as may be necessary for the initiation of automatic reclosing or automatic switching control, etc. In all cases, contacts intended for tripping duty shall be designed so that they cannot inadvertently interrupt trip coil current.

For contacts intended to be used to energise circuit breaker trip coils directly, information shall be provided to show that the contact rating is compatible with the trip coil parameters of the associated circuit breaker. Where appropriate, details shall also be given of the operating characteristics of any reinforcing contactor and, in particular, the pick-up and drop-off threshold levels of series connected (current dependent) contactors.

9.1.8 Numeric Relays Numeric protection relays shall utilise numerical techniques for both measurement and logic functions and in addition to the main protection functions, shall incorporate communication; fault, event and disturbance recording; instrumentation; configurable scheme logic; alternative setting groups and self-supervision facilities.

The communication facility should allow all information available locally at the relay front panel to be accessed remotely. It should also be possible to carry out bulk transfer of settings, fault record information etc using the appropriate PC based software.

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All facilities necessary for the interconnection of the protection relays and for communication with the individual relays from a central location shall be provided e.g. fibre optic cables, coupling and interface devices etc.

All protection systems shall be provided with an integral local operator interface facility to enable communication with the relay without the use of external equipment. Any facilities provided for connection to an external computer shall be an additional feature to the local operator interface.

The protection relay shall also be supplied with the facilities identified below:

(a) Identification: Each protection system shall have a unique identifier which is clearly visible and the software reference and issue level shall be identified.

(b) Settings: Each protection system shall provide a means by which the user can easily access the protection system to apply the required settings, which shall be password protected and secure from inadvertent operation. A display of the selected settings shall be provided on the protection system.

(c) Indications: Each protection system shall provide indications appropriate to its facilities.

(d) Time Synchronisation: Each distance protection relay shall be capable of being synchronised to an external time source derived from a GPS receiver, shared with the SCS.

9.1.9 Trip Circuit Supplies Tripping supplies for Group A and Group B protection schemes for each 400 kV circuit shall be derived from separate sections of the main dc distribution board such that under normal circumstances, each protection scheme is supplied from a different battery and each protection scheme utilises a separate trip coil on the circuit breaker.

9.1.10 Trip Circuit Supervision and Auxiliary Supply Monitoring Means shall be provided to continuously supervise the integrity of the circuit breaker tripping circuits and give an alarm in the event of the following fault conditions: -

(i) Loss of dc tripping supply, e.g. opening of trip supply MCB removal of dc trip link, etc.

(ii) An open circuit in the trip circuit including the trip coil, circuit breaker auxiliary switch and all associated connections (supervision to be effective with the circuit breaker in either the open or closed condition).

The alarm shall be time-delayed to prevent it operating during momentary dips in the dc. supply. The alarm shall also be inhibited when the circuit breaker auxiliary switch interrupts the trip coil circuit, on circuit breaker opening.

All auxiliary supplies, ac and dc, essential for the operation of the protection relay scheme shall be monitored and the loss of any supply shall be indicated on the relay panel and an alarm given.

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9.1.11 Commissioning and Routine Testing Facilities Each functional relay scheme shall be so arranged that operational and calibration checks can be carried out with the associated primary circuit(s) in service.

Adequate test facilities shall be provided within the protection system to enable the protection and auto-reclosing equipment to be tested from the front of the protection equipment with the primary circuit(s) in service.

Adequate facilities shall be provided to isolate all dc. and a.c. incoming and outgoing circuits, together with ct shorting/disconnecting links, so that work may be carried out on the equipment with complete safety to personnel and without loss of security in the operation of the switching station.

All test equipment required for commissioning and routine testing of the offered protection equipment shall be listed in the tender documents. Where test equipment is specified, it shall include such injection transformers, test leads and plugs as are necessary to carry out secondary injection tests on each type of relay scheme and, for the more complex schemes, such special test equipment as may be necessary to verify the accuracy of timing and verify the effective operating characteristics of the equipment.

For numeric equipment, such test equipment as may be required to carry out on-site investigation into the performance of individual modules or printed circuit cards shall be listed in the tender documents. At least one complete set of any special test equipment shall be included within this Contract together with such additional connections, dummy extension boards, etc as may be necessary.

9.1.12 Relay Settings Not less than 6 months before commissioning, suitable settings shall be recommended for all relays and protection to be supplied. The recommended settings will ensure satisfactory operation in accordance with the intent of this Specification and the specified system operating conditions. The recommended setting shall not only include those normally available on the front of a relay but also the positions/settings of any internal links, plugs, etc not normally adjusted after installation. These settings shall be applied to the equipment prior to performing the commissioning tests. The settings for line protection shall be such as to permit correct operation of the protection for earth faults up to 100 ohms fault resistance. Any limitations imposed on the power system as a result of the settings proposed shall be explicitly stated.

9.2 Environmental Performance

9.2.1 Atmospheric Environment 9.2.1.1 Temperature The standard nominal range of ambient temperature shall be -10°C to +55°C.

The protection system shall operate satisfactorily when tested to the following requirements:


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The protection system shall be able to withstand the temperature requirements for storage and transportation and shall be tested to the following requirements: -



9.2.1.2 Relative Humidity The protection system shall operate correctly with a relative humidity of 93 per cent and shall be tested to IEC Publication 6068-2-3 with severity class 56 days.

9.2.1.3 Enclosure The protection relay shall meet the requirements of the tests detailed in IEC 60529 with classification IP50 (dust protected). If the individual enclosure of the relay is to a class less than IP50 then the Tenderer shall provide a cubicle to classification IP50 to accommodate the relay.

9.2.2 Mechanical Environment 9.2.2.1 Vibration The protection system shall meet the requirements of the tests detailed in IEC 60255-21-1 with severity class 1.

9.2.2.2 Shock and Bump The protection system shall meet the requirements of the tests detailed in IEC 60255-21-2 with severity class 1.

9.2.2.3 Seismic The protection system shall meet the requirements of the tests detailed in IEC 60255-21-3 with severity class 1.

9.2.3 Electrical Environment 9.2.3.1 DC Auxiliary Energising Quantity The protection systems shall be capable of being energised from a dc auxiliary energising voltage of 110 V (nominal).

The protection system or its associated power supply for use in a 110 V (nominal) dc supply system shall operate correctly over a voltage range of 88 V to 132 V and shall withstand a maximum voltage of 143 V.

Numeric protection systems shall meet the requirements of IEC 60255-11 with interruptions to the dc auxiliary energising quantity of 10 mS.

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9.2.3.2 Frequency The standard rated frequency shall be 50 Hz.

The nominal range of frequency shall be -5 per cent to +5 per cent.

9.2.4 Insulation 9.2.4.1 Rated Insulation Voltage The rated insulation voltage of circuits connected to current transformers of high impedance relays shall be 1000 V. All other circuits shall have an insulation voltage of 250 V.

All open contacts of the protection system shall withstand a voltage of 1000 V.

9.2.4.2 Dielectric tests The protection system shall comply with the dielectric test requirements of IEC 60255-5. The test voltage shall be selected according to the rated insulation voltage of the circuits being tested form Series C of Table 1 of IEC 60255-5.

9.2.4.3 Impulse voltage The protection system shall comply with the impulse test requirements of IEC 60255-5 with test voltage of 5 kV.

9.2.5 Electromagnetic Compatibility The requirements of this section of the specification are specifically applicable to numeric protection systems. The requirements may also be applied to some electro-mechanical relays that are very sensitive or of high speed, at the discretion of the Engineer.

9.2.5.1 1 MHz Burst Disturbance The protection system shall comply with the requirements of IEC 60255-22-1 with severity Class III.

9.2.5.2 Electrostatic Discharge The protection system shall comply with the requirements of IEC Publication 60255-22-2 with severity Class III.

9.2.5.3 Radiated Electromagnetic Field Disturbance The protection system shall comply with the requirements of IEC 60255-22-3 with severity Class III. The test shall be carried out by using Test Method A and by sweeping through the entire frequency range 27 MHz to 500 MHz.

9.2.5.4 Fast Transient Disturbance The protection system shall comply with the requirements of IEC 60255-22-4 with severity level IV.

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9.2.5.5 Electromagnetic Emissions The protection system shall comply with IEC 60255-22-25.

9.2.6 Thermal Requirements The requirements of this section apply to protection systems rated at 1 A associated with line circuits where the load current is carried by current transformers which supply the protection system.

The protection systems shall have a minimum continuous thermal withstand of 2.4 A.

The thermal withstand currents for short duration overloads, after having reached a steady temperature with an input current of 2.0 A, shall not be less than given in the table shown below.

Duration (mins) 20 10 5 3 2 Current (amps) 3.10 3.5 4.0 5.0 6.0

9.3 Protection/Relay Types

9.3.1 Distance Protection 9.3.1.1 General Distance protection for 400 kV feeders shall comprise two sets of distance relays, each distance relay providing at least three forward and one reverse zone of protection; 400 kV distance protection shall operate in conjunction with teleprotection channels operating over various communications media.

The 400 kV distance protection relays and teleprotection channels shall form:

- a permissive under reaching transfer tripping scheme

- an overreaching blocking scheme.

The 400 kV protection schemes shall be:

(i) Suitable for complete simultaneous multi-phase and earth fault three zone measurement. Phase selection and sequential measurement are not acceptable.

(ii) Suitable for single pole and three pole tripping and auto-reclose operation.

(iii) Suitable for application on a double circuit line, i.e. include mutual zero sequence compensation.

(iv) Provided with power swing blocking facilities suitable for blocking zones 1, 2, 3 as required.

(v) Provided with an integral distance to fault locator.

(vi) Provided with an integral directional earth fault protection function.

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Overcurrent starting will not be accepted. However, schemes employing overcurrent elements that act as a check to prevent maloperation of the measuring elements during line de-energisation or resetting measuring elements during single-pole auto-reclose dead time are acceptable.

Only equipment having extensive field experience at 400 kV will be accepted. Tenderers shall provide a reference list of such projects for which the equipment has been used.

For the 400 kV feeder circuits, each set will be energized from separate current and voltage transformer secondary windings via separate multicore cables.

Both 400 kV distance protection relays shall have facilities for independently tripping duplicate circuit breakers and initiating auto-reclosing, breaker failure protection, intertripping, alarms, fault locators, fault recorders etc.

The Tenderer must guarantee that any distance relay offered will operate satisfactorily under the conditions described herein and with the distance relays at the remote substation.

Each distance relay shall operate for all types of phase and earth faults. Separate phase and earth fault distance measuring elements shall be provided; separate elements shall also be provided for each zone. Phase and earth fault compensation features shall be incorporated to ensure accurate distance measurement for all types of faults and to allow for the variation in the path of earth faults on the system.

Cross-polarized mho relays are preferred for zone 1 and 2 elements and these shall operate only for faults in the protected line direction. Under no circumstances shall the relay operate for reverse faults even when the voltage supplied to the relay falls to zero on all three phases, nor shall they operate due to the transient response of the line capacitive voltage transformers during or following the clearance of close-up faults behind the relay. Details of methods used for polarizing relays to deal with all types of faults close to the relaying point shall be provided. The relay characteristics shall ensure adequate fault resistance coverage under minimum plant and single outage conditions. Zone 3 shall be non-directional and shall be capable of being independently off-set in both directions. No measuring element shall operate during normal system switching or during de-energisation of the transmission line.

The relay characteristic of impedance measuring starting relays shall cover the protected line plus the longest line emanating from the remote station taking current in-feed into account. This requirement will be relaxed at the Engineer's discretion in the case of extremely long lines. The starting relays shall not operate during maximum power transfer. When single phase to earth faults coincide with maximum power transfer, only the starting or measuring relay associated with the faulted phase shall operate. The starting relays can be employed as zone 3.

On long lines the minimum load impedance presented to the relay during maximum power transfer may encroach an offset mho zone 3 characteristic. Zone 3, therefore, (and any associated power swing blocking characteristics, if applicable) shall be capable of being shaped to avoid load impedance.

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The reach of each measuring zone and starting relay shall be individually adjustable. The characteristic angle shall be adjustable between approximately 60 and 85 degrees.

Zone 2 and zone 3 shall have time delay setting ranges of 0 – 1.5 seconds and 0 -3 seconds respectively.

The sensitivity of the protection shall be adequate for definite operation under minimum plant conditions and single outage conditions and shall not exceed 30 per cent rated current.

The operating time of each zone shall be substantially independent of fault current magnitude. Curves shall be provided showing the effect on operating time of line and source impedance, fault position and operating current and point on wave of fault application.

A switch on to fault feature shall be incorporated to ensure instantaneous tripping in the event that the circuit breaker is closed onto a fault on a previously de-energized line.

The switch onto fault feature in the relay proposed for use in the permissive under reach transfer tripping scheme shall also be capable of being enabled during the auto-reclose dead time. This is to ensure fast clearance of non-transient end zone faults where delayed zone 2 clearance would normally occur when the local end is reclosed before the remote end.

The distance protection shall include a voltage transformer supervision unit to prevent possible unwanted operation of the distance relay comparators in the event of a failure of one, two or three phases of voltage caused by open or short circuit faults in the voltage transformer secondary circuits or due to removal of VT fuses. In the event of loss of one, two or three phases the distance relay shall be blocked and a time delayed alarm initiated.

The VT supervision shall not operate during energisation of the line or of any power system transformers, during a single pole reclose cycle nor during any other power system primary disturbance. It shall also be inhibited during a single pole auto reclose cycle to ensure there is no delay in tripping remaining poles if a second fault occurs during the single pole dead time.

The VT supervision unit shall be faster than the distance relay measuring units under all circumstances.

Teleprotection channels over Power Line Carrier and other communications media will be used in conjunction with the distance relays to form:

- A permissive under reaching transfer trip scheme.

- An overreaching blocking scheme.

Supply and installation of cables from the protection relay panels to the main and standby teleprotection equipment included in the scope of work of this contract.

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A separate fully adjustable timer, delayed on reset shall be provided to delay the resetting of the blocking signal received during fault current reversal conditions on a parallel circuit. The Tenderer shall recommend a minimum time setting for this timer.

A reverse looking, fast operating element shall be provided for initiating the transmission of the blocking signal. This element shall preferably have an offset mho characteristic to ensure that a blocking signal is definitely sent for any type of fault immediately behind the relay. As the relay will also respond to faults in the forward direction of the protected line, the blocking signal shall be interlocked with the forward looking zone 2 elements and shall not be sent if zone 2 elements operate. Under no circumstances shall a blocking signal be transmitted for faults in front of the relay. Since the reverse looking element must definitely operate for any type of fault behind the relay, its sensitivity must be at least equal to and preferably higher in all respects to the remote end zone 2 overreaching elements.

The distance relays shall incorporate indicators to show the zone in which the relay tripped and phase or phases faulted, whether the relay operation was due to aided trip, switch onto fault, power swing blocking, VT fuse fail or directional earth fault if appropriate. Indication must not be lost in the event of a supply failure.

In addition to sufficient tripping contacts, the protection shall have, where necessary, contacts for initiating single pole and three pole auto-reclosing, two sets of circuit breaker failure protection, fault locators, fault recorders, protection signalling and alarms.

Selection facilities are required to permit or inhibit auto-reclosing if the carrier is or is not in service.

Where appropriate the protection and associated auto-reclose equipment shall incorporate whatever means are necessary to ensure that all measuring and starting elements in the healthy phases of the faulted line and all measuring elements on the parallel circuit remain reset and are unaffected by the fault and load currents which flow in the healthy and parallel circuit during the single phase reclosure dead time. Additionally, the inter-phase fault measuring elements on the faulted circuit shall be stable in the presence of a heavy close-up earth fault. The methods used to ensure correct stability of healthy phase elements during single phase dead times and during fault conditions shall in no way prejudice the ability of the protection and auto-reclosing scheme to respond to faults during the dead time and reclaim time.

Distance relays shall be suitable for single phase reclosing schemes and the contractor shall demonstrate conclusively by conjunctive test and by calculation that phase selective tripping will be achieved under the various system and load conditions described in this section.

The necessary feature shall be incorporated in the relay to inhibit the zone 1 and zone 2 phase fault elements when necessary during single phase to earth faults and during the single pole auto-reclose dead time. Provision shall also be made to ensure the faulty phase earth fault elements definitely reset during the single pole auto-reclose dead time.

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The effect of zero sequence mutual coupling between the double circuit lines on the protection shall be described together with any measures considered necessary to overcome this effect.

The 400 kV distance protection time delayed back-up zones shall be arranged to intertrip the remote station circuit breakers via direct transfer tripping channels. In this case auto-reclosing shall not be initiated.

Design calculations for current transformers for use with distance relays shall be submitted to the Engineer for approval within three months of contract award. CT design shall be based on a maximum fault level equivalent to the 400 kV switchgear rating as appropriate and the X/R ratios equated in this Specification.

9.3.1.2 Supplementary 400 kV Directional Earth Fault Protection To achieve fully discriminative clearance of high resistance earth faults at any point on the protected line, each 400 kV distance protection relay shall incorporate an integral directional earth fault (DEF) element operating in conjunction with teleprotection channels. The DEF protection shall operate either in a permissive overreach or an overreach blocking mode as necessary to match with DEF protection at the remote ends of the line. The DEF protection shall operate for phase to earth and two-phase to earth faults and the blocking scheme shall comprise forward and reverse looking directional earth fault elements. The same teleprotection channels may be used for the directional earth fault protection and the distance protection schemes.

Adjustable time delay units shall be provided for the following: -

(a) to allow the distance protection to operate before the DEF element for earth faults having values of fault resistance which lie within the zone 1 characteristic.

(b) to allow the DEF protection to operate as a back-up earth fault relay to provide remote back-up protection for high resistance faults independently of the carrier equipment. Auto reclosing shall be blocked in this case.

(c) to prevent maloperation during current reversal situations during fault clearance on the parallel line.

(d) to delay the DEF blocking scheme long enough to allow the receipt of a blocking signal for external earth faults.

Each timer shall be clearly labelled to identify its function.

A fixed timer (short delay on drop off) shall also be provided to delay resetting of the blocking signal by about 10 m secs.

DEF protection shall also trip the local circuit breaker three pole. Single pole tripping and single pole auto-reclosing from the DEF scheme is not required. Selection facilities in the form of links or switches shall be provided to either block or allow initiation of the delayed three pole auto-reclose scheme as desired.

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The VT supervision unit associated with the distance protection shall also inhibit the DEF protection in the event of VT fuse failure.

It shall be possible to reset the DEF element by means of a signal from the auto reclose relay during the single pole dead time.

9.3.1.3 Power Swing Blocking The 400 kV distance relays shall incorporate power swing blocking elements.

Power swing blocking elements for distance relays having offset mho zone 3 characteristics or starters shall comprise an offset mho characteristic, which encompasses and is concentric with the distance relay impedance starter or zone 3 characteristics. Similarly where it is possible to shape the zone 3 or starter characteristic the power swing-blocking characteristic shall also be capable of similar shaping.

Facilities shall be provided to block zones 1, 2 and 3 of the distance relay as required and an alarm signal to be initiated.

Blocking logic shall be derived by determining the time taken for the apparent impedance of the power swing locus to pass from the characteristic of the power swing element to the distance relay starter characteristic. Blocking shall not take place until the apparent impedance has passed through the two power swing characteristics and the timer has expired.

The associated time delay relay shall have a setting range of 50 - 250 m secs.

The setting range of the power swing characteristic angle shall at least be adjustable over the same range as the distance relay starting or zone 3 characteristic.

Reset times shall be fast enough to ensure that the distance protection reverts to its normal role as soon as possible following a power swing.

Where applicable, power swing blocking shall be inhibited during the single pole dead time of an auto-reclose cycle so that if a power swing develops during this period the distance protection can give an immediate three phase trip. The Tenderer shall advise whether it is possible to extend the inhibition of the power swing blocking to cover a period immediately following auto-reclosing so that if a power swing develops on reclosing onto a permanent fault a three-phase trip would be permitted. The Tenderer shall also advise whether power swing blocking can be inhibited if an earth fault occurs during a power swing.

If the associated VT supplies are lost due to VT fuse failure, the power swing blocking element shall not operate.

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9.3.1.4 Fault Location Equipment Each 400 kV distance relay shall incorporate an integral fault location facility, which shall indicate the approximate distance between the line terminal and the fault. The fault locator shall preferably be of the reactance measuring type so that the loop impedance measurement is not affected by fault arc resistance. Measurement at each line terminal shall be independent of any measurement made at other terminals.

The fault locator element shall be fast in operation and shall have an accuracy such that the maximum error of any measurement will not exceed ±3 per cent of the total line length, irrespective of the total fault clearance time.

Determination of the fault position shall be as simple as possible. A direct reading digital display, calibrated in percentage distance of the total line length, is preferred.

If it is practicable to do so, automatic recording of the measurement shall be provided. If not, the measured information shall be capable of being stored, with no increase in error, for a period of not less than 100 hours.

The current and voltage transformer performance characteristics to adequately cover the performance of the fault location element during the worst "in service" conditions shall be specified.

The maximum required measuring time for the specified accuracy shall be smaller than the time available during the fastest anticipated fault clearance time.

9.3.1.5 Distance Protection Test Equipment To facilitate automatic testing of the feeder distance protection relays to be carried out regularly and rapidly and with a minimum of disturbance to relay equipment, the Tenderer shall include one set of programmable computer controlled automatic test equipment. This is to include computer unit, keyboard, monitor, general purpose software, software for testing operation in a single pole tripping scheme, etc.

9.3.2 Inverse Time Overcurrent and Earth Fault Relays Inverse time overcurrent and earth-fault relays shall be of the numeric type and shall have selectable characteristics, i.e. normal inverse, very inverse and extremely inverse.

The operating time characteristic shall be continuously variable over the minimum range 0.1 to 1.0 times the nominal time at any multiple of current setting.

The current settings shall be adjustable as a percentage of nominal relay rating over setting ranges which are at least:

overcurrent relays - 50 to 250%

earth-fault relays - 10 to 100%

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The actual relay pick-up current shall not exceed 1.3 times the relay setting and the reset value shall not be less than 90 per cent of the pick-up current.

All relays shall comply with the accuracy requirements of Clause 7 of IEC 60255-4, the required class index of the reference limiting error being 5.

9.3.3 High Set Overcurrent, Instantaneous Overcurrent and Earth Fault Protection

High set overcurrent, instantaneous overcurrent and earth-fault protection shall be of the numeric high-speed type and shall have a current independent selectable time delay with a setting range from instantaneous (no intentional time delay) to 100secs in steps of 0.01secs.

High set overcurrent elements shall be of the low transient overreach type, i.e. the magnitudes of the current with and without the presence of a dc transient at which operation occurs shall be approximately the same. The value of the system reactance to resistance ratio at which the performance of the element is claimed should be stated. When applied to the protection of power transformers, high set overcurrent elements must be capable of being set to remain stable for maximum through fault currents associated with faults across the remote winding terminals.

The high impedance principle may be used to obtain stability of the instantaneous earth-fault protection.

9.3.4 Directional Relays Directional relays may either be provided as separate numeric relays or as part of an overcurrent or earth-fault inverse-time relay combination.

A range of characteristic angle settings shall be provided so that correct directional discrimination will be achieved for all credible system faults. Preference will be given to relays in which voltage polarising, current polarising or dual polarising can be achieved.

Where directional features are applied to overcurrent and earth-fault inverse-time relays, the following requirements apply:

(a) the operating time of the directional element shall have negligible influence on the total operating time of the composite relay

(b) The current setting of the directional element shall be low enough so as not to increase the overall setting of the composite relay for all faults in the operate direction.

9.3.5 Overcurrent and Earth Fault Definite Time Lag Relays Preference will be given to relay designs in which the current settings for phase to phase faults are the same as those for three phase faults and in which the current settings for single phase to earth faults are the same irrespective of the phase involved.

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The current measuring elements shall be of the low transient overreach type and the value of the system reactance to resistance ratio at which the transient overreach performance claim is made shall be stated. Their operating time shall be less than 30 milliseconds at 5 times setting and their drop-off to pick-up ratio shall not be less than 90 per cent.

The associated timing relay shall have a timing range (or ranges) adjustable between 0.1 and 10 seconds minimum, the setting adjustment being either continuous or stepped, with a maximum of 20 milliseconds per step. The accuracy of setting shall be at least ± 5 per cent of setting or 20 milliseconds whichever is the greater.

9.3.6 Circulating Current Protection The protection shall remain unoperated for all out-of-zone fault currents ranging from 0 to 15 times full load rating of the protected circuit and all other system transient conditions, such as in-rush currents, which are not due to internal faults.

The protection shall remain stable for all out-of-zone faults with fault currents up to the short circuit rating of the switchgear, applied suddenly or gradually. The protection sensitivity shall be such as to ensure that definite operation of the protection occurs for all phase-to-phase and phase-to-earth faults under minimum plant conditions, irrespective of the number of circuits in service and the distribution of load and fault currents.

The operating time shall be 30 ms or less at 5 times setting.

Care shall be taken to ensure that the protection does not maloperate as a result of faults in the associated secondary wiring when the primary circuit is carrying load current. Continuous or automatic cyclic supervision shall be provided for this purpose. Where the operation of the supervision device is dependent upon the load current in the primary circuit, operation shall occur at a current of 25 amperes or 10 per cent of the circuit rating whichever is the greater.

The Contractor shall submit all the necessary data required to prove the predicted performance of the protection.

9.3.7 Multi-Contact Tripping Relays All multi-contact tripping relays shall be suitable for panel mounting. The design of the operating coil shall be such as to permit operation in conjunction with series trip flag relays should these be specified. When provided on the relays, economy contacts used to reduce the level of energisation of the operating coil after operation shall be delayed in operation sufficiently long enough to ensure that series flag relays operate correctly.

All contacts shall operate within the prescribed time for the particular category which shall not, in any case, exceed 10 milliseconds from the time at which the operating coil is first energised to the time of complete contact closure.

Where lockout relays are specified, these must be of the mechanically latched type and shall be hand/electrically reset as specified.

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9.4 Protection Functions

9.4.1 400 kV Primary Line Protection Systems Two primary line protection systems shall be provided based on multizone, multielement phase and earth fault distance protective relay schemes, to be operated independently and in parallel. Each system shall be supplied by separate CT and V.T. windings and fed by a separate DC supply system, and act on a separate trip coil per phase basis. Where “diameter” CTs are summated to provide feeder current inputs to protection, the ct cores and lead burdens shall be matched.

9.4.2 400 kV Main Line Protection - Group A Provide main line protection - Group A with the following features:

- Three zone phase and earth fault mho or suitably shaped characteristic distance scheme utilising offset mho or equivalent elements for starting and backup purposes (depending on the requirements of the relays offered), and high speed tripping when closing on to a faulted line. Suitable contacts for use in a permissive underreach transfer trip (acceleration) scheme shall be provided.

- DC auxiliary supplies and tripping circuits on the “A” battery

- Four separate trip outputs: One per phase giving a single output on the faulted phase for zone 1 or accelerated single-phase to earth faults, and suitable for use with single pole auto reclosing. One three phase trip output for all multi phase faults and all timed clearance zone 2 or 3 faults, and suitable for three pole high speed or delayed auto reclosing.

- Complete reset of high speed trip measuring circuits, after arc extinction has occurred on the open phase of the faulted circuit following single pole tripping but high speed tripping should be provided if the fault develops to multi phase.

- A setting range for the zone 1 impedance measuring element of 50 per cent to 120 per cent of line length on all protected lines.

- A setting capability for zone 2 overreach protection to give typically 125 per cent of each line length with a time delay in the range 0-1.5 seconds.

- Zone 3 protection time delay range of 0-3.0 seconds with a setting range to cover at least 200 per cent of the protected line length.

- Blocking of relay tripping in the event of loss of V.T. supplies on one or more phases to the relays.

- Facilities for addition of power swing blocking.

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- A sensitive directional comparison earth fault protection shall be provided using a separate protection signalling circuit and having additional logic to “echo” for returning the comparison signal if the remote end is open, or other wise to ensure fast tripping for high resistance earth faults over the whole feeder length, even if the remote end of the circuit is open.

- Timer for protection delaying of 0.1-0,6 range and for echo logic circuit to be alive of 0.2-1 second range shall be provided.

9.4.3 400 kV Main Line Protection Group B Provide main line protection - Group B with the following features:

DC auxiliary supplies and tripping circuits on the “B” battery supply.

Same basic features as Group A protection but of different design, thus allowing both systems to give complete coverage and reduce the possibility of protection failure due to any inherent weaknesses, and to provide full line protection if protection Group A is out of service.

The requirements for a different design may be met by provision of a blocked overreach distance protection rather than the combination of a permissive underreach and directional earth fault scheme system specified for Group A.

The system should provide fast tripping over the whole line length even when the remote end is open, and should also have underreach protection capability for fast clearance of local end line faults.

9.4.4 400 kV Line Protection Signalling Equipment Line protection signalling equipment shall provide facilities as follows:

- Provide separate permissive transfer trips using a fast simple logic code for the Group A earth fault distance and the directional comparison earth fault protections.

- The receipt of the appropriate protection signal shall operate through the respective protective system logic and phase selection facilities to provide fast phase and earth fault protection and to initiate single pole or three pole reclose.

- For maximum security provide a complex code for the direct transfer trip signal to trip the remote end circuit breaker. The receipt of the signal shall energise all three phases of both trip coils of the appropriate circuit breakers.

- Initiate the direct transfer trip signal from the line reactor protections and from the circuit breaker failure protections and from the CT stack protections.

- Provide a blocking signal for the overreach distance protection, where provided.

- Provide separate 110 V dc interposing relays, one for each sending and receiving signal for each of the duplicated signals in the “A” and “B” panels. The two contact system shall be used to provide most immunity to the relay interconnections from interference.

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9.4.5 Allocation of 400 kV Line Protection Signalling Channels The direct transfer trip signals shall be given first priority in any priority coded signalling scheme and shall be duplicated on separate routes. The logic will be such that the receive output will be given continuously if a send condition is maintained at the remote end, and immediately cut off when the sending end condition is removed.

The blocking signal for any overreach distance scheme shall use the power line carrier channel over its own protected transmission line while the permissive transfer trip will use an alternatively routed channel. Both systems will have second priority (if appropriate) within their signalling systems.

Directional Comparison Earth Fault signals shall be duplicated over the two separate routes and shall be given third priority on both systems. The comparison signal will be sent after protection time delaying only.

If duplicate underreach distance schemes are provided then both A and B groups of line protection will initiate and receive in parallel permissive direct transfer trip signals using both signalling routes.

9.4.6 400 kV Line Reactor Protection Provide two groups of line reactor protection allocated to the appropriate groups as follows:

Group A

Phase and earth differential protection as appropriate to match with the current transformers on the reactor, and overcurrent protection.

Gas surge (Buchholz) protection, oil level low and oil over temperature protection for the main phase and neutral reactors operating into “B” battery circuits.

Group B

A neutral current instantaneous alarm and about 10 second delayed trip in the neutral reactor earth connection operating into “A” battery circuits.

9.4.7 400 kV Tripping & Auto Reclose Logic Provide tripping and auto reclose logic according to the following principles:

A high speed single pole auto reclosing scheme having no current or voltage check, other than a cancel signal provided from the associated protection three pole trip circuits which will reset any reclose that is in the process of timing out.

A three pole auto reclose scheme giving high speed reclose without synchro-check facilities and delayed reclose.

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A delayed three pole auto reclose with voltage check and duty selection facilities to enable dead line charging and/or dead bus charging and/or synchronism check for live line reclosing. The delayed auto reclose equipment shall work in conjunction with the voltage selection and synchronising equipment specified.

Reclosure shall only take place on overhead line circuits and shall be initiated following tripping by the distance relay zone 1 equipment or following an aided trip in the permissive under reach transfer trip scheme or in the blocking scheme. Reclosure shall not be initiated in the event of a three-phase fault, any type of fault in the second or third back-up zones or when the circuit breaker is closed onto a fault on a previously de-energized line.

For 400 kV overhead line circuits, three pole delayed auto-reclosing may also be initiated by the supplemental directional earth fault protection.

All circuit breaker and protection signalling operation devices shall seal in to ensure that complete breaker operation occurs and that the protection signalling equipment remote receive relays operate, but then release to allow auto reclose to proceed. The use of time delayed reset latching relays in those parts of the circuit not applicable to high speed single pole reclose would be acceptable.

Each 400 kV circuit breaker shall have both single pole high speed and three pole reclose logic separately with separate time settings for single reclose, for three phase high speed reclose and for three phase delayed reclose.

Single and three pole reclosure is to be prevented on circuit breakers that were open prior to the fault.

All single pole trip outputs initiate single pole reclosing following tripping of the appropriate phase.

All three pole trips prevent single pole reclosing on the affected circuit breakers.

If more than one pole trip output occurs, this shall initiate a three pole trip and inhibit single pole reclosing.

Three pole trips initiated at any stage during any reclose operation cause immediate trip of any closed phases and achieve three phase trip.

Three pole trips initiate three pole reclose where selected unless cancelled by a local circuit breaker fail, trip on energising, phase disagreement, backup overcurrent, direct transfer trip receipt or a local line reactor trip. Reclosing onto a fault shall lock out further reclosure, during the reclaim time.

Three pole reclose will be interlocked to prevent it from operating if a local trip relay has not reset or if the appropriate circuit breaker is not able to reclose.

Line reactor protection, circuit breaker fail protection or CT stack protection operation on line circuit breakers will initiate direct transfer trip signal to the remote end of the line.

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Selector switches shall be provided on the appropriate relay panel to enable the following duties to be selected: -.

Selector switch 1 shall allow one of the following options to be selected: -

(i) High speed single pole reclose: This will select single phase auto reclose for a single phase fault. (For multi phase faults a three phase trip will occur with no reclose).

(ii) Single pole and three pole reclose: this will allow either a single phase reclose for single phase faults or a three phase reclose for a multi phase fault, dependant on the type of fault.

(iii) Three phase reclosure for all types of fault.

(iv) Reclose off.

Selector switch 2 shall select the type of three phase auto reclose cycle required:

(i) High speed three phase reclose

(ii) Delayed three phase reclose.

Facilities shall be provided for switching the auto reclose equipment out of service from both the relay panel and the SCS.

Provide an operation counter to record separately the number of operations for single pole and three pole trips and to lock out after a pre-selected number of protection trips have been recorded.

Relays shall offer the following ranges of the high speed and delayed reclosing dead times: -

High speed single pole reclose dead time: 0.3 to 3.0 seconds.

Delayed three-pole reclose dead time: 3 to 30 seconds.

The Tenderer shall state the available ranges.

The reclaim time shall be chosen to match the duty cycle of the circuit breakers, assuming the shortest available dead time is chosen. The reclaim time shall not, however, be less than 10 seconds, and the reclaim timer range shall extend to 180 seconds. The duration of the closing command shall be limited to two seconds, after which time the reclosing equipment shall be automatically reset without resetting the reclaim timer. The reclosing equipment shall also reset if dead line check, dead busbar check or synchronism check conditions are not satisfied within five seconds of the check relays being energised.

A signal shall be provided from the dead line check relays for interlocking of the line earth switches to prevent the switches being closed on a live line.

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9.4.8 400 kV Substation and Back Up Protection 9.4.8.1 400 kV Overcurrent Back-up Protection In Group A protection IDMT overcurrent back-up protection operating into “A” battery circuits shall be provided using inverse time overcurrent relays connected in each line and transformer circuit. This protection shall trip all three poles of the associated circuit breakers by trip coil “A” and prevent all auto reclose equipment on those circuit breakers from operating.

Three phase over current relays and one residual overcurrent relay shall be provided. Three phase over current relays are to be over-loading protection having a setting range of 1 –2.5 times of nominal current of the line or transformer. The neutral overcurrent relay shall give back up for faults and it shall be very sensitive (0, 1 to 1 times of the nominal current).

Each inverse definite minimum time (IDMT) relay shall have an instantaneous element which shall be brought out to a separate trip output which shall be disconnectable.

The provision of definite time overcurrent relays will be considered if the Contractor can show that suitable settings and coordination can be achieved.

9.4.8.2 400 kV Circuit Breaker Fail and Malfunction Protection Circuit breaker fail protection shall be provided which shall clear a fault which has been correctly detected by the appropriate protection but for which the associated circuit breaker(s) has (have) failed to open, as follows:

(a) It shall operate for initiation by a trip signal on any phase of either trip coil of each circuit breaker on a breaker by breaker basis.

(b) Provide a timer with a range 50 to 200 ms and a fast resetting current check relay adjustable to minimum fault current infeed for faults, on either side of transmission circuit breakers, but thermally rated to meet the full breaker thermal rating.

(c) Provide circuits in Group B to three pole trip the next in line circuit breakers by trip coil “B” from “B” battery DC supply and to initiate both direct transfer trip channels to any appropriate remote circuit breakers following the detection of a breaker failing to trip on fault.

(d) Provide interconnection into the busbar differential protection B group trip circuit bus to trip all circuit breakers connected to the busbar on which the stuck circuit breaker is located

(e) Provide a mechanical phase disagreement trip, either as part of or external to the circuit breaker control circuits, to effect a three pole trip if one pole has been open for more than a given time. Time delay setting range shall be 1 to 5 seconds.

(f) The protection must be effective during single pole tripping cycles and must not operate during the single pole open conditions prior to single pole reclose.

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(g) For software embedded circuit breaker fail protection, one detector function shall be utilised. For discrete relay (e.g. non-software embedded) circuit breaker fail protection system shall comprise two independent circuit breaker fail relays. Each circuit breaker fail relay comprising a current detecting and time delay element. Coincident operation of both circuit breaker fail relays shall be arranged to initiate tripping of the appropriate busbar section.

(h) Two basic criteria shall be satisfied before each circuit breaker fail relay can initiate a trip output. Fault current must be flowing and the appropriate protection must have failed to reset within a preset time. Initiation of a circuit breaker fail trip condition should therefore be dependent on both the preset time elapsing and the current detecting elements being operated, outputs from both these functions being effectively connected in series.

(j) The scheme shall be fast reset and shall provide an acceptable safety margin for current circuit breaker operation taking into account any pre-insertion resistor switching provided.

(k) The settings of the current detecting elements shall be equal to or lower than the settings of the associated protection.

(m) The continuous current rating of the current detecting elements shall be at least twice their nominal current rating, the current settings selected being the lowest available.

(n) The resetting time of the current detecting elements on cessation of fault current shall not be greater than 20 ms. The current detecting circuits must be arranged so that, when single pole tripping is specified, correct operation of the scheme occurs during the dead time, i.e. the presence of load current in the healthy phases should not cause maloperation-operation of the scheme.

9.4.8.3 400 kV Busbar Protection Duplicated phase by phase circulating current differential protection relays (low impedance preferred) shall be provided, one for Group “ A” and one for Group “B”, as follows:

(a) Facilities shall be provided for disconnecting and shorting manually the CT circuit of any feeders from the bus protection CT ring Busbars.

(b) Supervision shall be provided to monitor low level CT unbalance and, after a time delay of about 2 to 3 seconds, it shall provide an alarm and block the busbar differential protection.

(c) The protection must remain stable for external fault currents equal to the breaking capacity of the circuit breakers with an adequate safety factor. System X/R ratio should be considered for the performance of the protection scheme. The relay circuit must have adequate thermal rating. Protection isolation facilities should be provided. Where a high impedance scheme is chosen, means shall be provided to limit over voltages.

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(d) The busbar protection shall operate for both phase-to-phase and phase-to-earth faults. The principle of operation shall be based on the simple circulating current system. The operating time of the measuring relays shall not exceed 30 m secs at five times the relay current setting. The sensitivity shall be such that definite operation occurs for phase-to-phase and phase-to-earth short circuits during minimum plant conditions, irrespective of the number of circuits in service and the distribution of load and fault currents. The sensitivity level shall not exceed 30 per cent of the minimum fault level for all types of faults.

(e) The equipment shall be stable for all out-of-zone phase-to-phase and phase-to-earth fault currents up to the short circuit current rating of the switchgear, applied gradually or suddenly and irrespective of the distribution of current between the individual circuits.

(f) All circuit breakers connected to a faulty busbar shall be tripped simultaneously, whether they feed fault current or not.

(g) Care shall be taken to ensure that the protection does not maloperate as a result of faults in the associated secondary wiring when the primary circuit is carrying load current. Continuous or automatic cyclic supervision shall be provided for this purpose. Arrangements shall be provided to make the zone containing the faulty circuit inoperative. Where the operation of the supervision device is dependent upon the load current in the primary circuit, operation shall occur at a current of 25 amperes or 10 per cent of the circuit rating whichever is the greater.

(h) The following test and isolation facilities shall be provided on the front of the protection panel.

(i) Short circuiting and isolation of current transformers.

(ii) isolation of individual tripping and inter-tripping circuits.

(iii) Isolation of tripping and individual zones.

(j) Direct transfer tripping, where required, shall be affected by means of electrically separate outputs. The inter-tripping scheme shall be to the approval of the Engineer.

(k) Any Isolator auxiliary switches employed in current transformer circuits shall be of the heavy duty; silver plated type and two switches in parallel shall be used per current transformer connection. The Contractor shall clearly specify the number of secondary circuits which must be switched, the duty of the switches and the timing between individual switches; the Contractor shall be responsible for selecting switches which are adequate for the intended duty.

(m) Similar protection zones shall be provided to overlap areas between plant, bus and feeder protection systems, particularly during temporary stages of substation development.

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9.4.9 400/132 kV Auto Transformer & Associated Equipment Protection 9.4.9.1 400 kV Transformer Main Windings The transformers may be supplied as a single unit or as a bank of three phase units. If single phase units are used, the neutral end and tertiary connections shall be connected such that the protection scheme works in the same way as single units. Multiple initiating devices e.g. Buchholz etc shall provide a common trip function, but the individual phase initiations shall be alarmed.

Phase by phase circulating current differential protection shall be provided for the auto transformer and the 400 kV bus connection using identical ratio current transformers on the 400 kV, 132 kV and individual phase neutral connections. Numerical low impedance relays are preferred. Two sets of relays shall be provided. One set shall be connected to Group B fed by the “B” battery supply and the other set of relays shall be connected to Group “A” and operating into the “A” battery supply. When the 400 kV disconnect switch is open this protection scheme will be split into zones. Due consideration shall be given to the performance of the protection scheme under both primary operating conditions. Consideration shall be given to providing two identical relays fed from the all of the relevant CTs. Their tripping functionality shall then be adjusted by the state of the disconnector to meet the objectives above and to provide”stub end” protection to the transformer h.v connections when the transformer is disconnected.

On the 400 kV side a low transient overreach instantaneous overcurrent protection and an IDMT phase by phase backup overcurrent protection shall be provided on Group “A” operating into the “A” battery supply. This may be provided as part of the 400 kV Substation Protection – Overcurrent Back Up Protection specified above.

On the 400 kV side instantaneous and IDMT residual overcurrent protection shall be provided for Group “A”.

A minimum of two step distance protection for Group “A” fed by the 400 kV side CT and P.T. facility shall be provided to catch faults to the transformer direction, without to both direction sensing. The first step reach shall be about 70% of the transformer impedance, the second step about 125%.

Early make late break silvered contact auxiliary switches shall be provided specifically designed and approved to switch current transformer circuits or suitably monitored disconnected position relay (Mirror relays) on the transformer 400 kV disconnect to split the high impedance circulating current transformer protection into two zones when the disconnect switch is open.

Additional contacts shall be provided to interrupt the tripping between 400 kV to 132 (and vice-versa) when this disconnect switch is open. Provide tripping circuits trip the 400 kV, 132 kV, tertiary 11 kV and both 380 V circuit breakers when the 400 kV disconnect switch is closed and only those on the appropriate side of the disconnect switch when it is open. This functionality may be provided within the numerical relay.

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Group B transformer Buchholz protection and the two stages of the 400 kV and 132 kV winding temperature (hot spot simulator) instrument connected to warning and urgent alarms but with the urgent stage reconnectable to trip the l.v only, if required, shall be provided.

Where “diameter” CTs are summated to provide transformer current inputs to protection, the ct cores and lead burdens shall be matched.

9.4.10 132 kV Transformer Protection Group B circuit breaker fail protection shall be provided to trip the 400 kV circuit breakers and the appropriate 132 kV bus protection trip circuit if the 132 kV circuit breaker fails to operate on fault. The protective equipment to be similar to that provided for the 400 kV circuit breakers but needs to be suitable for single trip coil three phase trip breakers only.

L.V. IDMT phase and residual over current relays shall be provided on the transformer Group “A” protection to trip the 132 kV circuit breaker only.

A minimum of two step distance protection shall be provided as specified in Clause (a) above, but fed by 132 kV side C.V. and P.T.

9.4.10.1 11 kV Tertiary Winding The tertiary winding of the 400/132 kV auto transformers is connected to an interconnected star (zigzag) earthing transformer having primary star point earthed, or alternatively for unloaded tertiaries, one corner of the tertiary may be earthed via the main winding protected earth connections. These connections shall be easily accessible on site.

Group “A” individual phase by phase and separately residual high impedance circulating current differential protection shall be provided for the 11 kV Busbar fed by the 11 kV bushing CT of the Main Transformer (only the phase protection), the tertiary Reactor CT and the capacitor bank CT, if provided. Care shall be taken when setting the protection, to take account of the large current imbalance possible when subjected to external earth faults (e.g. from the capacitor or reactor).

If neither tertiary reactor nor capacitor bank is supplied, provide instantaneous overcurrent protection for Group “A” fed by the 11 kV bushing CT.

Group “B” IDMT overcurrent protection relays shall be provided on the main tertiary phase connections and earth fault IDMT protection in the earthing transformer neutral connection to earth using the “B” battery supply.

Group “B” IDMT and instantaneous overcurrent and earth fault protection shall be provided for the Station Supplies Transformer.

Group “B” transformer Buchholz protection shall be provided for the Station Supplies and Earthing Transformers, and an oil temperature and oil level stage 2 trips if it is available.

Circuits to make the above protections trip into the appropriate transformer trip circuits shall be provided.

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Overcurrent and neutral overcurrent protection shall be provided on the 380-volt side of station service transformers to trip the 380-volt circuit breakers, settings to be coordinated with fuse settings. The 380-volt circuit breakers to also be tripped from transformer protection.

9.4.10.2 Tertiary Compensation Plant Group “A” individual phase by phase high impedance circulating current differential protection shall be provided together with IDMT and instantaneous overcurrent and earth fault protection for the tertiary reactor and if oil filled reactor are provided Buchholz relay, oil temperature and oil level protection on Group “B”

Group “A” IDMT and instantaneous overcurrent and earth fault protection and Group “B” capacitor unbalance protection for the capacitor bank shall be provided.

Trip circuits shall be provided from the main transformer protections to both tertiary circuit breakers, optionally switchable.

9.4.11 132 kV Line Protection The following types of system, based on the circuit types to be protected, shall be provided. The specific format of the feeder to be protected shall be set out in the Contract Scope of Work. The actual equipment used will be chosen according to the design and setting ranges of the equipment offered.

9.4.11.1 132 kV Overhead Line Feeders For overhead line feeders, phase-fault and earth-fault distance protection using permissive underreach transfer trip shall be provided. Facilities required for three pole auto reclose shall be provided. The relay shall be designed not to trip for the high zero sequence circulating currents which occur during single pole open conditions on the overlying 400 kV supergrid (duration not to exceed 2 seconds). Facilities for fast tripping if a circuit breaker is closed onto a three phase solid fault when a line is energised shall be provided.

Time delayed (zone 2) tripping shall be provided for a fault occurring at the remote end of a line when (1) the signalling channel is out of service or (2) the remove end of the circuit is open and initiation of permissive signalling is not possible. Zone 2 should be capable of providing protection for any remote end busbar faults.

Zone 3 or starting offset mho elements (depending on the requirements of the relay offered) with an additional time delayed tripping output adjustable between 1 and 3 seconds shall be provided. This trip output shall not initiate auto reclosing. Zone measuring elements setting ranges to be as per 400 kV distance protection, but with extended Zone 3 reach where long lines follow short lines.

For overhead line feeders less than 10km in length, the Tenderer shall confirm that the Distance Protection offered will operate correctly for the length of feeder specified, based on the System Impedance Ratio and fault level, otherwise a pilot wire differential protection shall be offered.

Where the feeder is a mix of overhead line and cable, the Scope of Work will detail this to allow the Tenderer to offer a suitable solution.

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9.4.11.2 132 kV Cable Feeders Cable circuits shall be provided with pilot wire differential protection. Auto reclose on cable circuits will not be required.

The protection may operate over optical fibre or twisted pair route pilot wires and this will be set out in the Scope of Work.

9.4.11.3 132 kV Transformer Feeders “Transformer Feeders” relates to substations where the line is terminated directly onto a transformer without a 132 kV coupling circuit breaker between it and another circuit, i.e. no other line starts from the transformer substation.

Overhead line and cable transformer feeder circuits shall be protected as for standard feeders above, except that duplicated station to station direct transfer trip shall be provided. The distance protection shall be set to measure part way into the transformer.

If no remote 132 kV transformer circuit breaker is specified, duplicated direct transfer trips shall be provided for the remote transformer protections. A fault throwing switch shall be provided if no independent and reliable duplicated DTT can be constructed.

9.4.11.4 132 kV Backup Protection Circuit breaker fail protection shall be provided to trip the appropriate 132 kV bus protection trip circuit if the 132 kV circuit breaker fails to operate on fault. The protective equipment to be similar to that provided for the 400 kV circuit breakers but needs to be suitable for single trip coil three phase trip breakers only.

Three pole phase and one residual IDMT overcurrent relays shall be provided. Each relay shall be provided with an instantaneous element which shall be brought out to a separate output terminal.

These relays shall not initiate auto reclose when they operate with IDMT elements although the instantaneous elements should be connectable to initiate reclosing.

These relays shall be connected to the same current transformer core as used for instrumentation provided the burden limits are not exceeded.

Additional remote backup facilities may be specified for pilot protected circuits which feed busbars having no fast bus protection.

9.4.11.5 132 kV Auto Reclose This equipment should work in conjunction with automatic voltage selection and synchronising equipment specified.

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Three pole high speed and delayed auto reclose facilities shall be provided, optionally switchable by a two position selector switch located on the relay panel. The high speed auto reclose shall be provided with a dead time range of about 0.2 to1 second, without synchro check facilities. The relayed auto reclose shall be provided with voltage and synchro check and with a dead time range of 1 to 6 seconds. Auto reclose shall be initiated by line protection only.

Facilities shall be provided for switching the reclose equipment out of service on local relay panels and the SCS.

Auto reclose operated, auto reclose successful and final trip indications shall be provided.

9.4.12 132 kV Busbars 9.4.12.1 132 kV Busbar Protection A selectable, phase by phase, busbar discriminating, bus protection with check facilities shall be provided (numeric, low impedance is preferred) so that both the discriminative and check feature must operate to give a trip output, as follows:

(a) The busbar protection shall operate for both phase-to-phase and phase-to-earth faults. The principle of operation shall be based on the simple circulating current system. The operating time of the measuring relays shall not exceed 30 msecs at five times the relay current setting.

(b) Duplicated functionality shall be provided either by separate algorithms within one numerical relay (preferred) or by separate Discriminating and Check facilities for each busbar section. Each system shall be capable of detecting all types of faults under all system generation conditions.

(c) This scheme shall only require one set of three phase CTs per circuit, but with separate cores if required.

(d) There shall be fully discriminative clearance of busbar faults on any section of busbar and without introducing sequential tripping of coupler or section circuit breakers on the 132 kV double busbar. All circuit breakers connected to a faulty busbar shall be tripped simultaneously, whether they feed fault current or not.

(e) Facilities shall be provided to prevent incorrect tripping should the CT selection circuits fail to transfer correctly during On-Load changeover.

(f) Care shall be taken to ensure that the protection does not maloperate as a result of faults in the associated secondary wiring when the primary circuit is carrying load current. Continuous or automatic cyclic supervision shall be provided for this purpose. Arrangements shall be provided to make the zone containing the faulty circuit inoperative. Where the operation of the supervision device is dependent upon the load current in the primary circuit, operation shall occur at a current of 25 amperes or 10 per cent of the circuit rating whichever is the greater.

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(g) The following test and isolation facilities shall be provided on the front of the protection panel.

(i) Short circuiting and isolation of current transformers.

(ii) Isolation of individual tripping and inter-tripping circuits.

(iii) Isolation of tripping and individual zones.

(h) Direct transfer tripping, where required, shall be affected by means of electrically separate outputs. The inter-tripping scheme shall be to the approval of the Engineer.

(j) The sensitivity shall be such that definite operation occurs for phase-to-phase and phase-to-earth short circuits during minimum plant conditions, irrespective of the number of circuits in service and the distribution of load and fault currents. The sensitivity level shall not exceed 30 per cent of the minimum fault level for all types of faults.

If a high impedance scheme is offered, it must operate as follows:

(a) If required, the Discriminating system associated with each busbar section is unique, however the Check system is common to all busbar sections.

(b) This scheme shall only require one set of three phase CTs per circuit, but separate cores for discriminative and check circuits (if required), and be capable of correcting for circuit CTs of different ratios. With such a scheme, primary tapped 132 kV current transformers would be acceptable. If a scheme using the high impedance principle is proposed, the circuit CTs must have secondary taps with bus protection cores having identical ratios and suitable characteristics.

(c) Each system shall comprise relays connected in parallel across busbar protection CT bus wiring.

(d) The Check system shall be connected in parallel across the busbar protection CT bus wiring associated with all incomers and feeders. Each Discriminating system shall be connected in parallel across the busbar protection CT bus wiring associated with feeders, incomers, bus coupler and bus section circuits connected to a particular busbar-section.

(e) Coincident operation of the Check system relay and the Discriminating system relay shall be arranged to initiate tripping of the appropriate busbar-section.

(f) Supervision relays shall be provided to monitor low level CT unbalance and to give time delayed alarm and protection block.

(g) Silvered contact bus disconnect auxiliary switches shall be provided, specifically designed and approved for switching CT circuits with the respective circuits alive (On load changeover) or appropriately supervised disconnect position relays for CT selection. The switches or relays being set so that the auxiliary switch closes prior to main disconnect contacts pre-arcing on closing, and similarly opens after contact arcing ceases on opening. When both bus disconnects are open the CTs disconnected from the bus wires must be shorted and earthed.

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(h) The Contractor shall clearly specify the number of secondary circuits which must be switched, the duty of the switches and the timing between individual switches; the Contractor shall be responsible for selecting switches which are adequate for the intended duty.

(i) For multi-section busbars, one check zone per double busbar section shall be provided.

9.4.13 132 kV Bus Section and Bus Couplers Three-pole phase and one residually connected (earth fault) IDMT overcurrent relays shall be provided on each bus section and bus coupler breaker, each with separately connected instantaneous elements.

A distance relay in line with that specified for feeder protection shall be provided for emergency purposes.

9.5 General Protection Requirements

9.5.1 Protection Relay Power Supplies All protective relay operating supplies shall be provided such that power for operation is either self-derived from the CT or VT circuit or obtained from the relevant 110V DC protection supply. These relay operating supplies to be suitable for successful non-delayed tripping when closing or reclosing onto all faults. The use of small rechargeable cells within the relay unit or system is not acceptable unless the charge cycle and duty can give a maintenance free life of over five years, and the Tenderer shall draw attention to any such proposal.

Supply all equipment (electromechanical or static) suitably barriered and protected so that any surges on the CT, VT or 110V DC supply system does not cause damage or relay malfunction, according to the relevant IEC Standard and the relay manufacturer prescription.

9.5.2 General Protection Testing & Maintenance Facilities Test facilities shall be provided on each relay or relay group to:

(a) isolate and short circuit, on the CT side, the associated CT circuits,

(b) allow insertion of a test device to break into each CT circuit in turn,

(c) isolate voltage supplies, if used,

(d) isolate all trip outputs,

(e) attach portable test equipment to secondary inject the relay group.

These test facilities may be part of the withdrawal facilities for withdrawal relays or separate for non-withdrawable or complex systems.

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Because of the nature of the CT and trip circuit interconnections within each diameter of a 1-1/2 switch station the following additional facilities are required at 400 kV:

- Provide separate test blocks to isolate and short circuit, on the CT side, individual circuit breaker CTs where two or more sets feed into one protective scheme.

- Provide separate multi-element protection isolation changeover switches for each group in the protection of any one plant item, the other group to be kept in service. Provide switches to interrupt all interfaces with tripping, auto-reclose and protection signalling systems.

- Provide similar multi-element isolation switches, one for each protection signalling system (leased or PLC) on each circuit, to isolate all facilities on the 110 Volt side of the interface equipment.

- Provide, within the protection signalling equipment, sufficient isolation and test facilities to test each channel and signal.

9.5.3 Fault Recording and Data Logging Facilities shall be provided to measure and record for each 400 kV line circuit individually and for each 132 kV section, a general record for the following:

(a) Fault duration,

(b) Identity of faulted phase (in case of 400 kV lines and connected plant),

(c) magnitude of voltage variation fault,

(d) magnitude of the phase and neutral currents for 400 kV lines and for 132 kV lines and transformers within the affected station,

(e) operational times for all main 400 kV trip outputs,

(f) phase on which single-pole reclose equipment operated (e.g. signal from the distance protection starting),

(g) main stages within the single-pole reclose cycle,

(h) monitor the protection signalling signals,

(j) at least 500 ms of prefault recording of the voltage and current signals.

Resolution of events should be better than 5ms.

Time and date (month, day, hour, minute) shall be automatically recorded.

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The storing, recording and presenting of operational data as it occurs shall not be over-written by further fault-trips or reclosure that are within the design operating cycles of the current breakers and primary relaying. The final allocation of monitor points is to be approved by the Engineer, agreed based on the type of recorder offered. For each 132 kV section, the monitor it is only required to monitor items I (a)-(d) and (i). If a multiple recorder is used for 400 kV circuits, items I (a)-(d) and (i) must be available on a common recorder initiated by rate of change of voltage starting. Individual or group recorders should be started by the trip of any directly associated circuit.

9.5.4 400 kV Fault Location Facilities shall be provided to monitor currents and voltages available at a line terminal during a fault and such equipment as necessary to compute and record line fault location.

Equipment shall be so designed as to protect the stored data from erasure caused by high speed reclosure onto a persistent fault.

9.6 Relay Panel Arrangement

Relay panel layouts shall be divided with regard to function and DC power supply so that the two DC supplies do not appear on the same panel except as specifically approved.

Panels shall be arranged so that protection circuit isolating, fusing and relay equipment is accessible from the front of the panel. Power supply fuses or switches and isolation devices to be accessible with the panel door closed.

9.7 Direct Transfer Tripping and Teleprotection Signals

The Tenderer shall identify the communications requirements for the protection during his specific site surveys and in discussion with the Employer’s representative. The contract includes the complete provision of communications equipment, including the substation end of the telecommunications link, and the relevant interconnections, whatever the medium used.

400 kV overhead line circuits shall be provided with direct transfer tripping between line feeders ends via two direct transfer tripping channels. Blocking and Permissive Underreach signals shall also be provided for the respective distance protections. Send/receive relays are to be provided for each signalling channel.

A channel shall also be provided for the Directional Comparison Earth Fault protection.

Separate cables are to be used for each teleprotection channel.

At the protection relay panels, the cables for the teleprotection signals are to be terminated on terminals, which are wired directly to isolating links. This is to enable the teleprotection equipment to be readily isolated from the protective relays and the 110 V dc tripping and control supplies. Disconnecting links incorporated in the terminal blocks will not be accepted for this purpose.

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For each discrete teleprotection channel, a two-position test switch ("test/service") is to be installed on the front of the relay panel to enable the functioning of the teleprotection channel to be tested. The switch is to be lockable and provided with a lock and duplicate keys. An indication lamp is to be provided for indicating that the test switch is in the "test" position. A push-button is to be provided to initiate a test signal to the teleprotection equipment. A second indicating lamp shall be provided to indicate that a test signal has been received from the remote station.


10. COMMUNICATION EQUIPMENT


The contract includes the provision of all communication link equipment at the substation for whatever medium is required. This will normally involve Power Line Carrier, but the actual substation communication requirements shall be as set out in the Contract Scope of Work. The generic specification “Standard Specification for Telecommunication and SCADA Systems” shall be used to provide the performance requirements for the equipment. The remote ends of the communications links will be provided by others. Work under this section of the Specifications shall include:

(a) Design of communications equipment terminal ends as part of a total link.

(b) Design, manufacture, delivery to site, installation, testing and guarantee of items of equipment as detailed below.

The Contractor shall co-ordinate all aspects of the work with the suppliers of the remote end communications link equipment to ensure that the complete installation operates correctly and complies in every respect with the communications design specifications.

10.2 Power Line Carrier

10.2.1 400 kV Line Traps (a) Extent of Supply

Provide, deliver to site, and install 400 kV line traps at 400/132 kV substations as part of the overall requirements for Power Line Carrier circuits. The quantities shall be determined by the Tenderer from the Single Line Diagram of Substation Protection available with the solicitation documents. In general, for 400 kV single circuit lines, power line coupling is required on the R and S phases. For double circuit lines on the same towers, the S phase on each circuit will be used. The requirements for lines with mixed configuration etc will be provided in the contract Scope of Work.

(b) General Electrical Characteristics

These shall be in accordance with the general plant requirements of this specification.

(c) General Mechanical Characteristics

The equipment should be of modern lightweight design. All parts should be fully protected against deterioration due to the environmental conditions. If the design of line trap requires them, barriers should be provided to prevent the entry of birds.


(d) Mounting

The line trap should be suitable for pedestal or suspension mounting.

(e) Blocking Impedance

The blocking impedance shall be a minimum of 400 ohms over the required band of frequencies.

(f) Bandwidth Requirements

Precise frequencies have not yet been allocated. The expected bandwidth requirement will be 36 kHz. The geometric mean frequency approximately 100 kHz. Two 4 kHz full duplex power line carrier terminals may be required on each 400 kV line.

(g) Rated Inductance

The inductance of the line trap should be chosen to optimise the design of the coupling equipment with due consideration being given to cost, overall dimensions and the use of standard, proven, designs and inductance values.

(h) Surge Diverters and Protective Devices

Line traps and tuning units shall be provided with suitable surge diverters and protective spark gaps to protect the equipment against transient overvoltages. The power line carrier equipment will be used for protection signalling purposes. The operation of any protective device associated with the line trap should not affect the protection signalling system.

(j) Accessories and Mounting Hardware

The line traps shall be provided complete with all necessary accessories and mounting hardware required for their installation and operation in the overall power and communications systems.

10.2.2 132 kV Line Traps (a) Extent of Supply

Provide, deliver to site, test and install 132 kV line traps at 400/132 kV substations as part of the overall requirements for Power Line Carrier circuits. The quantities shall be determined by the Tenderer from the Single Line Diagram of Substation Protection available with the solicitation documents. In general, for 132 kV single circuit lines, power line coupling is required on the R and S phases. For double circuit lines on the same towers, the S phase on each circuit will be used. The requirements for lines with mixed configuration etc will be provided in the contract Scope of Work.


(b) General Electrical Characteristics


(c) General Mechanical Characteristics

The equipment shall be of modern lightweight design. All parts shall be fully protected against deterioration due to the environmental conditions. If the design of the line trap requires them, barriers should be provided to prevent the entry of birds.

(d) Mounting

The line trap should be suitable for pedestal or suspension mounting.

(e) Blocking Impedance

The blocking impedance shall be a minimum of 800 ohms over the required band of frequencies.

(f) Bandwidth Requirements

The line trap shall be suitable for wide band application in the frequency range 40-500 kHz by fitting the appropriate tuning part.

(g) Rated Inductance

The inductance of the line trap should be chosen to optimise the design of the coupling equipment with due consideration being given to cost, overall dimensions and the use of standard, proven, designs and inductance values.

(h) Surge Diverters and Protective Devices

The line trap and associated tuning units shall be provided with suitable surge diverters and protective spark gaps. The power line carrier equipment will be used for protection signalling purposes. The operation of any protective device associated with the line trap should not affect the protection signalling system.

(j) Accessories and Mounting Hardware

The line trap shall be provided complete with all necessary accessories and mounting hardware required for its installation and operation in the overall power and communications system.

10.2.3 400 kV and 132 kV Line Coupling Capacitors (a) Extent of Supply

In general, power line carrier will be coupled using the primary system capacitor voltage transformers, covered elsewhere in this specification. Where required by the Contract Scope of Work, the Tenderer shall provide, deliver to site, test and install 400 kV line coupling capacitors


at 400 kV/132 kV substations in Iraq as part of the overall requirements for Power Line Carrier circuits.

(b) Coupling Capacitors

Electrical characteristics of 400 kV and 132 kV systems:


System surge impedance 308 ohms

(c) Capacitance

The value of capacitance shall be decided by the power line carrier system design requirements.

(d) Mechanical Characteristics

The coupling capacitors shall be suitable for reliable operation outdoors under the specified climatic conditions. Drawings shall be provided with the tender documents clearly showing the available methods of mounting, principal dimensions, etc.

(e) Drain Coil, Earth Switch and Tuning Components

A suitable drain coil and earth switch, protected by suitable protective spark gaps shall be provided in the capacitor base housing. Provision shall also be made for mounting tuning components. A heater shall be provided if required by the design. The heater shall be suitable for operation from 200 Volt, 50 Hz, single-phase supplies.

(f) Earthing

An adequate means of earthing shall be provided.

(g) High Voltage Connection

Details of high voltage connections shall be given in the tender documents.

(h) Materials and Manufacturing Standards

The materials used and manufacturing methods employed must conform to the standards laid down for substation equipment.

The minimum creepage distance shall be in accordance with the substation design requirements.


(j) Nameplates

The following minimum information shall appear on the nameplates of all coupling capacitors:

1. Manufacturer's name.

2. Type and form designation.

3. Instruction book number.

4. Operating voltage rating.

5. BIL rating.

6. Capacitance.

7. Weight.

10.3 Power Line Carrier Terminal Equipment, Line Matching Units and Co-axial Cable

The Generic specification “Standard Specification for Telecommunication and SCADA Systems” shall be used to provide the performance requirements for the equipment. The normal communication medium will be Power Line Carrier and this will generally require one set of terminal equipment etc for each primary feeder end, as shown on the Single Line Diagram of Substation Protection available with the solicitation documents. In general, for 400 and 132 kV single circuit lines, power line coupling is required on the R and S phases. For double circuit lines on the same towers, the S phase on each circuit will be used. The requirements for lines with mixed configuration etc will be provided in the contract Scope of Work. Any other site specific requirements will be set out in the Contract Scope of Work.

10.4 Protection Signalling Equipment

The Generic specification “Standard Specification for Telecommunication and SCADA Systems” shall be used to provide the performance requirements for the equipment. Protection Signalling Equipment will be required on most Primary System Feeders and the quantities shall be determined by the Tenderer from the Single Line Diagram of Substation Protection available with the solicitation documents.

10.5 Microwave Radio Link Equipment

The Generic specification “Standard Specification for Telecommunication and SCADA Systems” shall be used to provide the performance requirements for the equipment The quantities and configuration shall be as set out in the Contract Scope of Works.


10.6 Telephone Equipment (PABX)

The Generic specification “Standard Specification for Telecommunication and SCADA Systems” shall be used to provide the performance requirements for the equipment. A PABX will be required at each substation and the quantities and configuration shall be as set out in the Contract Scope of Work. The Contractor shall ensure that the PABX is compatible with the Control Centre telephone exchanges, and the existing substation PABX’s that it will interface to. In general, a small PABX equipped with trunk lines connected to each off site communications link will be required. Extension sockets with handsets shall be provided in each room or separate substation building. Where large key equipment areas are concerned e.g. relay rooms, GIS switch houses and outdoor high voltage compounds, additional sockets off the same extension shall be provided to cover the area concerned. Outdoor plant areas e.g. main transformers, shall be served with weatherproof outdoor handsets.

10.7 Optical Fibre Based PDH/SDH Equipment

The Generic specification “Standard Specification for Telecommunication and SCADA Systems” shall be used to provide the performance requirements for the equipment. Where this equipment is required, quantities and configuration shall be set out in the Contract Scope of Work.

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11. ELECTRICAL STATION SERVICES


The work to be done under this Section of the Specification consists of the design, manufacture, testing, supply, delivery, installation, commissioning and guarantee of the following equipment:

(a) Main 110volt DC and communications 48volt DC battery systems.

(b) DC distribution switchgear and panels.

(c) AC distribution switchgear and panels.

(d) Standby / Emergency Diesel Generating Set.

(e) Commissioning power supply.

11.2 Main 110 Volt Station Batteries & Equipment

(a) General

The Contractor shall provide a duplicate 2-wire, 110 V DC (nominal voltage) DC supply system, fed from two independent battery banks, each having separate charging systems. Separate main and subsidiary distribution panels and minimal manual/automatic changeover interconnection between systems so that the loss of one battery bank, charger or main distribution board does not jeopardise the second system. Each battery/charger shall be capable of feeding the entire station load continuously for the rated duration of 8 hours.

The DC voltage shall be 110V + 10%. The Contractor shall submit calculations related to the voltage drops, with a list of the maximum and minimum allowable voltages for all the DC devices and relays.

The battery systems shall be referred to as "A" battery and "B" battery and the protective equipment divided between the two battery banks as indicated in the specifications, so as to maximise the reliability of the protective system in the event of failure of one of the battery banks or related equipment.

(b) Batteries

Batteries shall be of nickel-cadmium, pocket or sintered plate, open or semi-sealed design, housed in suitable translucent plastic containers to BS 6290. Each cell shall be provided with a vent cap and/or filler plug and a pressure operated gas release valve.

Sufficient electrolyte reserve shall be provided to give six monthly maintenance periods.

The plates shall be designed and constructed so that the plates are rigidly held so as to avoid distortion and short-circuiting of the plates.

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The battery shall be suitable for float and boost charging and capable of providing the required output throughout the specified ambient conditions.

The battery cells shall be arranged in tiers on suitable racks and spaced so to allow sufficient access for maintenance. The racks shall be of a design to withstand corrosion by battery electrolyte.

All cells shall be consecutively numbered and terminal cells marked to indicate polarity.

Each battery shall be designed to provide sufficient capacity for operation at full load for eight (8) hours in the event of charger failure.

(c) Battery Chargers

The battery chargers shall be a solid-state type, suitable with respect to size and design for the defined operating conditions. The mode of charging shall be by the constant voltage method and the charging voltage shall be variable to compensate for internal losses in the cells and constant loads, etc. Voltage selection shall be such as to avoid overcharging.

Each battery charger shall be suitably sized so as to be capable of charging both batteries at the same time should one of the chargers fail or be out of service for maintenance.

The system shall be designed for the selection of float and equalising voltage levels most appropriate to the system conditions and co-ordinate this with the rating.

Single or more groups of voltage dropping semiconductor diodes shall be inserted between charger/battery and the d.c. bus to keep the load voltage within operating limits during the different charging modes and for all load conditions. If the load voltage drops below a preset value, supervision relays shall initiate to by-pass the semiconductors and vice-versa. The diodes shall have a rating of at least twice the board’s standing load.

Voltage regulation shall be designed to ensure that the voltage is within ± 1 per cent of the output over the load range zero to full load with an output voltage ripple of less than 2 per cent rms.

The charger shall have an incoming supply voltage monitor to detect loss of supply.

(d) DC Main Distribution Panel

The main DC distribution panels shall be connected to the batteries by a 4 breaker automatic change-over system with a manual resetting scheme, interlocked to prevent paralleling of the batteries. A manual interconnection MCB shall be provided for emergency purposes to allow one charger to charge both batteries.

."A" and "B" battery supplies shall be maintained on separate distribution boards. Provision of sub-distribution from these boards by MCBs or HRC fuses to the various load centres.

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Supply each row of panels by two ring circuits from each of the two DC supplies. One for the protection supply and the other for breaker control.

Protect each protective system and circuit breaker control system with either an MCB or HRC fuse. Provide one DC under-voltage check relay per ring circuit.

The Contractor shall submit a plan that proves selectivity of the fuses and/or circuit breakers.

(e) DC Bus and Battery Instrumentation and Alarms

Provide DC ammeter and voltmeter accurate to within 2 per cent, for each battery, charger and DC Distribution board.

The battery will be high resistance earthed from the mid-point of a potentiometer. MCBs/fuses will be on the positive side of the battery.

Provide earth leakage alarm when any leakage to earth exceeds 2 mA. The detection level of this alarm should be adjustable.

No relay connected to the system should operate due to discharge current of the capacitance of the negative side wiring if an earth fault occurs on the positive side of the relay coil, without any other operation.

Provide DC high voltage and low voltage alarms that give a signal when exceeding the set levels. All alarms to have independent contacts suitable for the alarm equipment and be independent of the 110 volt supply for operation.

(f) Separation of Protection Relay Groups

Provide the following relays groups on the "A" battery:

(i) All protections Group "A".

(ii) All breaker controls, including closing coils and "A" trip coils.

(iii) Alarms, interposing relays etc.

Provide the following protection equipment on the "B" battery:

(i) All of protection group "B".

(ii) Breaker "B" trip coils.

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11.3 Communication 48 V Batteries and Equipment

(a) General

The Contractor shall provide a duplicate 2-wire, 48 V DC (nominal voltage) DC supply system, fed from two independent battery banks, each having separate charging systems. Separate main and subsidiary distribution panels and minimal manual/automatic changeover interconnection between systems so that the loss of one battery bank, charger or main distribution board does not jeopardise the second system. Each supply shall be capable of feeding the entire station load continuously for the rated duration of 8 hours.

(b) Batteries

(i) Battery Voltage:

The battery voltage shall be 48 volts nominal with a 48V ± 10% maximum in operation. The Contractor shall submit calculations about the voltage drops and provide a list of the maximum and minimum allowable voltage on all the 48V DC devices and relays.

(ii) Batteries

The Contractor shall provide a design suitable for communications equipment use.

Provide batteries of nickel-cadmium of the pocket or sintered plate, open or semi-sealed design housed in suitable translucent plastic containers to BS 6290. Each cell shall be provided with a vent cap and/or filler plug and a pressure operated gas release valve.

Sufficient electrolyte reserve shall be provided to give six monthly maintenance periods.

The plates shall be designed and constructed so that the plates are rigidly held so as to avoid distortion and short-circuiting of the plates.

The battery shall be suitable for float and boost charging and capable of providing the required output throughout the specified ambient conditions.

The battery cells shall be arranged in tiers on suitable racks and spaced so to allow sufficient access for maintenance. The racks shall be of a design to withstand corrosion by battery electrolyte.

All cells shall be consecutively numbered and terminal cells marked to indicate polarity.

Each battery shall be designed to provide sufficient capacity for operation at full load for eight (8) hours in the event of charger failure.

Reference shall be made to the general section of the specification for information on environmental and climatic conditions.

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The main battery and charger fuses shall be mounted as close to the battery terminals as possible. Battery and charger cables shall be separately fused and linked.

(c) Battery Chargers

The Contractor shall provide for each battery bank a solid-state battery charger, suitable with respect to size and design for the defined operating conditions. The mode of charging shall be by the constant voltage method and the charging voltage shall be variable to compensate for internal losses in the cells and constant loads, etc. Voltage selection shall be such as to avoid overcharging.

Each battery charger shall be suitably sized so as to be capable of charging both batteries at the same time should one of the chargers fail or be out of service for maintenance.

The system shall be designed for the selection of float and equalising voltage levels most appropriate to the system conditions and co-ordinate this with the rating.

Single or more groups of voltage dropping semiconductor diodes shall be inserted between charger/battery and the d.c. bus to keep the load voltage within operating limits during the different charging modes and for all load conditions. If the load voltage drops below a preset value, supervision relays shall initiate to by-pass the semiconductors and vice-versa. The diodes shall have a rating of at least twice the board’s standing load.

Voltage regulation shall be designed to ensure that the voltage is within ± 1 per cent of the output over the load range zero to full load with an output voltage ripple of less than 2 per cent rms.

The charger output shall be sufficient to return the battery to full charge in twelve hours, after an eight-hour discharge at full load, while maintaining normal service.

The equalising and float voltage levels shall be adjustable and suitable for the range of operating conditions recommended by the battery manufacturer.

The output voltage shall be maintained within ± 1 per cent of its set value for combined input and load variations of:

Load 0 - 100%

Nominal line voltage ± 10%

Frequency ± 2Hz

The regulation response time shall be better than 50 milliseconds.

A suitable DC ammeter and a DC voltmeter shall be provided for each battery, charger and DC main output.

11-6


An under-voltage alarm shall be provided at the charger or its associated distribution board. A contact shall be provided to extend the alarm to an external annunciator.

The charger shall have an incoming supply voltage monitor to detect loss of supply.

(d) DC Distribution Panels

Suitably designed DC distribution panels shall be connected to each battery by a 4 breaker automatic change-over system with a manual resetting scheme, interlocked to prevent paralleling of the batteries. A manual interconnection MCB shall be provided for emergency purposes to allow one charger to charge both batteries.

The distribution boards shall serve as the main distribution points to the communications equipment cubicles and racks.

(i) Design Features:

The distribution board shall have as a minimum requirement:

- MCBs or fuses and links for up to twelve sub-circuits.

- Provision for the fitting of a second group of MCBs or fuses and links for twelve additional sub-circuits.

- DC ammeter and voltmeter accurate to within 2 per cent, for each battery, charger and DC Distribution Board.

- Earth link for earthing one side of the battery, if required.

- DC high voltage and low voltage alarms that give a signal when exceeding the set levels. All alarms to have independent contacts suitable for the alarm equipment and be independent of the 48 volt supply for operation.

(ii) Cabling:

Suitable arrangements shall be made for the glanding and termination of all cables entering and leaving the distribution panel in a manner that allows easy addition of future cables as required.

All distribution cabling shall be radial. All fuses and links shall be fed from suitable low impedance busbars that shall in turn be connected to the battery terminals via the main battery cable.

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11.4 LVAC Distribution Switchgear Panels, Cabling and Socket Outlets

A 380/220 volt, 3 phase 4 wire, earthed neutral system shall be provided for the AC station services. The supplies will be taken from the station service transformers via load breaking, fault making disconnect switches. Each supply shall be capable of carrying the full rating of the transformer.

Arrangement and connection details of the AC systems for both substations are as shown in the Tender drawings.

(a) Main Switchgear

Each of the Station Supplies Switchgear Panels 1 and 2 shall be equipped with an Essential and Non Essential section, with an interconnecting tie breaker. Both the Essential and Non Essential sections are to be fed from the two auxiliary transformers. One of the Essential Boards shall be equipped for possible connection of a single off site supply.

The Essential/Non Essential tie - breaker shall run normally open and be interlocked with the incoming breakers to automatically close when one of the supplies is lost. The switchboard diesel generator breaker will be interlocked to automatically close when both supplies are lost and the diesel is running. The diesel generator starting shall be delayed to allow for any auto reclosing of the HV System so as to prevent unnecessary operation of the diesel generator. Suitable facilities shall be provided to limit the essential loads to meet the requirements specified in the Diesel Generator section of this specification. Manual control shall be provided for maintenance requirements and restoring equipment to normal operating mode.

The main switchgear assembly is to be a single busbar, 380 volt, ac board, metalclad Form 4 type, and is to be termite and vermin proof (IP 50).

The switchboards shall be built up of circuit-breaker units, isolators, contactors, moulded case and miniature circuit-breakers. All units, when built up into a complete switchboard, shall be such that the completed switchboard is of flush fronted design having a neat and clean appearance and is readily extensible.

The units are to house all protection equipment, include lighting, heating and socket outlets as required. Heavy-duty filters, replaceable without tools, shall be provided if forced ventilation system is used.

All necessary mcb’s required to supply all the substation switchgear, transformers, d.c batteries and chargers, and the building services, including air conditioning, lighting and power circuits shall be provided. Sub-distribution from these assemblies shall be from mcb’s to distribution panels. Units are to be supplied with suitable locks and keys.

11-8


(b) Distribution Panels

Distribution panels as required are to be 380 V AC, three-phase and neutral fitted with miniature circuit breakers or equivalent. Type and manufacturer of equipment is to be approved by the Engineer. Panels are to be supplied with locks and keys. Each building is to have its own distribution panel(s) for building services requirements (internal lighting, external lighting, small power, air conditioning, separately). Common loads (i.e non distributed) requiring secure supplies will have feeds from each Station Supplies Switchgear Panel (Essential or Non Essential, as appropriate). The two supplies will be manually selected and have mechanical interlocking to prevent paralleling of the supplies. This will apply to the Control/Relay Building and Diesel Generator Building supply distribution boards.

Contractor is to size the panels and the number required to meet the requirements as detailed in the Plant and Civil specifications.

(c) Power and Convenience Outlets

In addition to those provided under Building Services, the following outlets shall be provided, complete with plugs and sockets:-

(i) Power outlets for portable welding equipment shall conform with BS EN 60309. These units are to be 380 volts, 63 amps, 4-wire (3 phase, neutral and earth), metal-clad to IP 65, weatherproof and incorporate spring-return flap cover. No aluminium is to be used in their construction. They shall incorporate an on-load disconnector, MCB rated to suit the switch and a residual current circuit device rated at 30 mA.

Power outlets are to be supplied on the following basis:

1 - per two Switch and a Half Diameters in 400 kV GIS switch rooms

1 - for each transformer/reactor bank

2 - two for the 132 kV switchroom

1 – workshop

ii) Convenience outlets are to conform to the relevant BS standards Outlets are to be 220 volt, 13 amp AC (2-pole and earth).

Convenience outlets are to be supplied on the following basis:

1 - each breaker marshalling cubicle/Bay Control Unit

1 - each transformer marshalling kiosk

1 - each line termination gantry

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1 - each 380/220V station service main switchboard

1 - each reactor marshalling kiosk

2 - control desk

1 - each row of control metering panels

1 - each row relay panels

(iii) Outlets with capacity of 20A AC and with voltage of 110V/63V, four wires and earth complete with supply transformer shall be provided on each row of relay panels,

(iv) Oil filtration Plant Socket Outlets

One plug and socket outlet shall be provided on the wall adjacent to each transformer bank, and for each line reactor and tertiary reactor bank. The outlet shall be suitably rated for the oil treatment plant, but not less than 150A. The plug and socket shall be of 5 pole type (3ph + E + N) of the metal-clad type complete with a switch-fuse unit, IP 65 rated, for outdoor use and incorporating a spring return flap cover over the plug socket. A sunshade should be provided over the box.

The plug and socket shall be interlocked such as that the socket cannot be switched on until the matching plug is fully inserted, nor can the plug be withdrawn with the switch closed.

The socket unit shall be provided with the following:

• Facility for incoming supply cable looping, and

• Provision for padlocking the switch in the off position.

11.5 Diesel Generator

The diesel generator shall comprise but not be limited to the following items:

Diesel engine with governor and accessories; synchronous generator, 380 volt, 50 Hz, 3-phase 4-wire, high resistance earthed, exciter and voltage regulator;

Fuel tank, complete with stand, fuel line isolating valves, fire cut-off valve, drain valve and sloping tank base to remove water collected in fuel, level gauge, ladder for access to top of tank for fuel delivery/inspection, fuel delivery facilities etc;

Fuel tank bund, complete with oil drainage and water separation facilities, to cater for the volume of the fuel tank plus 10% rain water;

11-10


Mounting hardware, including anti-vibration facilities;

Control panel, including anti-vibration facilities;

Battery/Charger unit shall provide supply for control and engine starting. The battery shall be an alkaline type and complete with automatic battery charger.

Generator circuit breaker and associated generator electrical protection;

Exhaust system, complete with silencer and anti-vibration coupling;

Radiators, with anti-vibration facilities;

Tools, sufficient for routine maintenance;

Two sets of “Start-up” spares

Interconnecting wiring of engine controls;

One (1) suitable walk-in housing for all components, excepting fuel tank, and complete with necessary foundations.

(a) Service Conditions

(i) The fuel tank shall be installed at a safe and convenient adjacent location. The tank shall contain sufficient fuel for three days continuous operation. The ambient air temperature may range from 5°c to 50°c.

(ii) The engine may be required to run for extended periods of time during maintenance, without benefit of its assigned generator loads.

(iii) Equipment will be exposed to wind-borne sand and dust, and therefore shall be equipped with appropriate fuel, oil and air filters.

(iv) Site altitude and air humidity shall be considered by the Contractor to ensure correct cooling system design.

(v) The M-G set will not be used for parallel operation with the mains supply or other generators.

(vi) Although the M-G set is intended for stand-by / emergency duty, all ratings must be based on full load 24 hour continuous service, without benefit of interruption or load cycling, in order to allow for power outage of indefinite duration.

(vii) If the engine has minimum running period/minimum load requirements, the Contractor shall state these and make allowance for them in the automatic control regime.

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(viii) If the diesel generator has load step change limitations, provision shall be made in the essential load control regime to cater for this.

(ix) The diesel generator shall be capable of Black Start i.e able to start and connect to the essential load without any other site resource being available e.g. other battery supplies etc.

(b) Starting System

The engine shall be started automatically on failure of normal power supply.

The generator will be connected automatically to the load and it shall be incorporated into the LVAC system auto-changeover scheme. On restoration of normal supply the diesel shall be unloaded manually.

(c) Engine Instruments

A panel on the engine shall contain:

Tachometer with hour-meter

Lubricating oil pressure gauge

Lubricating oil temperature gauge

Jacket water temperature gauge (if water-cooled)

(d) Engine Protection

The engine shall be equipped with switches and local alarms for shut-down due to operation of the mechanical overspeed governor.

Shut-down, followed by alarm in event of high jacket water temperature or low lubricating oil pressure.

A mechanical lubricating trip shall operate in the event that the engine fails to shut down on low oil pressure due to an electrical malfunction. The electrical controls shall stop the engine through a "fail safe", de-energised to shut down, 24V solenoid on the governor.

(e) Diesel Generator and Control Panel

The Contractor shall size the generator for each substation to suit the sum (plus 25%) of the maximum individual demand kVA of each of the following loads:

- Battery chargers

- At least 50% of the Control/Relay Building split unit air conditioning units

11-12


- Control/Relay Building internal lighting

- Lighting and small power in the Diesel house

- Approximately one third of the substation outdoor lighting

Transformer tap changers

The generator shall be a synchronous type alternator, brushless, direct driven with revolving field. Anti-condensation heating shall be included for the stator winding for connection to a 220 V 50 hertz supply.

A relay assembly shall be mounted in the control panel to provide dry alarm contacts for remote indication of engine safety device operation.

(f) Radio-Frequency Suppression

RFI suppression by means of adequate shielding and filtering shall be included to minimise radio interference in standard broadcast bands.

(g) Site Testing

The Contractor shall propose and perform sufficient tests to satisfy the Engineer that the engine generator and all auxiliaries are in satisfactory working order.

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12. CABLES

12.1 General

All cables provided under this Contract shall be of type and finish approved by the Engineer and shall be provided with a termite and vermin resistant covering. Many instances of rats eating away the outer PVC insulation cover are reported therefore, a suitable non-corrosive wire armour to make the cable vermin-proof shall be provided for all LV auxiliary and control and protection cables.

Wherever any part of an LV cable circuit is installed within a room or enclosure containing electrical control or protection equipment, in the proximity of oil filled equipment or where personnel are normally present cables employing insulation and sheathing which minimises the production of smoke and toxic fumes to IEC 60331 and/or 60332 shall be used. Cable installed wholly outdoors may be of a PVC insulated type.

Where cables pass through holes in floors immediately beneath oil filled switchgear or other oil filled equipment, the Contractor shall be responsible for plugging the holes with approved silicon foam fire seals or other approved materials after the cables have been installed and the cost thereof is deemed to be included in the contract price quoted for the cables.

Cables for power supplies at voltages up to 600/1000 V and for all 220 V ac and dc protection, control, alarm and indication shall have copper conductor with XLPE or PVC insulation and overall oversheath, together with galvanized steel wire armour. They shall comply with IEC 60227 and IEC 60228 and the colours for PVC insulation shall comply with IEC 60304.

Cables for circuits between 250 and 600V shall be 1,100 V grade. All other voltage levels shall be approved by the Engineer. Control, Protection and indication cables shall be installed with a minimum of 15 per cent (15%) spare conductors.

The conductors shall be plain annealed copper wire complying with IEC 60228 (BS 6360) as applicable or equivalent and all cores shall be clearly identified by printed numbers at regular intervals.

The minimum conductor size shall be not less than seven strands of 0.67 mm diameter wire, or in the case of single wire conductors the minimum cross-sectional area shall be not less than 2.5 mm2. In special cases for light current Control installations single strand, annealed copper conductors with a cross-section of 1.5 mm2 may be used.

All sheaths shall be free from defects and impervious to water.

Multicore and control cables shall be terminated in accordance with the manufacturers recommendations and the cable cores shall be left long enough to be terminated without the addition of separate tails.

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The Contractor is responsible for checking all cable routes for burden on CTs and VTs for voltage drop on DC control and trip circuits and for satisfactory service with the equipment supplied. It is also the Contractor's responsibility to route cable to minimise "pick-up" within the station and where necessary to take precautions to prevent damage to cable sheaths from system earth fault current.

The Contractor shall submit full details of all loadings on cables and in the case of interposing current transformer connections, the loop resistance of each circuit.

The Contractor shall provide fully detailed wiring diagrams covering all parts of the plant. Detail diagrams shall be cross referenced and shall show multicore cable schedule reference numbers to facilitate cable identification.

12.2 Power Cables

The power cables covered by this section are to be thermally independent circuits laid in trenches and ducts generally as shown in the layout drawings as follows:

- 132 kV single core cables from SF6 switchgear to overhead lines

- 11 kV single core cables from 11 kV from the auto transformer to the 11 kV switchgear.

The installed cable system shall be designed for a reliable service life of at least 40 years.

All cables, joints, terminations and ancillary equipment will be fully type tested in accordance with the most current BS, IEC specifications and the latest recommendations from CIGRE.

Continuous rating calculations are to be performed in accordance with IEC 60287.

Short circuit ratings must be calculated using the adiabatic methods described in IEC 60949.

Cyclic and emergency ratings should be calculated in accordance with IEC 60853.

The Contractor is required to provide calculations to demonstrate that the cables meet the required cable cyclic loadings as specified for the Transformers at the site conditions.

132 kV cables and accessories shall, as a minimum, meet all the requirements of IEC standard 60840 plus any additional requirements specified within this specification.

The 132 kV single core cables shall comprise a water-blocked circular stranded conductor, insulated by a continuous vulcanisation triple extrusion process simultaneously applying a thermosetting semi-conducting conductor screen, a thermosetting XLPE insulating dielectric and a thermosetting semi-conducting core screen. All three materials should be extruded in one operation and fully bonded. The extruded core shall be cured using a dry curing process and the byproducts of cross-linking removed prior to the application of the metallic sheath. The core shall be sheathed overall with an extruded seamless lead sheath, if deemed necessary by the cable supplier, copper wires may be included to

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augment the short circuit carrying capacity of the metallic sheath. The cable shall be longitudinally water-blocked under the lead sheath. The oversheath shall be continuously extruded MDPE or HDPE and have anti-termite additive and shall be coloured BLACK. A thin layer of graphite or other conductive layer shall be applied overall to permit testing of the cable oversheath.

The oversheath should be legibly embossed along its length with the following information:

132000 V Electric Cable, (Manufacturer), (Year of Manufacture) MOE as appropriate to the rating.

The embossed letters and figures shall be raised and consist of upright block characters along two or more lines, approximately equally spaced around the circumference of the cable. The maximum size of the characters shall be 13 mm and the minimum size not less than 15 per cent of the nominal or specified external diameter of the cable or 3 mm, whichever is the greater. The spacing between the end of one set of embossed characters and the beginning of the next on the legend shall not exceed 150 mm. Any additional information embossed on the sheath (e.g. the Manufacturer’s name) shall not affect the spacing between repetitions of the legend.

Both ends of the cable shall be rendered fully watertight by fitting a metallic end cap and a pulling eye that are plumbed to the cable metallic sheath. The pulling eye shall be directly connected to the conductor and be capable of withstanding a tensile load of 100 N/mm² of conductor area up to a maximum of 6 tonnes. When requested by the user, pulling eyes shall be fitted to both ends of the cable.

The cable shall be despatched on a drum of suitable construction of minimum hub diameter 20D (where D is the overall diameter of the cable). The drum shall be fully enclosed by either adjacent fitting wooden battens or continuous metallic cladding.

Gas Immersed cable terminations into 132 kV SF6 switchgear shall comply with the requirements of the latest version of IEC 60859. The Supplier shall demonstrate that terminations meet the mechanical loading of IEC 60859. The terminations may be of "dry type" or “wet type” construction, containing an epoxy resin insulator and an elastomeric stress cone. The insulator shall be constructed with a ‘blind end’, i.e. in such a way that the final seal between the cable insulation and the SF6 is made and tested at the factory and not at site, ideally this will take the form of an un-perforated metallic electrode cast into the epoxy resin insulator. The cable glands of the sealing ends shall be insulated from the SF6 switchgear.

Outdoor Termination insulators must be manufactured from Porcelain materials, all materials shall be fully factory tested during production. The pollution severity shall be ‘very heavy’ as defined in IEC 60815. Corona shields and arcing rings or horns shall be provided at the top of each open type termination and a horn or ring at the base. The base itself shall be insulated from supporting steelwork by mounting upon porcelain pedestal type insulators.

Cable joints may be of the one-piece premoulded type or prefabricated type. Taped joints are not acceptable. The joint shall be provided with a copper joint shell suitable for a metallic seal to the extruded metallic sheath of the cable. Cable joints buried in the ground shall be enclosed in a fibreglass or equivalent casing and the space between the joint and casing shall be completely filled with a bituminous or thermosetting resin compound. Bitumen filled boxes shall not be used for cable

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joints installed in tunnels; such joints may be wrapped in a suitable insulating tape or heat shrink layer.

The 132 kV cable circuits shall be installed as insulated sheath systems. Single point or cross bonding may be employed to reduce sheath losses. In such systems, sheaths of different phases shall be bonded together only at the positions where they are earthed. The design of all specially bonded systems shall be such as to ensure that there is a continuous metallic return path of adequate cross-section for the specified fault current. All required direct inter-sheath and sheath-to-earth connections shall be made via disconnecting links enclosed in link boxes. Inter-sheath and sheath-to-earth connections through sheath voltage limiters shall be disconnectable within link boxes. Designs of bonding leads and link boxes shall be submitted to the Engineer for approval prior to installation. For system design purposes, the magnitude of sheath voltages induced under balanced maximum full load conditions and also under prospective short-circuit fault conditions shall be calculated by the methods and formulae recommended by CIGRE. Details of all such calculations shall be submitted to the Engineer for approval. At terminations, the base metal work of the cable sealing end shall be shrouded against accidental contact if the sheath voltage exceeds 10V. In order to minimise transient over-voltages on sheath insulation, sheath voltage limiters (SVLs) shall be installed at unearthed ends of single point bonded sections. Under certain circumstances, SVLs may be necessary at earthed terminations into SF6 switchgear. SVLs shall be of zinc oxide type and shall consist of three non-linear resistors housed in the link box, the star point being earthed normally to local earth points. SVLs installed at metalclad terminations shall be encapsulated. The SVLs shall be capable of withstanding the voltages and currents impressed upon them and of limiting transient voltages to acceptable levels. Designs of SVLs shall be submitted to the Engineer for approval prior to installation.

All links and SVLs, other than those directly connected across sectionalising insulation at metalclad equipment terminations shall be enclosed in stainless steel or cast iron boxes that shall be earthed. SVLs and associated links shall be accommodated in a common housing unless otherwise approved by the Engineer. The boxes shall be provided with a means of preventing incorrect link positioning and shall also be provided with a label showing the normal link arrangement. The terminal posts and links shall be suitable for the specified short circuit requirements. The link housing shall be designed to confine the effects of the failure of SVLs and link insulation to withstand the duty imposed upon them by an internal cable fault due to the high system fault levels. All link boxes shall be of horizontal type with bolted-on lids suitable for installation in shallow pits below ground surface unless otherwise agreed by the Engineer. Pits shall be provided with removable cast iron covers.

The link box shall have a label fitted externally bearing the legend:

DANGER - ELECTRICITY

The label shall also give circuit identification details. Appropriate warning labels shall also be affixed inside the box. A phase identification label shall be provided adjacent to each terminal.

Bonding leads shall have PVC or polyethylene insulated stranded plain copper conductors and shall be of concentric construction. The type of PVC or polythene used shall be suitable for a short-circuit temperature of 160ºC.

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Bonding leads shall comply with BS 6346 as far as applicable.

The outer insulation of the bonding lead shall be embossed with the legend:

ELECTRIC CABLE-BONDING LEAD

Joints in bonding leads are not acceptable in new installations, but may be used in subsequent alterations e.g. diversions, subject to the approval of the Engineer. All connecting leads shall be as short as possible and of the concentric type. Except for connections to the SVLs at unearthed sheath positions, bonding and earthing leads shall be of sufficient cross section to meet the prospective system fault and transient duties.

11 kV cables shall, as a minimum, meet all the requirements of IEC standard IEC 60502-2 and BS 6622. Cables laid within buildings shall have a low emission of smoke and corrosive gasses and shall also meet the Flame Propagation, smoke emission and corrosive and acid gas test requirements of BS7835.

11 kV accessories shall, as a minimum, meet all the requirements of the latest editions of IEC standard IEC 60502-4 and BS 7888.

The 11 kV single core cables shall comprise circular stranded copper conductor, insulated by a continuous vulcanisation triple extrusion process simultaneously applying a thermosetting semi-conducting conductor screen, a thermosetting XLPE insulating dielectric and a strippable thermosetting semi-conducting core screen. All three materials should be extruded in one operation. The core shall be copper tape screened with aluminium wire armour. The oversheath shall be continuously extruded and contain anti-termite additive, 11 kV cables shall be coloured RED.

Where single point bonding of 11 kV cable is required to meet the current rating requirement the cables shall be bonded at the switchgear end of each circuit.

12.3 Multicore Cables

Multicore cables shall of stranded copper conductor with cross section of conductor not less than 2.5 square millimetres. Each core shall be numbered individually and uniquely.

12.4 Cable Terminations

Cable terminations shall provide reliable and rigid connection and shall be non-self loosening type of design approved by the Engineer.

Modern cable core terminals shall be used for stranded copper conductors, of a design approved by the Engineer.

Where crimp type terminals are used, adequate procedures shall be in place to manage the crimping tool to ensure consistency of the crimp.

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12.5 Identification of Auxiliary Cables

All auxiliary cables shall be identified at both ends by bands on which shall be engraved the cable number, the number and size of cores, the type of cable and the destination. The bands shall be made of material proofed against corrosion, damp and mechanical wear.

The cable installation; laying, entering to a box or panel and termination shall be made to ensure easy identification of all the cable wires, cable numbers and marks for following the wiring.

12.6 Terminal Colouring and Labelling

Phase colours shall be marked in an approved manner on cable boxes, tail ends and single-core cables at all connecting points and/or any positions the Engineer may determine.

12.7 Termination of Auxiliary Cables

Auxiliary cables shall be terminated in a manner approved by the Engineer with clamps or armour clamps as may be required.

Where tails are liable to be in contact with oil or oil vapour, the insulation shall be unaffected by oil and subject to special approval by the Engineer.

12.8 Laying and Installation of Cables

Direct buried cable shall not be accepted. Cables shall be installed in concrete trenches with removable slab covers, or rigid conduits. The routing shall be generally as shown on the drawing.

All cables laid in concrete trenches shall be the armoured water-proof type.

Where cables enter or pass through ducts or trenches, adequate space shall be provided for the later installation of a further 15 per cent (15%) of new cables. Openings to floors and foundation pads shall be large enough to allow free movement of the cable during installation. Trenches and ducts shall be sealed where they enter a building to prevent the entry of moisture, gases and vermin into the building.

Where cables enter a marshalling box, kiosk or panel, cable glands shall be provided.

Manufacturer's restrictions on the bending radius or the cable shall be strictly adhered to and sharp bends which might damage the cable or cause difficulty in pulling shall be avoided.

12.9 Control Cables

All 110 volt DC cabling between outdoor equipment and the Relay Building shall be by multi-conductor cable shielded overall, routed via marshalling kiosks as required. Interconnections between outdoor equipment (interlocks, etc) shall be made at the marshalling kiosks.

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12.10 Metering Cables

Where transducers are required to drive indications, they shall be located in the Relay Building to keep the ac connections as short as possible. AC current and potential cables shall be multi-conductor shielded overall. These cables shall run direct between outdoor equipment and the Relay Building.

12.11 Protection Cables

All AC current and potential cables for protective relaying functions shall run directly from outdoor equipment to the Relay Building. Connections shall be made with multi-conductor cables, shielded overall.

Current and voltage transformer circuits shall have their star point earthed at one point only per metallic circuit. The earth point shall be in the Relay Building, to reduce interference in the connection.

DC power supplies to relay panels shall be shielded overall.

12.12 Earthing

Cable sheaths and armouring will normally be earthed at both ends. Single point earthing shall be provided on specific cable sheaths to reduce induction. The teleprotection and 48 volt control cables shall be designed, in co-ordination with the terminal relays, to be immune to pick up levels associated with earth faults in the station and normal operation of station equipment.

12.13 Communication Cables

Twisted pair cable with overall cable shield shall be used for communication cables. To minimise exposure to interference, the communication cables shall be isolated from power cables wherever practicable.

Twisted pair cable shall conform to BS 7870. Twisted pair cables shall be used for interconnection between protection signalling equipment and protection equipment and shall be suitable for carrying signals without any weakening effect over distances of about 300 metres.

Only armoured cable shall be used in the switchyard.

Cables used for telephony shall be twisted pair and shall not be more than 0.6mm diameter solid copper conductor, suitable for Insulation Displacement Connections (IDC).

Cables entering the substation from outside shall be of paired construction and the entry conduits shall be non-metallic, and non-corrosive.

Coaxial cables where required shall be suitable for installation in cable trenches and shall be suitable for carrying signals without any weakening effect over distances of about 600 metres.

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12.14 SCS Cabling

All cables for SCS transducer measurements are to be multi-conductor twisted pairs, individually screened and shielded overall. Direct input current and voltage shall be via multi conductor Control Cables. All cables for SCS status indications are to be multi-conductor twisted pairs and shielded overall.

The Contractor shall supply and install all necessary cables between substation equipment and the SCS BCU/RTU’s.

12.15 Cable Functions

The Contractor shall provide separate cables for the following functions and for the "A" and "B" systems. Multi-function cables shall not be used.

AC direct CT secondary circuits for metering and protection.

AC direct VT secondary circuits for metering and protection.

DC 110 volt protection control and indication circuits.

DC 48 volt protection signalling interface pilots.

DC 48 volt control and indication circuits.

Transducer output-metering information circuits.

AC 380/220 volt main service cables.

Supervisory control circuits.

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13. SUBSTATION EARTHING SYSTEMS

13.1 Earthing System Design

The earthing system shall be designed to meet the requirements of this specification and shall be in accordance with "The Guide for Safety in Alternating Current Substation Grounding" as published by the Institute of Electrical and Electronic Engineers Incorporated, Publication No. IEEE 80. The Contractor shall present calculations to show the earthing system meets these requirements and can be shown to be safe in terms of touch, step and transferred potentials.

The design of the earthing for the 400 kV, 132 kV, 33 kV and 11 kV systems shall each be considered independently. Each system shall be adequately bonded together during normal system operation.

Electrical measurements of the subsoil at various depths, up to 20 metres shall be made at the Site of each substation in order to determine the layered effects of the ground from which the effective ground resistivity and hence the expected resistance of the proposed earth grid system may be predicted.

Soil composition may be highly corrosive and special consideration shall be given to this problem. The earthing grid shall be effectively protected against corrosion. Cathodic protection, if considered, may adversely affect other equipment and shall be subject to approval by the Engineer.

In actual design, the earthing system shall take the form of a combination of grids of buried conductors and earth rods driven vertically into the ground. Within the grid, conductors shall be laid in parallel lines at reasonably uniform spacing. They shall be located along rows of structures or equipment to facilitate the making of earth connections, where practical.

The main earth and each subsidiary earth shall have a sectional area, as required by fault currents of not more than 0.5 second duration but in any case not less than 120 mm2 in any part of its length. Each branch connection shall have a sectional area of not less than 70 mm2.

Connections to the grid of all non-current carrying metallic parts, which might become energised by chance, such as metal structures, building earth, equipment, earth rods, water pipes, etc. shall not be less than 70 mm2 and shall be of adequate size, current-carrying capacity and mechanical ruggedness.

The spacing between conductors forming the mesh system shall be such as to limit the grid potential rise to a value that limits the touch voltage to a value not greater than the maximum tolerable touch potential assuming a fault clearance time equal to that of the main protection equipment being provided.

Each group of earth electrodes shall be connected to the main earth grid through connections having a sectional area of not less than 120 mm which shall be protected from corrosion.

The grid shall be subdivided into a number of sections, interconnected with test links. These links shall be accessible from above-ground.

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Areas of grid, where high concentrations of fault currents can appear as at neutral earthing connections, shall have reinforced conductor sizes where necessary, to handle adequately the highest fault current and its duration.

In case the equipment is widely spaced in the station, individual local grids may be established at the various equipment locations and the local grids shall be interconnected and connected to earthing grid. Interconnecting conductors shall not be less than the size of the conductor for main grid.

Metal parts of all equipment, other than those forming part of an electrical circuit shall be connected directly to the main earth system via a single conductor. The arrangement of the mesh earth system shall be such as to minimise the length of these single connections.

Earth bars installed directly into the ground should normally be laid bare and the trench back-filled with fine topsoil. Where the soil is of a hostile nature, precautions must be taken to protect the earth bar.

Copper to copper joints on strip conductor shall be brazed, using zinc-free brazing material with a melting point of not less than 600°C, or by approved exothermic welding.

All exposed joints shall be at a minimum height of 150 mm above floor or ground level.

Earth conductor joints that are required to be broken for testing or maintenance shall have mating surfaces tinned.

The grid voltage rise under fault conditions shall not exceed 15 kV. If the calculated grid voltage rise exceeds 430 V (or 650 V if fault clearance time is less than or equal to 200 ms) the Telephone Authority shall be advised of the grid voltage rise, by the Engineer, and of the distance of the 650 V contour from the substation grid periphery.

The measured earth resistance shall not exceed 0.5 ohm. In the event of a higher value being considered, precaution shall be taken it does not affect the minimum pick-up currents of earth relays. A value higher than 0.5 ohm. shall be subject to the approval of the Engineer.

The resistance shall be measured with all transmission line earth wires connected to the earthing grid.

In the event of the substation resistance obtained with the foregoing installation being of a magnitude unacceptable to the Engineer, then where practicable, the ground area enclosed by the earth system should be increased by installing directly in the ground a copper conductor in the form of a ring around the site at a significant distance from the boundary fence. Alternatively earth conductors can be directly buried radially outside the substation perimeter fence. The use of earth plates as current carrying electrodes is not acceptable.

From the point of view of the possible damage to apparatus, the earthing system shall be such as to limit voltage appearing between the substation equipment and the main body of earth, so that insulation breakdown or burning does not occur on apparatus. For the same reason, voltage rise between earthed points in the substation shall be kept to a minimum. In addition, the effectiveness of any surge protection devices shall be fully realised by providing an adequate earth path. In this case, the earthing system shall not only be of low resistance, but of as low reactance as practicable.

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After installation of the earth system the Contractor shall measure the resistance of the substation. The method used shall preferably be the "fall of potential" method, requiring the availability of a local low voltage supply but other methods using an earth resistance megger will be acceptable in the event of a local supply being unavailable.

13.2 Step and Touch Voltage

The earthing systems shall be so designed as to keep the "step" and "touch" potentials within acceptable limits, thereby ensuring safety to the personnel. The aim shall be to ensure that under both normal or abnormal conditions no dangerous voltages can appear on the equipment and accessories to which a person has legitimate access.

13.3 Equipment Earthing

Circuit breakers, power transformers, voltage transformers, earthing and auxiliary transformers, earthing switches and other electrical apparatus shall each, be connected to the main earth bus by means of a separate subsidiary connection.

Gradient control mats shall be installed adjacent to each circuit breaker and disconnect switch mechanism box. Each mat will be connected directly to the earthing grid and the equipment.

Isolating supports, busbar supports and cable sheaths may be earthed in groups by a separate branch connection from each item of equipment in the group the branch connections being connected by a single subsidiary connection to the main earth. Isolating and earth switch mechanism boxes shall be earthed by a connection separate from that effecting the earthing of the associated switch.

The main members of the steel structures shall be earthed by continuous copper connections bonded to the steelwork and these connections shall be connected separately at each column to the main or subsidiary earth.

Connections to apparatus and structures shall be made clear of ground level, preferably to a vertical face and protected against electrolytic corrosion.

Current transformer and voltage transformer secondary circuits shall be complete in themselves and shall be earthed at one point only (at the Relay Building) through links situated in an accessible position. Each separate circuit shall be earthed through a separate link, suitably labelled. The links shall be of the bolted type, having necessary provision for attaching test leads.

The earth links for protective and instrument current transformer secondary circuits shall be mounted at the Relay Building; earth links for metering current transformer secondary circuits shall be mounted at the Relay Building.

The earth system shall be designed so as to include all overhead line terminal towers, which shall be earthed by extending the system so as to envelope all towers within the earth system. Each tower shall be bonded directly to the earth system from at least two locations. Structures and masts for lighting and security surveillance equipment shall also be within the perimeter of the earth grid. No fixed low voltage equipment, with the exception of a warning or alarm button and intruder alarms, which shall be of the double insulation type, shall be erected outside the perimeter of the earth grid.

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All control and relay panels shall have a continuous earth bus run of sectional area approved by the Engineer along the bottom of the panels, each end being connected to the main earthing system. Metal cases of instruments and metal bases of relays on the panels shall be connected to this bar by conductors of sectional area approved by the Engineer.

Loops shall be provided on the earthing system in positions approved by the Engineer, for the attachment of portable earth connectors during maintenance. These will normally be in the earth bar run between the equipment and the base of the structure. They shall be formed separately from the bar and soldered or thermo-welded thereto. Where necessary, rods shall be provided at the tops of bushings or insulators for the attachment of portable earth clips.

Earthing for high frequency coupling equipment and surge diverters shall be via a copper rod driven directly into the ground at a position immediately adjacent to the equipment being earthed in addition to the normal earth connection.

13.4 Fence and Perimeter Earthing

The fence surrounding the substation shall be earthed to its own earth grid and the fence earth grid shall be connected to the main station earthing grid at frequent intervals as approved by the Engineer.

A continuous conductor shall be laid outside the periphery of the substation site at a distance of 1.5 to 2.0 metres from the boundary fence and at a depth of between 0.6 metres below the surface. This shall be welded to earth rods installed at adequate intervals and at points adjacent to each corner and immediately below any overhead line entering or leaving the Site. The location of the mesh conductors shall be such as to enable all items of equipment to be connected to the earth system via the shortest possible route. All corner fence posts and posts adjacent to earth rods shall be effectively connected to the earth conductor.

Gateposts forming part of the substation fence shall be bonded together with below ground connections and the gates themselves shall be electrically bonded to the posts.

The alternative approach of independently earthing the fence and placing it outside the earth grid area shall only be adopted if the above mentioned procedures prove insufficient or impracticable. The Contractor shall provide calculations to show that this approach produces safe touch voltages at the fence and shall ensure that the fence is isolated from all other buried metalwork.

13.5 GIS Substation Earthing Systems

The earthing system shall comprise a mesh grid formed by copper strip or flexible conductor buried directly in the ground outside the GIS building and arranged so as to utilise fully the available site area. The earthing system inside the GIS building shall be connected to the external system at a minimum of two locations. The reinforced concrete floor slab of the GIS building shall be maintained at earth potential by connecting the reinforcing bars to the earth grid at intervals of 5 m. The reinforcing bar shall be provided with a connection brought out to a vertical face for connection to the main earth bar.

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Where the area of the site is restricted to that of the GIS building it may be necessary to lay an earth mesh formed of copper strip or flexible conductor under the concrete floor slab before building work commences; this shall be determined by calculation and will depend upon the characteristics of the site.

13.6 Earthing of Neutrals

400 kV and 132 kV systems shall be effectively earthed.

400 V ac system shall be solidly earthed.

33 and 11 kV systems shall be earthed through a grounding transformer.

13.7 Surge (Lightning) Arrestors

In the case of surge (lightning) arrestors a local earthing connection shall be made by driving electrodes into the earth near the arrestors and the lightning arrester earthing conductor shall be connected to both the rod and to the common earthing grid of the station. The connection from arrester to earth shall be as short and as straight as possible. The conductor shall not be less than 120 mm 2.

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14. LIGHTNING PROTECTION


The work to be done under this section shall consist of the design, supply, delivery to site, erection, commissioning and guarantee of the lightning protection system for each substation.

The system shall be designed in accordance with the following requirements. However, the Contractor may submit as an alternative, other shielding systems giving equal protection.

14.2 General

For the GIS substation the building shall be designed to provide adequate shielding of the high voltage equipment from direct lightning strikes.

For AIS equipment protection shall be provided to effectively shield the station structures and equipment against direct lightning strikes. Where applicable horizontal skywire conductors supported by the main structures, and lightning masts will be used to shield the AIS equipment.

Downlead conductors connecting the overhead system to earth shall be installed at even intervals with a view to offering low impedance to the passage of stroke current to the earthing grid and shall provide a direct path. No sharp bends or narrow loops in conductors to the earthing grid shall be acceptable.

The downlead conductor system shall be of copper or copper clad steel of low impedance, and durable and highly rugged construction. It shall require no maintenance and both conductor and clamps shall be corrosion-resistant. In particular, allowance shall be made for corrosive atmosphere and salt-laden air where applicable. Steps shall be taken to prevent galvanic corrosion.

Where any part of the downlead conductor system is exposed to mechanical injury it shall be protected by covering it with moulding or tubing, preferably of wood or other non-conductive material. If metal pipe or tubing is used around the conductor the conductor shall be electrically connected to the pipe or tubing at both ends.

Joints in downlead conductors shall be as few in number as practicable. Where they are necessary they shall be thermal-well types, mechanically strong, well made and shall provide adequate electrical conductivity.

14.3 General Design Data of Lightning Shielding System

The substation lightning protection design shall be in accordance with up to date techniques and will follow the general procedure described below:

- The design ISOKERAUNIC level shall be not less than 25 thunder-days per year. This is equivalent to a ground flash density (GFD) of not less than 3.84 strokes per km2 per year.

- The design shielding failure risk shall be not greater than one failure per 100 years.

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14.4 Method of Design of Lightning Shielding System For AIS Equipment

The method shall be based on the use of Fig. 1 and Fig 2 to establish the protected distance and hence the shielding angle given by a skywire. The Contractor shall be responsible for the selection of skywire effective height, which shall be approved by the Engineer.

In making use of Fig. 1, which gives the protected distance for a 30.5 metre length of skywire, the following methods should be used based on IEEE paper T75-060-9.

A = Total area, L x W

n = Number of equal areas A1 totalling A.

Y1 = Shielding failure risk for A1 - nY years.

XP = Protected distance Ey skywire.

H = Effective height of skywire. The difference in height between the lightning conductors and highest equipment.

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Method:

(1) Select A1 to be protected by one lightning conductor 30.5 metre in length.

(2) Determine protected distance XP from XP = A1/.60 metres.

(3) From Y1 and XP obtain effective H from Fig. 1.

(4) Total number of parallel skywires = 30.5 n/L or 30.5 n/W.

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15. INSPECTION AND TESTING

15.1 General

The material shall be subject to inspection and tests by the Engineers representatives at any time during manufacture in order to establish compliance with the specified requirements. All testing and inspection shall be made at the place of manufacture.

The dates for readiness for inspection and testing, access to site(s), delivery and completion of the various sections of the Contract Works shall be stated in the Schedules.

The Employer will provide any on site electrical energy for the purpose of approved preliminary tests and for the official tests. Where applicable, this supply will be metered and charged for.

15.2 Inspection

The manufacturers shall provide all inspection facilities for the said inspection and testing. The inspector shall have the right of rejecting any portion of the material at any time during manufacture if it does not meet with the requirements of this specification in all particulars. The Inspector may oversee the packing and shipping of all materials to be supplied.

Inspection of incoming goods and components, and subassembly testing, shall be undertaken by the Contractor in accordance with the procedures set out in the Contractor's own Quality Plan.

No inspection or lack of inspection or passing by the Engineer of work, plant or materials, whether carried out or supplied by the Contractor or sub-contractor, shall relieve the Contractor from his liability to complete the Contract Works in accordance with the Contract or exonerate him from any of his guarantees.

15.3 Testing

15.3.1 Approach to Testing The Contractor shall carry out the tests stated in accordance with the conditions of this Specification and, without extra charge, such additional tests as may be reasonably required to confirm that the Contract Works comply with this Specification under either test whether in manufacturer's works, on the Site or elsewhere. Type tests may be omitted at the discretion of the Engineer if satisfactory evidence is given of such tests already made on identical equipment.

The principle of testing shall be that, at stages throughout the work, formal tests shall be performed and recorded against written test specifications, to provide a high level of confidence to the Contractor and the Engineer that subsequent stages can proceed.

The degree to which the Engineer intervenes in the process will depend upon the level of confidence built up during the project.

Tests shall be arranged to represent working conditions as closely as possible.

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15.3.2 Responsibilities Not less than 3 weeks notice of all tests shall be given to the Engineer in order that he may be represented if he so desires. Failure of the Contractor to give such notice which results in a delay in the completion of the tests cannot be used by the Contractor as a reason for failure to meet the overall completion date and any extra costs incurred by the Contractor are not recoverable. As many tests as possible shall be arranged together. Two copies of the Contractor's record of tests shall be supplied to the Engineer.

The Contractor's responsibilities shall include but not be limited to requirements to:

(a) Produce written test plans, schedules, procedures, method statements, test record sheets and procedures for fault reporting, for all tests.

All test documentation associated with a subsystem or system test shall be submitted for approval by the Engineer at least 12 weeks prior to the commencement of the associated test.

(b) Ensure that all test documentation associated with any testing has been approved by the Engineer prior to the commencement of the corresponding testing.

(c) Provide the equipment, test equipment, test software, personnel and facilities to conduct the tests.

(d) Successfully carry out all tests according to the approved test procedures and correct any errors, with subsequent re-testing of functions that may be affected by the correction, prior to the witnessed acceptance tests.

(e) Provide facilities for the Engineer to witness any Factory tests.

(f) Produce permanent records of all test progress and results in a formal systematic manner.

(g) Carry out all remedial work and re-testing found to be necessary in order that the equipment should pass the tests.

Each of the above responsibilities shall be discharged to the satisfaction of the Engineer, but approval by the Engineer shall not imply any diminution of the Contractor's responsibilities.

The Contractor shall supply suitable test pieces of all materials as required by the Engineer. If required by the Engineer test specimens shall be prepared for check testing and forwarded at the expense of the Contractor to an independent testing authority selected by the Engineer.

It is expressly the responsibility of the Contractor to satisfy himself that items ‘supplied by others' are in a satisfactory condition for the Contractor's tests to be conducted.

The Contractor shall be responsible for the proper testing of the work completed or plant or materials supplied by a sub-contractor to the same extent as if the work, plant or materials were completed or supplied by the Contractor himself.

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15.3.3 Test Equipment and Facilities The Contractor shall provide all equipment and services required for testing, including, but not limited to:

(a) Laboratory test instruments

(b) Special test equipment, emulators, simulators and test software, to permit full testing of System functions and performance (in particular a means of connecting to or emulating the NCC Master Station)

(c) Other items of the System, specified elsewhere as being part of the Contractor's supply, even if not part of the Subsystem under test

(d) Consumables.

All test instruments shall be subject to routine inspection, testing and calibration by the Contractor. All test instruments shall be subject to approval by the Engineer and, if required by the Engineer, shall be calibrated at the expense of the Contractor by an approved standards laboratory prior to being used during the testing.

15.3.4 Conduct of the Tests The Contractor shall conduct the tests in accordance with the approved test procedures and shall enter the results in the result sheets.

For each test, the Engineer will determine whether the test has passed or failed. In general, the test will be considered to have failed if either:

(a) the result of the test is not in accordance with the expected result described in the test procedure, or

(b) the result of the test is in accordance with the expected result described in the test procedure but some other unexpected or unexplained event occurred which the Engineer considers to be a fault.

Full use shall be made during the tests of operator manuals and other documentation provided by the Contractor to provide a series of tests of their accuracy. The Engineer may refuse to allow the commencement of the testing if this documentation is not available at the test site.

15.3.5 Failures The Contractor shall correct all faults found during testing, and shall arrange for the test to be repeated. The test shall only be repeated when the fault has been remedied and the equipment demonstrated to functioning correctly.

Where remedial measures involve significant modifications that might, in the Engineer's opinion, affect the validity of earlier tests, then the Contractor shall repeat the earlier tests and obtain satisfactory results before repeating the test in which the fault was first identified.

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The Engineer shall have the right to order the repeat or abandonment of any test in the event that results demonstrate that the equipment is significantly non-compliant with the Contract requirements, without in any way prejudicing his rights.

The Engineer shall have the right to suspend any test in the event that errors or failures have become unacceptable. The Engineer shall also have the right to suspend any test in the event of a fault being detected by the Contractor but not reported to the Engineer within 24 hours. In this event, the suspension shall remain in effect until reporting has been brought up to date to the satisfaction of the Engineer.

Any costs incurred by the Employer or the Engineer in connection with inspection and re-testing as a result of a failure of the subject under test, or damage during transport, or erection on site before take-over by the Employer, shall be to the account of the Contractor.

15.4 Tests During Commercial Operation

After the plant has passed the site tests required under this Contract, and has become available for commercial operation, certain additional tests may be carried out in order to investigate the response and recovery of the system during events such as the switching of various items of plant, system faults and load rejection.

15.5 Documentation

The Contractor or his sub-Contractors shall supply to the Engineer, as soon as practicable after works tests, commissioning and site tests have been witnessed, the original plus five copies of the relevant test certificates. These shall contain details of each test performed as required by the Engineer; records, results and calculations of all electrical tests.

15.6 Tests at Manufacturer’s Works

Test at manufacture's work shall comprise type tests and routine tests.

(a) Type test:

These tests are in general those detailed in the IEC, which pertain to the equipment being tested. Type tests are to prove the general design of the equipment and the manufacturer may submit test certificates of tests, which have been carried out on identical equipment. Not withstanding any provision in an IEC the inspector shall have the right to accept such certificate in lieu of the specified type test or to reject them.

The type test prescribed shall be carried out in all cases where such certificates are not available or are rejected.

Unless otherwise stated, type tests when called for shall be made on equipment which has previously passed its routine tests.

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(b) Routine Tests Routine tests should be carried out on the following specific equipment and in accordance to the latest issue of IEC specifications.

All materials used shall be subjected to and shall withstand satisfactorily such routine tests as are customary in the manufacture of the types of plant included in the Contract Works.

15.7 Specific Equipment Tests

This section of this schedule lists inspections, works and site tests which the Engineer requires for specific equipment, but this shall not preclude the Engineer's right to call for further tests if he considers these necessary.

15.7.1 Transformers Routine, type and special tests shall be carried out in accordance with IEC 60076. The following additional tests shall be made.

15.7.1.1 Tests in the Manufacturer's Works The tests shall be arranged to represent working conditions as closely as possible.

Unless otherwise stated, type tests when called for shall be made on equipment which has previously passed its routine tests.

15.7.1.2 Routine tests (a) The winding resistance and impedance voltage tests should also be carried out at all tapping

positions.

(b) Magnetic circuit insulation.

(i) A power frequency voltage of 2 kV for 1 minute applied as follows:-

Core bolts to core, to yoke clamps and to core leg side plates.

Core to yoke clamps and to core leg side plates.

(ii) Immediately prior to despatch, 2 kV for 1 minute applied between core and earth. A megger may be used for this test.

(c) No load current at:-

(i) 90 per cent rated voltage.

(ii) 100 per cent rated voltage.

(iii) 110 per cent rated voltage.

(iv) The maximum voltage equivalent to the value quoted in the Schedules.

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(d) Lightning impulse test on all terminals including neutral.

(e) Dissolved gas analysis: A dissolved gas analysis test shall be carried out before and after a temperature rise test and before and after the series of dielectric tests. The tests shall be in accordance with IEC 60567 and IEC 60599.

(f) Voltage ratio, polarity and phase relationship tests: The voltage ratio shall be measured at each tapping. The polarity and phase relationship (vector group) of each transformer shall be checked.

15.7.1.3 Type Tests (a) The lightning impulse chopped wave test: Tests shall be carried out on all windings of 300 kV

and above in accordance with IEC 60076-3 Clause 13.

(b) Transferred surge: The transformer shall be tested so that with the test voltage, applied to the other windings, the maximum surge that can be transferred to the unloaded winding(s) does not exceed its specified insulation lever. Compliance with this requirement may be achieved by the use of external equipment connected to the unloaded winding and shall be proved by recurrent surge oscillograph measurements, by comparison with the transferred voltage on open circuit.

(c) Noise level: The level of noise shall be measured in accordance with IEC 60551.

(d) The measurement of zero sequence impedance shall be carried out in accordance with IEC 60076-1 sub clause 8.7.

(e) During the temperature rise test the accuracy of oil and/or winding temperature indicating devices shall be determined.

(f) The following transformer “footprint” test shall be carried out prior to leaving the works,

Capacitance and power factor measurements (Doble tests) Transformer winding frequency response analysis (FRA) Recovery voltage measurements (RVM) or equivalent

15.7.1.4 Transformer Site Tests The site tests, full details of which are to be submitted by the Contractor after the Contract has been placed, shall include those tests described in outline below.

(a) Insulation resistance of core and windings.

(b) Dielectric strength of oil samples.

(c) Ratio and no-load current at low voltage (e.g. 380 V) on all tappings.

(d) Vector relation check.

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(e) Calibration check of temperature instruments, including secondary current injection and proving contact settings.

(f) Air injection tests of gas/oil-actuated relays.

(g) Setting check of oil-level and oil-flow devices.

(h) Complete functional tests of cooling equipment and tap-change equipment, including manual/automatic sequences, indications, alarms and interlocks, measurement of motor currents, adoption of suitable motor protection settings and proof of protection for stalled or single-phasing conditions.

(j) Operational tests of "freeze-drier" type breathers.

(k) Insulation resistance of all secondary circuits.

(m) Repeat “footprint” tests to confirm that no damage to the windings has taken place during transit and installation.

(n) Final checks before energising:-

(p) Venting, position and locking of valves, earthing of star-point(s) and of tank, state of breathers and of pressure-relief devices, oil levels, absence of oil leakage, operation of kiosk heaters, tap-change counter readings, resetting of maximum temperature indicators, final proving of alarms and trips.

(q) Dissolved Gas Analysis of transformer oil after final processing

(r) Tests when energised:-

On-load tap-changer operation throughout range (subject to not exceeding 1.1 pu volts on any windings).

Maintenance of 1.1 pu volts on untapped windings for 15 minutes (but not exceeding this value on tapped winding).

(s) Tests on load:-

Temperature instrument readings.

Measurement of WTI CT secondary currents.

Repeat Dissolved Gas Analysis of transformer oil after energisation tests completed

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15.7.2 Reactors Routine and type tests shall be carried out in accordance with IEC 60289. The following additional tests shall be made.

15.7.2.1 Routine Tests (a) Magnetic circuit insulation (where appropriate).

(i) A power frequency voltage of 2 kV for 1 minute applied as follows:-

Core bolts to core, to yoke clamps and to core leg side plates.

Core to yoke clamps and to core leg side plates.

Clamping bolts to screens and screens to earthed metal paths from which the screens are isolated.

(ii) Immediately prior to despatch, 2 kV for 1 minute applied between core and earth. A megger may be used for this test.

(b) Noise level: The level of noise shall be measured in accordance with IEC 60551.

(c) Vibration: Vibration measurements shall be taken and the level recorded shall be subject to approval. This test shall be carried out unless it can be shown to the satisfaction of the Engineer that the level of vibration in the reactor and its auxiliaries is harmless.

(d) Voltage/reactance characteristics shall be recorded from 50 per cent to 100 per cent in steps of 10 per cent rated voltage. Reactance values up to 130 per cent rated voltage shall be determined by test or calculation.

(e) DIssolved gas analysis: A dissolved gas analysis test shall be carried out before and after a temperature rise test and before and after the series of dielectric tests. The tests shall be in accordance with IEC 60567 and IEC 60599

(f) The following “footprint” test shall be carried out prior to leaving the works,

Capacitance and power factor measurements (Doble tests)

Transformer winding frequency response analysis (FRA)

Recovery voltage measurements (RVM) or equivalent.

15.7.2.2 Type Test (a) Switching surge: In accordance with IEC 60076-3.

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15.7.3 Reactor Site Tests (Minimum) (a) Insulation resistance of core and windings.


(c) Dissolved Gas Analysis of transformer oil after final processing

(d) Calibration check of temperature instruments and proving contact settings.

(e) Air injection tests of gas/oil-actuated relays.

(f) Setting check of oil-level and oil-flow and water-flow devices.

(g) Operational tests of "freeze-drier" type breathers.

(h) Insulation resistance of all secondary circuits.

(j) Repeat “footprint” tests to confirm that no damage to the windings has taken place during transit and installation.

(k) Final checks before energising:-

(m) Venting, position and locking of valves, earthing of star-point(s) and of tank, state of breathers and of pressure-relief devices, oil levels, absence of oil leakage, operation of kiosk heaters, resetting of maximum temperature indicators, final proving of alarms and trips.

(n) Tests when energised:-

Maintenance of 1.1 pu volts on untapped windings for 15 minutes.

Temperature instrument readings.

Repeat Dissolved Gas Analysis of reactor oil after final processing

15.7.4 Transformer & Reactor Related Equipment 15.7.4.1 Voltage Control Equipment Routine and type tests shall be carried out in accordance with IEC 60214.

15.7.4.2 Cable Boxes and Disconnecting Chambers (a) Routine test

Oil tightness - All cable boxes and disconnecting chambers shall be tested with oil, having a viscosity not greater than that of IEC 60296 insulating oil when at a temperature of 15°C, at a pressure of 70 kN/m2 for 12 hours; during this time no leakage shall occur nor shall there be any permanent set when the pressure is released.

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15.7.4.3 Bushings Routine, type, sample and special tests shall be carried out in accordance with IEC 60137 and IEC 60233.

15.7.4.4 Tanks and ONAN Coolers (a) Routine tests

(i) Oil leakage - All tanks and oil filled compartments including all forms of radiator but excluding separate coolers using forced oil circulation, (for which see Section 8 below) shall be tested for oil tightness by being completely filled with oil of a viscosity not greater than that of IEC 60296 insulating oil at a temperature of 15°C and subjected to a pressure equal to the normal pressure plus 35 kN/m2. This pressure shall be maintained for a period of not less than 24 hours, during which time no leakage shall occur.

(ii) The tap-changer barrier shall be subjected to normal oil pressure head for 24 hours,

during which time there shall be no leakage from the panel or bushings.

(iii) Detachable radiators may be tested as separate units.

(b) Type tests

(i) Vacuum:

(1) One transformer tank, one reactor tank, tap-changing compartment, radiator and cooler of each type shall be subjected when empty of oil to that vacuum test level specified in the Schedules. There shall be no permanent deflection of the stiffeners, nor shall the permanent deflection of the panels exceed the value specified in the following table.

Major dimension of panel between stiffeners (metres) vertical or horizontal

Maximum permanent deflection

Up to 1.5 m 3 mm

1.5 m – 3 m 8 mm

Above 3 m 13 mm

(2) A further test a vacuum equivalent to 3 m bar absolute pressure for a period of

8 hours shall be made for the purpose of checking the mechanical withstand capability of the tank; during this test no damage or fractures shall occur. This test may be combined with other tests or made during the processing of the unit.

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(ii) Pressure:

(1) One transformer tank and one reactor shall be subjected to a pressure corresponding to the normal pressure plus 35 kN/m2. After the release of the excess pressure there shall be no permanent deflection of the stiffeners nor shall the permanent deflection of panels between stiffeners exceed the value specified in the above table. This test may be combined with a routine oil leakage test.

(2) The tap-changer barrier shall be shown to withstand an over pressure test of normal pressure plus 35 kN/m2 for 12 hours.

(c) Pressure relief device

When required by the Engineer one pressure relief device of each size shall be subjected to increasing oil pressure and shall operate before reaching normal pressure plus 35 kN/m2.

The operating pressure shall be recorded on the test certificate.

15.7.4.5 Cooling Plant with Forced Oil Circulation (a) Routine tests

(i) Air/oil coolers - All coolers using forced oil circulation shall be filled with oil of a viscosity not greater than that of IEC 60296 insulating oil at a temperature of 15°C and subjected to a pressure equal to twice the maximum working pressure at the inlet to the cooler under service conditions which shall be maintained for a period of not less than 24 hours; during this time no leakage shall occur.

(b) Type tests

(i) One forced-oil cooler of each type shall be subjected, when empty of oil, to that vacuum test level specified in the Schedules. There shall be no permanent deformation or distortion of any part of the cooler.

15.7.4.6 Pressure relief device When required by the Engineer one pressure relief device of each size shall be subjected to increasing oil pressure and shall operate before reaching normal pressure plus 35 kN/m2.

The operating pressure shall be recorded on the test certificate.

15.7.4.7 Fans, Pumps, Motors, Pipework, Oil Sampling Devices and Valves (a) Routine tests

(i) Oil filled equipment - The bodies of all oil pumps complete with submerged motors, if any, and the oil pipework, oil sampling devices and valves shall withstand an hydraulic pressure of 140 kN/m2 for 15 minutes.

(ii) Fans - Static and dynamic balance shall be checked on all fan impellers.

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(iii) Control gear - All control gear shall be subjected to the tests specified in the appropriate IEC.

(iv) Motors - Each machine shall be subjected to the following tests where applicable:-

(1) Measurement of winding resistance (cold).

(2) No load test at rated voltage for determination of fixed losses.

(3) An overvoltage test at 1.5 times rated voltage applied with the machine running at no load, for a period of 3 minutes, to test interturn insulation.

(4) High voltage in accordance with IEC 60034-1.

(b) Type tests

(i) Motors - Performance tests shall be in accordance with IEC 60034-1 however, certificates of type tests in accordance with IEC will be accepted.

(ii) Except for non-return valves, all valves and oil sampling devices which are subject in service or during maintenance to oil pressure shall withstand, when empty of oil, absolute pressure not exceeding 350 m bars. In the case of valves this test is to be applied to the body only. This type test shall subsequently be followed by a repeat oil leakage test.

15.7.4.8 Oil (a) Sample tests

Samples of oil from each consignment shall be tested in accordance with IEC 60296 before despatch.

Subject to the agreement of the Engineer a test certificate, confirming that the oil from which the consignment was drawn has been tested in accordance with IEC 60296, may be accepted. Before commissioning any transformer, the electric strength of its oil shall be check-tested and a Dissolved Gas Analysis shall be taken and the results approved by the Engineer.

15.7.4.9 Gas and Oil Actuated Relays (a) Routine tests

The following tests shall be made on relays when completely assembled. Where oil is referred to it shall have a viscosity not greater than that of IEC 60296 insulating oil at 15°C.

(i) Oil leakage - The relay, when filled with oil shall be subjected to an internal pressure of 140 kN/m2 for 15 minutes. No leakage shall occur either from the casing or into normally oil free spaces, such as floats, within the casing.

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(ii) Gas collection:

(1) With the relay mounted as in service and at a rising angle of 5 degrees (tank to conservator) and full of oil, gas shall be introduced into the relay until the gas collection contacts close. The oil level contacts shall not close when gas is escaping freely from the relay on the conservator side. These contacts shall, however, close when the pipework is empty of oil.

(2) the empty relay shall be tilted, as if mounted in pipework rising from tank to conservator, at an increasing angle until the gas collection contacts open. The angle of tilt shall then be reduced and the gas collection contacts shall close before the angle is reduced to less than 13 degrees to the horizontal.

(3) With the relay mounted at a falling angle of 16 degrees to the horizontal and full of oil, the gas collection contacts shall be open.

(iii) Oil surge - With the relay mounted as in service and full of oil at approximately 15°C the surge contacts shall close within the steady oil flow limits specified in the Schedules. This option shall not be adversely affected when the gas collection contacts have already closed and gas is escaping freely.

(iv) Voltage - With the relay empty of oil, a voltage of 2 kV shall be applied in turn between each of the electrical circuits and the casing for one minute, the remaining circuits being connected to the casing.

(v) Operation - With the transformer assembled with its cooling plant as in service, tests shall be made to demonstrate that the relay does not operate whilst the oil pump motors are being started or stopped.

(b) Sample test

At the discretion of the Engineer, the following test shall be made: -

(i) Variation of performance with mounting angle with the mounting conditions as in service, the mounting angle shall be varied within the rising angle limits 1 and 9 and tests repeated in the manner prescribed for the routine tests.

15.7.4.10 Secondary Wiring All secondary wiring, including panel wiring and control circuits and all apparatus connected thereto shall be subjected to the following tests:

(a) Routine tests

(i) Voltage - 2 kV applied for one minute except where this requirement is modified by a British Standard, to which item the appropriate test shall be applied.

(ii) Insulation resistance - By megger of not less than 500 volts.

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15.7.4.11 Galvanizing (a) Sample tests

Samples selected by the Engineers of all galvanized material shall be subjected to the galvanizing tests set out in either BS 443 or BS 729, whichever is applicable.

15.7.4.12 Oil Filtering Equipment Such tests as are considered necessary by the Engineer to show that the guaranteed particulars in the Schedules are met.

15.7.4.13 Minimum Acceptable Transformer Site Tests The site tests, full details of which are to be submitted by the Contractor after the Contract has been placed, shall include those tests described in outline below:

(a) Insulation resistance of core and windings.


(c) Ratio and no-load current at low voltage (e.g. 380 V) on all tappings.

(d) Vector relation check.

Calibration check of temperature instruments, including secondary current injection and proving contact settings.

(e) Air injection tests of gas/oil-actuated relays.

(f) Setting check of oil-level and oil-flow devices.

(g) Complete functional tests of cooling equipment and tap-change equipment, including manual/automatic sequences, indications, alarms and interlocks, measurement of motor currents, adoption of suitable motor protection settings and proof of protection for stalled or single-phasing conditions.

(h) Operational tests of "freeze-drier" type breathers.

(i) Insulation resistance of all secondary circuits.

(j) Repeat “footprint” tests to confirm that no damage to the windings has taken place during transit and installation.

(k) Final checks before energising:-

(i) Venting, position and locking of valves, earthing of star-point(s) and of tank, state of breathers and of pressure-relief devices, oil levels, absence of oil leakage, operation of kiosk heaters, tap-change counter readings, resetting of maximum temperature indicators, final proving of alarms and trips.

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(ii) Dissolved Gas Analysis of transformer oil after final processing

(l) Tests when energised:-

(i) On-load tap-changer operation throughout range (subject to not exceeding 1.1 pu volts on any windings).

(ii) Maintenance of 1.1 pu volts on untapped windings for 15 minutes (but not exceeding this value on tapped winding).

(m) Tests on load:-

(i) Temperature instrument readings.

(ii) Measurement of WTI CT secondary currents.

(iii) Noise measurement tests

(iv) Repeat Dissolved Gas Analysis of transformer oil after energisation tests completed

15.7.5 GIS Switchgear 15.7.5.1 Circuit Breaker Inspection & Testing Type and routine tests shall be carried out strictly in accordance with IEC 62271-200, IEC 60694, IEC 62271-100, IEC 60427, IEC 60060, IEC 60270, IEC 62771-110 and any other relevant standards and requirements of this Specification where appropriate.

15.7.5.2 Circuit Breaker Type Tests The following type tests shall be performed:

(a) Dielectric test on main circuit - Lightning impulse, Power frequency voltage withstand tests, Partial discharge and Radio interference voltage (r.i.v) tests

(b) Dielectric test on auxiliary and control circuit

(c) Temperature rise test

(d) Measurement of the resistance of the main circuit

(e) Short-time and peak withstand current tests

(f) Short-circuit making and breaking, out-of-phase making and breaking, critical current and capacitive and inductive (reactor) current switching tests

(g) Internal arcing test

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(h) Mechanical endurance, environmental operation tests

(j) Electromagnetic compatibility (EMC) tests

(k) Verification of the degree of protection and tightness tests

(m) Any other tests in accordance with the above standard

15.7.5.3 Circuit Breaker Capacitive Current Switching Tests The capacitive current switching duty specified in the Schedules for the circuit breaker shall be tested in accordance with IEC 62271-100. Test evidence shall be submitted to confirm that the highest over voltage during any switching duty does not exceed 2.5 p.u. by either performing the relevant tests or by submitting the relevant type test reports to the satisfaction of the Ministry of Electricity.

15.7.5.4 Circuit Breaker Low Inductive Current Switching Tests A series of switching tests shall be made to IEC 62771-110 on each type of circuit breaker being supplied in order to demonstrate its performance when switching transformer magnetising currents and reactor currents. Test evidence shall be submitted to confirm that the highest over voltage during any switching duty does not exceed 2.5 p.u. by either performing the relevant tests or by submitting the relevant type test reports to the satisfaction of the Ministry of Electricity.

In addition to the above, additional, low inductive current switching test evidence of 10, 50, 100 amp currents, in accordance with IEC 62771-110 under site conditions, to confirm that the highest over voltage during any switching duty does not exceed 2.5 p.u.

15.7.5.5 Circuit Breaker Internal Arcing Tests Internal arcing tests shall be carried out in accordance with IEC 60298 - Annex AA. The test evidence for each compartment shall confirm that the equipment satisfies the IEC test criteria that the internal arcing fault in one compartment does not affect the adjacent compartments and in particular the relay compartment.

15.7.5.6 Circuit Breaker Routine Tests The following routine tests shall be performed:

(a) Dielectric test on the main circuit - Dry power frequency voltage withstand, Partial discharge and Radio interference voltage (r.i.v) tests

(b) Voltage withstand tests on auxiliary and control circuits

(c) Measurement of the resistance of the main circuits

(d) Mechanical operating tests

(e) Pressure and Gas tightness tests

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(f) Design and visual checks

(g) Inspection of the general condition

(h) Timing tests of the main contacts and auxiliary switches

(j) Complete electrical functioning tests

(k) Closing and opening check at reduced voltage and other necessary tests and verifications

15.7.5.7 Circuit Breaker Site Tests As a minimum, the following tests after installation on site shall be performed:

(a) Power frequency voltage tests on the main circuits

(b) Dielectric tests on auxiliary circuits


(d) Gas tightness tests

(e) Design and visual checks

(f) Measurement of gas condition

(g) Mechanical operation tests

(h) Secondary injection tests on all protection relays

(j) Primary inject tests on all protection relays and associated current transformer circuits

(k) Complete electrical functioning tests including the function of all interlocks

15.7.6 Disconnectors and Earthing Switches All tests shall be performed in accordance with IEC 62271-100, IEC 60427, IEC 60694, IEC 60060, IEC 60270, IEC 62771-110 and other relevant IEC standards.

15.7.6.1 Type Tests The following type tests shall be performed:

(a) Lightning impulse tests

(b) Power frequency voltage withstand wet and dry tests

(c) Partial discharge tests

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(d) Dielectric test on auxiliary and control circuit

(e) Temperature rise test

(f) Measurement of the resistance on the main circuit

(g) Short-time and peak withstand current tests

(h) Tests to prove the short-circuit making and breaking, performance of earthing switches (as applicable)

(j) Operating and mechanical endurance tests

(k) High temperature operation tests

(m) Artificial pollution tests

(n) Radio interference voltage test.

15.7.6.2 Routine Tests The following routine tests shall be performed:

(a) Power frequency voltage withstand dry tests on the main circuit.




15.7.6.3 Site Tests The following tests shall be performed :

(a) Inspection of the general condition

(b) Manual and electro/mechanical closing and opening tests

(c) Closing and opening tests at the reduced voltage

(d) Checking of operating time

(e) Control and interlock checks.

and other necessary checks and verifications.

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15.7.7 Current Transformers (CT’s) Testing shall be in accordance with IEC 60044-1 plus any additional tests indicated in this section and the schedules.

15.7.7.1 Type Tests (a) Short-time current test: Test data for similar units supported by calculation and equivalent

static load tests may be acceptable.

(b) Temperature rise test

(c) Lightning impulse test

Um < 300 kV: 15 positive plus 15 negative

Um ≥ 300 kV: 3 positive plus 3 negative

(d) Switching impulse test: 15 positive impulses applied wet for outdoor equipment, (applies to transformers with Um ≥ 300 kV).

(e) Wet dielectric tests:

Um < 300 kV: Power frequency test

Um ≥ 300 kV: Switching impulse test

(f) Determination of errors

(g) Radio interference test (RIV):

(h) Proof of Class PX low reactance

15.7.7.2 Routine Tests (a) Verification of terminal markings.

(b) Power-frequency withstand on primary.

(c) Partial discharge measurement

(d) Power-frequency withstand on secondary winding

(e) Determination of errors

(f) Class PX magnetising curves

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15.7.7.3 Special Tests The following special category tests are required:

(a) Chopped lightning impulse

(b) Measurement of capacitance and dielectric dissipation factor

(c) Mechanical tests

15.7.7.4 Site Tests (a) Inspection of the general condition

(b) Secondary winding resistance measurement and burden checks.

(c) Ratio checks

(d) Magnetisation curves

(e) Insulation resistance measurements to earth and between windings.

15.7.8 Voltage Transformers and Coupling Capacitors Inductive voltage transformers (IVTs) shall be tested in accordance with IEC 60044-2. Capacitor voltage transformers shall be tested in accordance with IEC 60186 and any additional tests identified in the Publicly Available Standard PAS/IEC 60044-5. For coupling capacitors IEC 60358 shall apply.

15.7.8.1 Type Tests (a) Short-time current test

(b) Temperature rise test

(c) Lightning impulse test

Um < 300 kV: 15 positive plus 15 negative

Um ≥ 300 kV: 3 positive plus 3 negative

(d) Switching impulse test: 15 positive impulses applied wet for outdoor equipment, (applies to transformers with Um ≥ 300 kV).

(e) Wet dielectric tests:

Um < 300 kV: Power frequency test

Um ≥ 300 kV: Switching impulse test

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(f) Determination of errors

(g) Radio interference test (RIV)

(h) Transient response test (CVTs only)

(j) Ferro-resonance test (CVTs only)

(k) Tightness of electromagnetic unit (CVTs only)

15.7.8.2 Routine Tests (a) Verification of terminal markings.

(b) Power-frequency withstand on primary (IVT only).

(c) Partial discharge measurement

(d) Power-frequency withstand on secondary winding and between sections

(e) Determination of errors

The following additional tests are required for CVTs:

(i) Tightness of capacitor voltage divider

(ii) Power-frequency test on the electromagnetic unit

(iii) Power frequency test on low voltage terminal

(iv) Ferro-resonance check

15.7.8.3 Special Tests The following special category tests are required:

(a) Chopped lightning impulse

(b) Measurement of capacitance and dielectric dissipation factor

(c) Mechanical tests

(d) Tightness of capacitor units (CVTs only)

15.7.8.4 Site Tests (a) Inspection of general condition

(b) Insulation resistance measurements to earth and between windings.

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(c) No-load test with normal applied voltage on secondary terminals for a minimum of 30 minutes (IVTs only).

(d) Ratio checks

(e) Burden checks

15.7.9 Insulating Oil, Sulphur Hexafluoride and Compound 15.7.9.1 Insulating oil Samples of oil from each consignment shall be tested and shall comply with the tests specified in IEC 60296 for insulating oils, before any oil is despatched.

15.7.9.2 Sulphur Hexafluoride Samples of SF6 from each consignment shall be tested and shall comply with the tests specified in IEC 60376 and 60480, before any SF6 gas is despatched.

15.7.9.3 Compound Samples of compound selected by the Engineer from the bulk shall be tested to prove compliance with the requirements of BS 1858 for the appropriate grade of compound.

15.7.10 Surge Diverters 15.7.10.1 Tests on Surge Diverters (a) Zinc oxide, gapless type

Type, routine and standard acceptance tests shall be carried out in accordance with the IEC 60060, 60270 and 60099 metal oxide surge arresters.

Type test certificates will be accepted subject to their approval.

15.7.10.2 Tests on surge counters (a) Minimum Current Operation Tests

The rated minimum operating current of the counter, stated in the schedules, shall be passed ten times and the counter shall correctly register these operations.

(b) Maximum Current Withstand Tests

The maximum rated current stated in the schedules with a 8/20 µsec wave shape shall be applied to the counter ten times without any cooling periods and the counter shall register and withstand without distress.

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15.7.11 Line Traps Each design of line trap being supplied shall indicate the class of insulation used and shall be subjected to the type and routine tests specified in IEC 60353 and the additional requirements as follows:-

The current used for the temperature rise test shall be not less than the rated current of line trap.

The current duration for the short time current test shall be not less than that stated in the schedules.

15.7.12 AIS Busbar Conductor and Connections The tests shall be in accordance with IEC 61089.

15.7.13 Post Insulators Each type of post insulator being provided shall be type, sample and routine tested in accordance with IEC 60168, 60660 and the following supplementary tests:-

15.7.13.1 Radio Influence Voltage Type Test Each type of post insulator being provided shall be assembled as in service and subjected to radio influence voltage test in accordance with NEMA Publication 107, IEC 60060 and IEC 60437.

15.7.14 Insulator Strings Type, sample and routine tests on insulators of the string type, porcelain or glass, shall be made in accordance with the requirements of IEC 60383 and 60815 and the supplementary type tests stated below.

15.7.14.1 Dielectric Tests The 50 per cent flashover level as well as withstand shall be determined during the impulse and power frequency tests.

15.7.14.2 Radio Influence Voltage Test Each type of string insulator shall be assembled as in service and subjected to radio influence voltage tests in accordance with NEMA 107, IEC 60060, 60437 and this Specification.

15.7.15 Tension and Suspension Clamps and Joints 15.7.15.1 Type Tests All joints and clamps shall be submitted for examination before test and all assembly, cutting off of conductor, compound filling (where applicable), and any work whatsoever necessary for the assembly of the clamps and joints in the field shall be carried out in the presence of the Engineer with the erection methods and tools proposed for field use. Approval of such methods and tools will be subject to inspection at the time of the tests. The Contractor shall ensure that a reasonable number of his supervising staff shall be present at the type tests.

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(a) Mechanical type test

The following tests shall be carried out on the conductor clamps and joints:-

(i) Two tension clamps shall be fitted to the end of a length of conductor not less than 6 metres long.

(ii) A tension joint shall be fitted in the centre of a 6 metre length of conductor, each end of which shall be held in a half joint.

For both tests (i) and (ii) a tensile load of about 50 per cent of the breaking load of the conductor shall be applied and the conductor shall be marked in such a way that movement relative to the fitting can easily be detected. Without any subsequent adjustment of the fitting, the load shall be steadily increased to 95 per cent of the breaking load and then reduced to 90 per cent of the breaking load and maintained for one minute. There shall be no movement of the conductor relative to the fitting due to slip during this one minute periods and no failure of the fitting.

A slip test shall be carried out on suspension clamps to demonstrate compliance with this Specification and to establish the torque to be applied to the clamp bolt nuts.

Non-tension joints and clamps, and non-tension parts of tension clamps shall be similarly tested to show compliance with this Specification.

(b) Electrical Type Tests

The following test shall be carried out on a sample each of tension joints, tension clamps in which the conductor has necessarily to be cut, and non-tension joints. The test shall be carried out on an assembly consisting, where applicable, of a tension clamp, tension joint and non-tension joint, together with a length of the line conductors, the whole being connected in series. The lengths of intermediate conductor shall be cut so that the distance between the mouths of the test fittings shall not be less than 1 metre. The assumed maximum full load current specified in the Schedules at 50 Hz shall be passed continuously through the assembly for a period of 8 hours, followed by approximately 16 hours shutdown, followed by a further 8 hours heat run. At approved intervals throughout this period measurements of temperature rise shall be recorded on the fittings and on the intermediate conductors. Immediately at the ends of the heat-runs accurate voltage drop measurements shall be made on standard lengths, including fittings and conductor. If possible a.c. voltage drop measurements shall also be made during the heat runs. The temperature rise and resistance per unit length of any fitting shall at no time exceed those of the conductors. Temperature measurements on fittings and conductors shall be made in an approved manner. No tightening up or adjustment of fittings in any way shall be permissible during the progress of the test.

At the conclusion of the test all fittings shall be completely dismantled and there shall be no signs of local heating, burning or fusing on any part of the fittings or on the conductor itself.

All conductor fittings shall be shown to comply with the visible corona and RIV levels specified.

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15.7.15.2 Sample Tests Sample clamps and joints shall be submitted to such tests as the Engineer may require in order to demonstrate compliance with this Specification.

15.7.16 Large Hollow Porcelains Each type of large hollow porcelain being supplied shall be subjected to the routine and sample tests specified in IEC 60233, modified and supplemented as follows:-

15.7.16.1 Routine Pressure Test Each hollow porcelain being provided shall be subjected to the appropriate routine hydraulic pressure tests in accordance with the requirements of this Specification. The test shall be made on the porcelain complete with irremovable metallic flanges.

15.7.16.2 Temperature Cycle Test These tests shall be made on the porcelain complete with all irremovable fittings.

15.7.16.3 Routine Bending Test If the stress expected on the porcelain in service exceeds 20% of the minimum failing load then the following routine test shall be made:-

Each porcelain shall be subjected to a cantilever bending test such that the insulator is fully stressed in all directions, but in the event of a point loading procedure being adopted and the number of points at which the load is applied shall be a minimum of four. The applied bending moment, arrangement for test, and test procedure shall be to the approval of the Engineer.

15.7.16.4 Sample Bending Test When the porcelain service stress is less than 20 per cent of the minimum failing load then sample bending tests shall be made as specified. Samples shall be selected as specified in IEC 60233.

15.7.16.5 Ultrasonic Tests Routine tests shall be made on each porcelain insulator being supplied using ultrasonic crack detection techniques. These tests shall be made on the insulator prior to fitting of metallic flanges.

15.7.17 Bushing Insulators Type and routine tests on bushing type insulators shall be made in accordance with the requirements of IEC 60137 modified and supplemented as stated below.

The test voltages shall be as specified in the Schedules.

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15.7.17.1 Type Tests (a) Short time current test

Each type of bushing being provided shall be subjected to a short time current test at the rating specified in the Schedules, the test procedure being in accordance with that of IEC 56. The following measurements shall be made after this test to demonstrate that the bushing is in a sound condition.

(i) Power Factor (Loss Angle) - Voltage characteristic up to 120 per cent of normal working voltage.

(ii) Internal Discharge Test and Applied Voltage of 0.67 E - The results of these tests shall not differ significantly from those obtained during routine tests on the same design of bushing.

(b) Internal discharge and power factor tests

These tests shall be made on each bushing being type tested in the manner specified. The internal discharge test shall be made before and after the power frequency impulse and switching impulse voltage type tests, but the power factor measurements need only be made after these tests.

15.7.17.2 Routine Tests (a) Sequence of routine tests

The routine dielectric tests shall be made in the following order: -

(i) Internal discharge test as specified.

(ii) Dielectric loss angle measurement as specified.

(iii) Power frequency dry voltage test.

(iv) Dielectric loss angle measurement as specified.

(v) Internal discharge test as specified.

(b) Internal discharge test

Each bushing shall be assembled complete as in service, and subjected to an internal discharge test as specified in IEC 60137.

(c) Dielectric loss angle measurements

Measurement shall be made of the dielectric loss angle and capacitance of the primary insulation between line terminal and test tapping or metallic flange of each complete bushing using a Schering Bridge.

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The loss angle voltage characteristic shall be determined over a voltage range of up to 1.2 times phase to neutral voltage.

The loss angle measured shall not change with voltage and shall not exceed the value guaranteed in the Schedules.

15.7.18 Structures A representative sample of each type of support structure being provided shall be assembled prior to dispatch to site and loads simulating the specified design parameters shall be applied.

Such loads shall be withstood without deformation of any structure member.

15.7.19 132, 33 and 11 kV Power Cables 132/33/11 kV cable and cable accessories should be tested together as a complete system for type test purposes. Commissioning tests will inherently test these components as a complete system.

15.7.19.1 Type Tests The appropriate type tests in full accordance with IEC 60840 and IEC 60502 and shall be made available in order to demonstrate satisfactory performance requirements.

These tests excepting those which are also required as additional regular tests need not be repeated once they have been performed successfully, unless alterations are made to cable design or materials which might affect the performance.

The accessory manufacturer must demonstrate by type test approval tests on the specific cable that any joint or termination that it is intended for use with the cable supplied for a specific contract is compatible with that cable.

Designs suitably tested may be used for applications where the electrical design stresses are the same or lower than those tested.

The tests are based upon a maximum continuous design conductor temperature of 90°C. Where enhanced or emergency conductor temperatures are to be offered modification of these tests may be required.

15.7.19.2 Routine Tests Routine tests shall be conducted in accordance with IEC 60840 and IEC 60502 as appropriate.

General

The following routine tests shall be carried out on each drum length of cable to be supplied:

(a) Dimensional Checks.

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(b) Measurement of Conductor D.C. Resistance.

(c) Measurement of Capacitance.

(d) D.C. Voltage Test on Oversheath.

(e) Partial Discharge Test.

(f) Insulation A.C. Voltage Withstand Test.

The test methods and requirements for items (a), (e) and (f) are as follows: -.

(a) Dimensional Checks

A measurement of the thickness of the insulation, metallic sheath and oversheath shall be carried out on every drum length of cable. The checks of cable construction are specified in IEC 60840 Clause 11.4.1.

The thickness of the semi conducting screen shall be measured as specified in IEC 60811-1-1. The minimum thickness shall not be less than 60% of the declared nominal value.

(e) Partial Discharge Test

The cable shall be tested for partial discharge as specified in IEC 60840 Clause 11.3.5.

All production cable is expected to be discharge-free and any partial discharge detected will require evidence of investigation and explanation.

(f) Insulation A.C. Voltage Withstand Test

The test shall be carried out on all cables as prescribed in IEC 60840 and IEC 60502 as shown below. No breakdown of the insulation shall occur.

System Voltage ( kV) Power Frequency Test Voltage ( kV) Duration (min)

132 2.5.U0] 30

33 3.5.U0 5

11 3.5.U0 5

(g) Pre-moulded Accessory Tests

Every pre-moulded accessory shall be assembled on a suitable former and shall be subject to a routine test at 2 U0 for 1 h. It shall not breakdown. During the test the assembled accessory shall be monitored for partial discharge with a background noise level no greater than 2 pC. After testing every component shall be inspected for signs of electrical discharge. Any evidence of partial discharge or visible damage shall be brought to the attention of NGC and included in the test report. Only sound and visually inspected components shall be packed for delivery to site.

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15.7.19.3 Tests on a Dispatch Drum of Cable The following tests shall be carried out on dispatch drum of cable, to check that the whole of each length complies with the requirements.

(a) Voltage test: Each drum length of completed cable shall withstand a voltage of 25 kV DC for one minute between the metal sheath and the external conducting surface.

(b) Partial discharge test

(c) Dielectric loss angle

(d) Conductor examination

(e) Measurement of electrical resistance of conductor

(f) Oversheath voltage withstand test

15.7.19.4 Site Test Requirements (a) D.C. Conductor Resistance Measurement

The ambient temperature and d.c conductor resistance of each completed circuit shall be measured to at least three significant figures and recorded.

(b) Sheath Insulation D.C. Voltage Withstand Test

The fully insulated sheath system including cable oversheath, terminal base insulation, joint external and sectionalising insulation if present, together with the insulation of bonding leads and link boxes or pillars, shall withstand a voltage of 10 kV d.c applied between sheath and earth for a period of one minute.

The maximum leakage current shall not exceed 10 mA. Current above this level is indicative of an oversheath fault.

(c) Single Point Bonded Systems

The metallic sheath of a single point bonded system must only be connected to earth at one point. This will normally be at the termination but some systems may have the earth connection at the mid point.

Prior to commissioning the sheath connection to earth shall be verified either visually or by the use of a suitable megger.

If the sheath is inadvertently earthed at more than one point any load current in the circuit will establish circulating currents in the sheath. To ensure that this is not the case, when the circuit is first placed on load a tong ammeter shall be used to ensure that there is no current in the sheath earth strap.

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(d) Contact Resistances

The contact resistance of all earthing and sheath bonding connections shall be measured using a calibrated digital micro-ohmmeter.

The contact resistance between each lug attached to the joint sleeve of a sectionalised joint and the corresponding bonding lead connector shall be measured prior to the fitting of the outer protective cover.

The contact resistance shall not exceed the following:-

Contact Maximum Contact Resistance (μΩ)

Link Contact 20

SVL Terminal Connection 50

Join Lug and Bonding Connector 20

Earth Connection 50

(e) Insulation A.C. Voltage Withstand Test

The cable shall withstand an a.c. test voltage applied between the conductor and sheath, with the sheath earthed. The test voltage will normally be provided by a resonant test set operating close to power frequency. The requirements of the test are summarised below. No breakdown of the insulation shall occur.

System Voltage ( kV) Site Test Voltage ( kV) Frequency (Hz) Duration (h)

132 2.0.U0 30-300 1

33 2.0.U0 30-300 1

11 2.0 U0 1

(f) Oversheath D.C. Voltage Withstand Test

The cable oversheath shall be subject to a D.C. voltage test as specified in IEC 60229 This requires a direct voltage of 4 kV/mm of specified thickness up to a maximum of 10 kV with the sheath as the negative electrode. For 132 kV cables the oversheath thickness will be taken as the nominal value.

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15.7.19.5 Cable Sealing Ends Type, routine, sample and special tests shall be carried out in accordance with IEC 60137, where applicable, and the Schedules. Type tests shall be made on an external insulator which has passed its routine tests.

15.7.20 LV Cables 15.7.20.1 Type Tests Type tests shall be shown to have been performed on each type and rating of the specified equipment with purpose of proving its properties.

The following type tests shall be performed:

(a) Partial discharge test at room temperature.

(b) Bending test followed by partial discharge test.

(c) Measurement of power factor depending on temperature.

(d) Measurement of insulation resistance at room temperature and service temperature.

(e) Impulse voltage withstand test.

(a) Dielectric test by DC voltage preferably.

15.7.20.2 Routine Tests Routine test shall be performed at each item of equipment to be supplied for the purpose of revealing faults in material or construction. They shall not impair the properties and reliability of a test object or reduce its lifetime.

The following routine tests shall be performed on all lengths of cables and all accessories to be supplied:

(a) Conductor resistance

The dc resistance of the conductors shall be measured by an approved method and shall not be greater than the figure stated in the Schedules when adjusted for temperature.

(b) Voltage test

The voltage test shall be made with alternating current of approximately sine wave form at any frequency between 40-62 Hz inclusive. The voltage shall be increased gradually and maintained continuously for one minute at 5 kV ac rms between each conductor and the remaining conductors connected to the armour and earthed. No breakdown of the insulation shall occur.

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(c) Insulation resistance

The insulation resistance shall be measured between each conductor and the other conductors connected to the armour. After the application of 500 V dc for one minute, the measured value shall not be less than the figure stated in the Schedules when adjusted for temperature.

(d) Electrical tests on extruded PVC oversheath

Extruded PVC oversheaths shall be spark tested in the manner described in Clause 16.2 of BS 6346.

(e) Mutual capacitance

The mutual capacitance of multipair cable shall be measured between the two conductors of each pair with the other conductors and armour earthed. The measurements shall be made using alternating current and a suitable bridge and the mean value obtained shall be recorded.

(f) Bending test

A sample of each completed cable shall be subjected to a bending test as specified in Clause 31 of BS 6480, the test cylinder diameter being not less than eight times the overall diameter of the cable. After test a 300 mm length cut from the middle of the sample shall be stripped and examined.

15.7.20.3 Site Tests On arrival at site, during installation and after complete installation, all items of equipment shall be inspected and tested in order to check quality, correct operation and correct installation of the equipment.

The following tests shall be performed:

(a) General inspection of the cable routes, verification of proper installation, fixing to the racks, bending radius, etc

(b) Verification of proper earthing of the screen and armouring

(c) Measurement of cables insulation resistance

(d) Verification of proper condition of external surfaces

(e) High voltage test

Each completed circuit shall be tested for 15 minutes at a dc voltage of 4 Uo or an ac voltage of U applied between the conductor and the sheath or metallic screen without failure.

(f) Conductor resistance test

The dc conductor resistance of each completed circuit shall be measured and recorded. When corrected to 20°C by means of the temperature correction factors in Appendix 2 it shall not be greater than the figure stated in the Schedules.

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(g) Cable covering protection units (CCPU).

The CCPU shall be voltage tested on site and the current/voltage characteristics shall be recorded and shall be within the values given in the Schedules.

On completion of the above test the CCPU shall be isolated from each and the resistance between the CCPU and earthed metal shall not be less than 10 megohms when measured with a 1000 V Megger.

(h) Testing of link boxes and links

Link connections shall be capable of withstanding an impulse of 35 kV peak between links and 17.5 kV peak between links and earth.

(j) Voltage test on outer covering

(i) After laying each drum length, the cable shall withstand a voltage of 10 kV dc or 5 kV ac applied for one minute between the screen or metallic sheath and the external conducting surface.

(ii) After completion of the installation of each circuit the cable shall withstand a voltage of 5 kV dc applied for one minute between the screen or metallic sheath and the external conducting surface.

(k) Capacitance test

Each complete cable shall be listed for capacitance to earth of each core which shall not be greater than the figure stated in the Schedules.

15.7.21 Motors and Motor Control Equipment Motor performance tests shall be in accordance with IEC 60034-1. Motor control equipment type and routine tests shall be carried out in accordance with IEC 60947-4-1.

15.7.22 Material Where required, selected Type tests shall be performed on samples from metals used in the contract works. They shall be tested to prove compliance with the specification including the stated guarantees.

15.7.23 Galvanizing Selected samples of all galvanized material shall be subjected to the galvanizing tests set out in BS EN 10244-2 (Testing of Zinc Coating on Galvanized Wires) or BS EN ISO 1461 (Testing of Zinc Coating on Galvanized Articles other than Wire) whichever is applicable.

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15.7.24 Line Traps 15.7.24.1 Type Tests Line traps shall be subject to type tests in accordance with IEC 60353.

The power line carrier equipment cubicles shall be subject to type tests to verify the performance parameters and characteristics required by the specifications. In particular reference is made to the following:-

(a) Where the carrier is specified for use with protection signalling, it shall be proved that the system will be substantially free from mal-operation under power system disturbance conditions.

(b) Where the carrier system is specified for use with supervisory control and telemetering, its suitability for this purpose at the signalling speeds concerned shall be verified. Measurements of differential delay distortion may be required.

15.7.24.2 Routine Tests Line traps shall be subject to routine tests in accordance with IEC 60353, together with verification of the tuning device and protective characteristics.

The capacitance and power factor of the coupling capacitor shall be measured, and the dielectric tests shall be carried out on the coupling capacitor.

The characteristics of the line matching units and coupling filters shall be verified, and dielectric tests shall be carried out on these items.

The power line carrier equipment cubicles shall be subject to routine tests in accordance with the manufacturers works programme of tests. The following shall be included in the range of tests to be applied: -

(a) Insulation tests on output relays and circuits connected with the low voltage a.c. and d.c. auxiliary supply systems.

(b) Tests on power supply stability over the permitted range of input supply voltage variation.

(c) Nominal level of signals throughout the equipment.

(d) Range of audio input and output levels.

(e) Response characteristics audio/audio, audio/sideband and sideband/audio.

(f) Inherent signal/noise ratio and distortion factor.

(g) Functioning of automatic gain control.

(h) Functioning of emergency telephone

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15.7.25 Control and Indicating Panels, Instruments and Secondary Wiring 15.7.25.1 Type Tests (a) Mimic diagram panel operation tests.

One typical indicating panel shall be erected as in service and the indicating devices operated to the satisfaction of the Engineer.

15.7.25.2 Routine Tests All panels and instruments shall comply with the tests specified in the appropriate standard Specifications.

The wiring on each panel, cubicle, rack and each removable panel or plate of apparatus shall be subjected for one minute to an alternating voltage equal to the test pressure specified for the apparatus to which it is connected. This test shall take place after the complete assembly of the apparatus and wiring on or in the panels, cubicles and racks.

All wiring and apparatus which is, or may become, connected to voltage sources other than the supply for the very low voltage (50 volts and below) apparatus shall be subjected for one minute to an alternating test pressure of 2 000 volts rms to the frame of the panels on which they are accommodated, immediately after which the insulation measured at 6 500 volts dc shall not be less than 20 megohms. Included in these requirements is apparatus and wiring which become connected to voltage or current transformers.

The windings and electrical connections of indicating and recording meters shall be subjected for one minute to a test voltage of 2 000 volts rms to the case or any other metal which is not intended to be insulated from the case when the instrument or meter is in use.

15.7.26 Protection Equipment 15.7.26.1 Routine Tests All relays shall be subjected to routine tests at the manufacturers works to confirm that they comply with the claimed performance and design limits.

For measuring relays (i.e relays which have a defined setting of the input and/or characteristic quantity subjected to accuracy requirements, e.g. current, time, etc) these routine tests shall include as a minimum the following:

(a) Measurement of the assigned error(s) under reference conditions, i.e measuring accuracy and operating time characteristics.

(b) Measurement of the resetting ratios.

(c) Dielectric tests as specified in Clause 6 of IEC Publication 60255-5, the test voltage being 2 kV rms. All normally open output contacts of all relays shall withstand a test voltage of 1 kV rms.

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For all-or-nothing relays, the routine tests shall include a check of relay operation and resetting, together with the dielectric tests described above.

Unless otherwise agreed with the Engineer, all unit protection schemes using either biased differential, current balance or voltage balance principles shall be subjected to heavy current conjunctive tests using the actual current transformer windings which will be used in service. Tests shall be made to prove operating sensitivity, time of operation and to demonstrate stability of the protection under the worst transient external fault conditions. Tests will only be waived if the manufacturer is able to produce type test results for an identical scheme. In this case it will be sufficient to prove that individual component characteristics are identical, e.g. current transformers are of the same design, have the same magnetisation characteristics, knee-point voltage and secondary resistance.

For protection schemes including distance protection, phase comparison protection, auto reclosing and automatic switching sequence schemes, etc routine tests shall be performed on each complete scheme to ensure that all possible operational sequences and features are fully functional. Where necessary, this shall be done using simulation of any ancillary equipment normally used in conjunction with the scheme, e.g. circuit breakers. These routine tests will be performed in addition to the tests normally applied to individual elements of the scheme and details of the proposed test programme shall be submitted to the Engineer for approval not less than one month before they are to be performed.

If such routine tests are not practicable due to the complexity of the scheme, a scheme type test will be accepted on representative production equipment. The test shall be performed so as to simulate, as nearly as possible, the conditions which will be experienced in service and details of the proposed test programme shall be submitted to the Engineer for approval not less than one month before they are performed. In those cases where correct operation of the scheme is dependent on measured quantities associated with primary system plant (e.g. circuit breaker gas pressure), such quantities shall be measured directly during the tests.

Each circulating current protection scheme designed in accordance with Appendix 4 must fulfil the following routine testing requirements:

(a) Each current transformer, which must be of the low reactance type, shall be individually tested for turns ratio, secondary winding resistance and excitation characteristic up to a secondary voltage equal to 120 per cent of the "knee-point" voltage.

(b) The VA consumption at operation of current operated relays shall be measured and shall not exceed the maximum value declared by the manufacturer.

(c) The operating current of voltage relays shall be measured and shall not exceed the maximum value declared by the manufacturer.

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15.7.26.2 Type Tests Approved type tests shall be carried out in the manufacturer’s works on each type of protection system. During the tests, ancillary equipment shall be erected and connected so as to reproduce service conditions as closely as possible. The main purpose of these tests shall be to determine the performance of the protection for the range of system conditions which will be encountered by the protection in practice, and to determine all the appropriate application parameters. The test condition shall be as agreed by the Engineer.

Where type tests have been carried out under previous contracts on protective equipment similar in all essential respects to the equipment included in the Contract, the Engineer may waive the type tests on production of complete test records which he approves, relating to the equipment concerned. Each set of test records shall include a full statement of the performance claims, e.g. performance under reference conditions, effect of influencing the quantities, steady state and dynamic stability for unit protection schemes, current and voltage transformer requirements, etc and full details of tests performed on representative samples of production equipment to demonstrate that the performance claims have been met.

15.7.27 Batteries and Associated Equipment 15.7.27.1 Battery Charger (a) Constant voltage chargers

Tests shall be carried out to show that the output voltage remains constant with any combination of the input voltage, frequency and load variations stated in the Schedules and the output voltage on each voltage tap shall be measured at rated load and frequency.

The efficiency shall be measured at normal output voltage and current and normal input voltage and frequency.

Tests shall be made to prove that the insulation resistance of the transformer complies with this Specification.

The output terminals of the charger shall be short circuited and the output current measured. This shall not be greater than the value given in the Schedules.

In the case of 50 volt battery chargers only, tests shall be made to show that the psophometric noise level specified is not exceeded and for this purpose the following notes shall be observed:-

(i) For floated battery systems, it is necessary to keep any noise introduced by the charging device to an acceptable level for communication purposes. The maximum permitted noise level from all sources for commercial telephone circuits in cable is the equivalent of 2 mV at 800 Hz (rms value). Neither the average human ear nor telephone receivers in common use respond equally at all frequencies, the response being less above and

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below a narrow band of frequencies, around 800 Hz. A given disturbing voltage at frequencies outside this band therefore represents a lower noise level than such a voltage at 800 Hz. A correction factor is applied to obtain the equivalent in terms of 800 Hz noise. This correction factor is the "weighting" assigned to each frequency in the CCIF table, a copy of which is included as Appendix 5. By definition the psophometric noise is

1/800 * Pf2 * Vf2 where Pf is the weighting factor

and Vf is the voltage at different frequencies.

(ii) To obtain a result with one measurement only a psophometer must be used incorporating a weighting network. It is not possible to state the noise level from a measurement at one frequency only even if this is the fundamental ripple frequency, nor is it possible to measure the aggregate noise level without a suitable weighting network. Statements of ripple voltage in the form of a percentage are valueless. It will be noted that the maximum acceptable noise level for the battery and charger is that recommended for commercial telephone circuits in cable and apparently leaves no margin for other sources of noise. Battery potentials are not applied directly to telephone circuits, however, and in practice the adoption of the same standard for the battery and charger as for a telephone line provides an adequate margin and permits the charger smoothing equipment to be to commercial standards.

(iii) The maximum permissible noise level is specified with the battery connected in circuit. The battery provides a low impedance path for the ac currents involved. When acceptance tests are made on a charger otherwise in situ with its associated battery, the resistance of the test battery may be measured and a correction factor applied. The tests should always be made with a fully charged battery. There is, however, variation of battery resistance with temperature and state of charge, even though the battery appears to be fully charged. In order to obtain a uniform standard the noise measurements should be corrected by the percentage by which the battery resistance differs from the following figures: -

Normal Size Battery DC Resistance AC Resistance of charger Capacity in ohms in ohms 5 A 40 Ah 0.11 0.05 5 A 50 Ah 0.11 0.05 10 A 75 Ah 0.06 0.03 15 A 100 Ah 0.06 0.03 15 A 150 Ah 0.04 0.02 20 A 200 Ah 0.03 0.02 25 A 250 Ah 0.03 0.02 50 A 300 Ah 0.02 0.01

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As it is unreasonable to expect a full range of batteries at a Contractor's works, chargers may be tested with a battery within this range, the necessary correction factor being applied in accordance with the table above, it being assumed that the charger is to work with a battery for which it is the normal size. The battery used must be in good condition and comply with BS 6290. Connections between charger and battery and load and battery must be taken back separately to the test battery and the connections must be adequate.

(b) Boost chargers

Tests shall be carried out to prove compliance with the particulars given in the Schedules.

Tests shall be made to prove that the insulation resistance of the transformer complies with this Specification.

15.7.28 Low Voltage Switchboards Type and routine tests shall be performed in accordance with IEC 60439. All individual components contained in the switchboard shall be tested in accordance with the relevant part of this Specification.

15.7.29 Capacitor Banks 15.7.29.1 General Where type tests are required on capacitors, these shall, unless otherwise specified, be taken pro-rata to the number of units (as indicated below) of each different type on the Contract; units for type tests shall be selected from those items which have already passed any required routine and sample tests.

The number of units to be selected for type tests shall be determined as follows:-

For up to 50 unit capacitors to be installed - one unit capacitor,

For over 50 units capacitors to be installed - two unit capacitors.

Where sample tests are required, these shall, unless otherwise specified, be taken on at least two per cent (with a minimum of two) of each type of the Contract and shall be samples from those items which have already passed the routine tests. The samples shall be selected by the Engineer at random from the batch of batches submitted. In the event of any failure during the tests a further two per cent (with a minimum of two) shall be selected by the Engineer and submitted to such repeat sample tests as may be required. In the event of any failure during these tests, the whole of the batch or batches from which the selection was made, may, at the discretion of the Engineer, be rejected.

The complete unit capacitors subjected to the type tests shall first have satisfactorily withstood all the routine tests.

Complete unit capacitors and insulators which have been subjected to sample or type tests shall not be incorporated in the capacitors delivered to Site.

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15.7.29.2 Routine tests on unit capacitors The routine tests on each unit capacitor shall be in accordance with IEC 60871 with the addition of the following test:-

(a) Stability of characteristic or discharge test

The unit capacitor shall be tested as follows:

Measure the capacitance and tan delta of each unit at 10 per cent and 100 per cent of rated voltage (Un) before and after the application of the routine voltage withstand test. After correcting the results to 20°C the capacitance variation shall not exceed two per cent.

Note: If the manufacturer chooses to make a suitable discharge tests, this would be preferred to a substitute for the test detailed above. The form, method of measurement, and acceptance of such a test will be subject to agreement between the Contractor and the Engineer.

15.7.29.3 Sample tests on unit capacitors The following tests shall be carried out on unit capacitors selected by the Engineer at random from those which have already satisfactorily withstood routine tests. The size of sample shall be at least one unit capacitor selected from each and every batch of unit capacitors impregnated.

(a) Power factor/voltage test

The unenergised capacitor shall be held in an ambient temperature of 70°C until thermal equilibrium is established and the power factor then determined at 50 Hz and, if possible, for a range of voltages up to or exceeding the Ut which is equal to 2.15 times rated voltage Un. If this is not possible then measurements should be made at as high a voltage as possible consistent with the time of application of the voltage needed to achieve a power factor measurement.

The values of power factor obtained shall be plotted against the corresponding values of the voltage. Similar curves may be required at other temperatures in particular at -10°C and +45°C. The co-efficient of change of capacitance over this temperature range will also be required.

(b) Partial discharge test

The sample will be chosen to be best representative of all the batches processed. The procedure will be as follows:-

(i) The containers of the selected units will be opened alternatively at the top and bottom to expose a row of capacitor elements. Discharge tests will be made on pairs of elements at the two ends and middle of a row. Thus three discharge tests per container will be made as follows:

- The voltage shall be raised to 3 Un momentarily, reduced to 1.2 Un and maintained for 10 minutes, raised to 1.5 Un and held for 10 minutes, the discharge

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measurement made at 1.5 Un shall not exceed 5pC, and shall not increase with time during this 10 minute period.

- The partial discharge levels will be recorded, including the discharge inception and extinction voltages.

- Any units which fail the overvoltage test may be included in this sample. If a discharge test is unsatisfactory on elements in a unit which has failed the overvoltage test, then as a substitute, an extra unit which has passed the overvoltage test may be opened and discharge tests made on elements at either the top or the bottom.

The method of partial discharge detection and measurement shall be to the approval of the Engineer.

(c) Breakdown voltage tests

A breakdown test will be made on the elements tests in items (a) and (b) above. The voltage at which failure occurs shall be recorded.

A voltage of ½ Un shall be applied and raised in equal steps of 10 per cent of the initial value until breakdown occurs each step being applied for 60 seconds. The temperature shall be between 15°C and 40°C.

15.7.29.4 Type Tests on Unit Capacitors Type tests shall be carried out in accordance with IEC 60871. The unit capacitors selected for the thermal stability tests shall be typical of those unit capacitors having the highest watt-loss permitted by the manufacturer's test limits.

In addition to the thermal stability test described in IEC 60871 the Engineer may require tests to his approval to demonstrate thermal stability at all ambient temperatures ranging from the maximum value of 40°C determined from the foregoing test down to -10°C.

Tests on internal fuses shall be performed in accordance with IEC 60871. The method to be adopted for carrying out these tests shall be approved by the Engineer and must be such that the test demonstrates that the internal fuse arrangement provides for the isolation of a faulty element or group of elements, thus enabling the capacitor to be kept in service pending the breakdown of further elements.

Furthermore, the test should also demonstrate that the contamination of the Impregnate due to the blowing of internal fuses will not affect the performance of the healthy elements.

15.7.29.5 Routine Tests on Complete Capacitor Bank The routine tests on the complete capacitor banks shall be in accordance with IEC 60871.

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15.7.29.6 Mounting Insulators for Racks of Unit Capacitors (a) Routine overvoltage tests

The complete mounting insulator unit, clean and dry, shall withstand for five minutes without puncturing or other damage, the routine electrical (flashover) test prescribed in IEC 60137.

(b) Type tests

The following type tests shall be carried out on three complete mounting insulators representative of each type. The units comprising the mounting insulators shall be selected by the Engineer from those which have already passed the routine test.

For the purpose of the type tests, a one metre length of conductor not more than 50 mm diameter shall be mounted horizontally and directly on the cap of the top insulator unit and the mounting insulator shall be set upright on a circular metal plate not less than one metre in diameter and so arranged that the distance between the conductor and the ground is not less than one-and-a-half times the height of the mounting insulator. The results the tests shall be corrected for temperature, barometric pressure and humidity in accordance with Appendix A of IEC 60137, and the corrected flashover values shall be not less than those stated in Schedule D. The records of the tests shall include sufficient manufacturing drawings to identify the type of insulator completely.

(i) Dry flashover type test. Each complete mounting insulator, clean and dry and without arcing horns or rings other than those essential for stress control, shall be set up as described above. A voltage of about one-half of the full test voltage shall be applied and shall be increased steadily to approximately 90 per cent of the estimated flashover value, and thereafter at a rate of not more than 5 kV per second until flashover occurs. The test shall be repeated and the flashover voltages shall be taken as the mean of at least five consecutive observations.

(ii) Impulse flashover type test. If required by the Engineer, each selected insulator set up as for the dry flashover test above, shall be subjected to a dry impulse 50 per cent flashover test as prescribed in IEC 60137.

15.7.30 Series reactors Type and routine tests on series reactors are to be in accordance with IEC 60289.

15.7.31 11 kV Metal Clad Switchgear Inspection & Testing

Type and routine tests shall be carried out strictly in accordance with IEC 62271-200, IEC 60694, IEC 62271-100, IEC 60427, IEC 60060, IEC 60270, IEC 62771-110 and any other relevant standards and requirements of this Specification where appropriate.

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Type Tests

Inspection & Testing

Type tests shall have been witnessed by an independent third Party.

The following type tests shall be performed:

(a) Dielectric test on main circuit - Lightning impulse, Power frequency voltage withstand tests, Partial discharge and Radio interference voltage (r.i.v) tests

(b) Dielectric test on auxiliary and control circuit

(c) Temperature rise test

(d) Measurement of the resistance of the main circuit

(e) Short-time and peak withstand current tests

(f) Short-circuit making and breaking, out-of-phase making and breaking, critical current and capacitive and inductive (reactor) current switching tests

(g) Internal arcing test

(h) Mechanical endurance, environmental operation tests

(j) Electromagnetic compatibility (EMC) tests

(k) Verification of the degree of protection and tightness tests

(m) Any other tests in accordance with the above standard

Capacitive Current Switching Tests

The capacitive current switching duty specified in the Schedules for the circuit breaker shall be tested in accordance with IEC 62271-100. Test evidence shall be submitted to confirm that the highest over voltage during any switching duty does not exceed 2.5 p.u. by either performing the relevant tests or by submitting the relevant type test reports to the satisfaction of the Ministry of Electricity.

Low Inductive Current Switching Tests

A series of switching tests shall be made to IEC 62771-110 on each type of circuit breaker being supplied in order to demonstrate its performance when switching transformer magnetising currents and reactor currents. Test evidence shall be submitted to confirm that the highest over voltage during any switching duty does not exceed 2.5 p.u. by either performing the relevant tests or by submitting the relevant type test reports to the satisfaction of the Ministry of Electricity.

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In addition to the above, additional, low inductive current switching test evidence of 10, 50, 100 amp currents, in accordance with IEC 62771-110 under site conditions, to confirm that the highest over voltage during any switching duty does not exceed 2.5 p.u.

Internal Arcing Tests

Internal arcing tests shall be carried out in accordance with IEC 60298 - Annex AA. The test evidence for each compartment shall confirm that the equipment satisfies the IEC test criteria that the internal arcing fault in one compartment does not affect the adjacent compartments and in particular the relay compartment.

Routine Tests

The following routine tests shall be performed:

(a) Dielectric test on the main circuit - Dry power frequency voltage withstand, Partial discharge and Radio interference voltage (r.i.v) tests




(e) Pressure and Gas tightness tests

(f) Design and visual checks

(g) Inspection of the general condition

(h) Timing tests of the main contacts and auxiliary switches

(j) Complete electrical functioning tests

(k) Closing and opening check at reduced voltage and other necessary tests and verifications

Site Tests

As a minimum, the following tests after installation on site shall be performed:

(a) Power frequency voltage tests on the main circuits

(b) Dielectric tests on auxiliary circuits


(d) Gas tightness tests

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(e) Design and visual checks

(f) Measurement of gas condition

(a) Mechanical operation tests

(b) Secondary injection tests on all protection relays

(c) Primary inject tests on all protection relays and associated current transformer circuits

(j) Complete electrical functioning tests including the function of all interlocks

15.7.32 GIS Building Crane All parts of the GIS building crane shall be tested in accordance with the appropriate IEC or other standards to the approval of the Engineer.

15.7.33 Fire Protection Equipment All parts of the fire alarm system, fire extinguishers and transformer fire protection system shall be tested in accordance with the appropriate IEC or other standards to the approval of the Engineer.

15.7.34 Substation Control System 15.7.34.1 Approach to Testing The testing philosophy for the SCS shall ensure that the equipment functionality and site specific facilities are thoroughly exercised and validated at the Contractor's premises before delivery, and that the site specific facilities are confirmed during commissioning. The test methodology shall complement the design methodology and the two shall be developed in parallel.

This document does not constitute a Test Specification or Test Procedure for any part of the system, rather it sets out the stages at which tests are required and the subjects, location and purpose of each stage. All Test Documentation for all tests shall be written by the Contractor and submitted to the Engineer for approval at least 12 weeks before they are first used.

Where any equipment is not connected to the SCS, but has its facilities marshalled in the marshalling cabinet, these connections shall be included in the testing regime.

The confidence testing of the operation of the substation plant from the NCC SCADA system via the SCS and other control and monitoring from the Substation SCS and the NCC is included in the Works. The equipment shall be entirely compatible with the communications protocols as may be required by the NCC and with the communications media available. The Contractor shall undertake specific testing to demonstrate the compatibility of the SCS with the NCC.

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15.7.34.2 Testing Stages The SCS shall be subject to acceptance testing as specified in this document. The stages of testing to be performed at higher levels shall be based on the following:

(a) Factory Acceptance Testing (FAT)

To check that the totality of the equipment supplied under the Contract performs in accordance with the Contract requirements.

Factory Acceptance Testing (FAT) shall be performed with the SCS assembled at the factory as a complete system. The FAT shall exercise and prove the correct operation of all functions of the supplied SCS whether used in this project (as supplied) or not, and the site specific facilities, using simulation where necessary, including the interface for connection to the National Control Centre SCADA system. The Tenderer shall state how they would undertake the FAT of the SCS in their offer.

(b) Site Acceptance Testing (SAT)

To check that the totality of the equipment supplied under the Contract performs in accordance with the Contract requirements and interacts correctly with equipment supplied by others and interfaces correctly to the Works.

Site Acceptance Testing (SAT) shall be performed with the complete SCS installed on site with all interfaces to the substation plant connected and functional and be conducted after the successful completion of the Contractor’s own testing of the system. The SAT shall exercise and prove the correct operation of the functions of the supplied SCS used in this project, including all the testing of all facilities between the National Control Centre and SCS. The Tenderer shall state how they would undertake the SAT of the SCS in their offer.

(c) 500 Hour Trial Period (following System SAT)

'Hands on' test period to demonstrate the reliability, stability and robustness of the SCS.

15.7.34.3 Notice & Witnessing of Tests The Contractor shall provide, as part of the Programme of Work documentation, a master plan showing the scheduled dates of testing and shall provide updates to this plan, when any changes are known, at least 6 weeks in advance of the tests.

The Contractor shall advise the Engineer in writing of the actual date of commencement of every test at least 10 working days before the commencement.

The Engineer shall have the right to witness any tests whether conducted at the Contractor's premises or elsewhere. Records of every test, whether witnessed or not, shall be taken by the Contractor and copies sent to the Engineer within 3 weeks of completion of the tests.

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15.7.34.4 Test Procedures and Result Sheets The Contractor shall prepare test procedures and result sheets for all tests. The Contractor shall also prepare a cross reference listing to show that all of the requirements of the Functional Design Specification have been included in the tests.

Separate test procedures and result sheets shall be provided for factory and site acceptance tests. All test procedures and result sheets will be subject to review and approval by the Engineer.

Test result sheets will be retained as part of the permanent QA record for the SCS.

15.7.34.5 Contractor’s Prior Tests The Contractor shall successfully complete a prior run of all tests, using the test procedures and result sheets described above, before the commencement of the formal tests.

Any revisions to the test documents found necessary as a result of the prior tests shall be made before the commencement of formal tests.

Test results from the prior tests shall be made available to the Engineer, on request, to indicate the readiness of the equipment for testing to commence.

15.7.34.6 Fault Categories The Engineer will allocate a category to each fault, which shall determine the future tests required. Test categories shall be as defined in the Table at the end of this section.

15.7.34.7 Repeat Tests The Contractor shall correct and re-test every fault detected during the tests.

15.7.34.8 Fault Log The Contractor shall maintain a fault log throughout each series of tests. Every fault detected during the tests will be entered in the log, together with the actions taken to clear and re-test the fault.

The fault log will be retained as part of the permanent QA record for the SCS.

15.7.34.9 Hardware Failure Reports For each hardware failure that occurs at any stage of testing, the Contractor shall investigate the failure and prepare a report on its cause(s) and design implications. The report shall clearly show:

(a) the most likely cause of the failure

(b) an analysis of any stress that may have been caused to other components of the equipment being tested as a result of the failure

(c) whether the failure is a result of any component operating outside its design range

(d) whether any design changes should be made to avoid further failures.

All such reports will be retained as part of the permanent QA record for the SCS.

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15.7.34.10 Software Failure Reports For each software failure that occurs, once the software has been approved for inclusion into the system and is subject to configuration control, the Contractor shall generate a software failure report. The report shall clearly show:

(a) The observed symptoms

(b) The likely cause

(c) The fault category

The report shall also clearly show the following information, which shall be entered when the failure has been investigated:

(a) The actual cause of the failure

(b) The corrective action taken

(c) All software modules affected.

All such reports will be retained as part of the permanent QA record for the SCS.

Table -1 Fault Categories

Category Definition

0 An item recorded as a fault during testing, and subsequently considered to be a normal acceptable occurrence. Testing may continue.

1 Minor fault. An event not affecting the functionality being tested in that session. Testing may continue.

2 Repeatable fault not affecting the functionality being tested in the session. Testing may continue at the discretion of the Engineer.

3 Repeatable fault affecting the functionality being tested in the session. The fault must be rectified before re-test of the affected test session. Testing may proceed on other sessions if permitted by the Engineer.

4 Major fault affecting the functionality being tested in the session. The fault must be rectified before recommencing testing.

5 Non-repeatable fault affecting functionality being tested in the session. The action taken will depend on the severity of the fault. Discussion is needed to establish the most appropriate course of action.

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Category Definition

6 Documentation error or deficiency. The error will usually be amended during the test and the test will continue. The documentation shall be corrected before the tests are considered complete.

7 Deficiency in the ability of the test or test equipment to demonstrate the function being tested in the session. Discussion is needed to establish the most appropriate action, which will usually result in a more appropriate test being devised, by the Contractor and the function re-tested using that new test. The test documentation shall be updated to include the new test procedure.

8 Other fault not covered above, but requiring explanation and, in some cases, correction.

15.8 Site Testing and Commissioning

15.8.1 Extent of Supply The scope of the commissioning programme will include the testing of:

(a) All 132 kV and allied 33/11 kV primary plant, such as switchgear, buswork, instrument transformers and the necessary interface with the existing system or equipment supplied by others:

(b) Indicating meters, relays control and communications equipment and similar functions associated with the primary plant, including the necessary interface with existing installations or equipment supplied by others:

(c) Station auxiliaries associated with (a) and (b) preceding, and including such items as fans, compressors, lights, batteries and allied chargers and air conditioners:

(d) All energy meters will be tested and certified by MOE.

15.8.2 General The Contractor shall be responsible for the commissioning of all equipment covered under the Contract and also be responsible for the successful interface of the equipment with existing facilities and/or equipment supplied by others.

The Engineer shall have the right to witness all tests, and the results must be available to him as the tests proceed. He may recommend waiving of some tests, or may add further tests if considered necessary to prove compliance with the Specification.

The Contractor shall prepare and submit three months prior to the start of commissioning detailed commissioning and testing procedures for approval by the Engineer.

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Some equipment specific site test requirements are stated in the “Specific Equipment Tests” clause, above.

15.8.3 Objectives (a) The objectives of commissioning work prior to energisation of plant at full voltage or connection

to system include:

(i) integrity (correctness) of installation and confirmation that equipment has not deteriorated since the completion of the Factory Acceptance Tests;.

(ii) integrity of insulation, connections and phasing;

(iii) proof of equipment characteristics;

(iv) review of workmanship;

(v) review of applications engineering and equipment ratings (final field check on design).

(b) The objectives during and following equipment energisation or connection to system include:

(i) performance checks on the various manual and automatic control features;

(ii) ability of the system to accommodate scheduled or unscheduled connection and disconnection of plant without undue disturbance;

(iii) loading and performance tests on primary components (and possibly including verification of losses in some cases);

(iv) integrated system performance tests;

(v) corona and RI tests.

15.8.4 Responsibilities The Contractor shall be responsible for all testing in preparation for first energisation or connection to system, with possible constraints imposed by MOE operating staff because of safety or other considerations.

MOE shall retain responsibility for the connection and disconnection of primary equipment to and from system, including first energisation of new equipment, but with the advice and technical assistance of the Contractor.

The Contractor shall be responsible for all testing with the equipment connected to the system, but within the constraints which may be imposed by MOE as a result of the then existing operating configuration. Equipment being so tested will not be classed as being in commercial service and the Contractor shall not be responsible for consequences to equipment on the system as a result of unscheduled operation, or tripping, or error in testing. The Contractor shall remain responsible for the performance of his equipment during the live tests.

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15.8.5 Owner Participation The Contractor shall plan for MOE staff participation either continuously or on a regularly recurring basis in the commissioning work with the primary intent of:

(a) becoming familiar with the operating and maintenance aspects of the new equipment.

(b) maintaining a continuing assessment of the precautions required in, or possible consequences of, initial energisation of equipment.

These two necessary objectives must be allowed for in the preparation of schedules.

15.8.6 Commissioning Staff The Contractor shall be responsible for supplying commissioning personnel, including skilled and unskilled labour, as required, and will be requested to submit a list giving names, experience, and proposed duration on site. Consistent with the construction schedule, staff assigned to commissioning will fulfil that duty only, to the exclusion of others, for the duration of the assignment.

15.8.7 Test Equipment and Power Supplies The Contractor shall be responsible for supplying all instruments, tools and other equipment required for testing, commissioning, and transport, and ensure that any calibration etc is maintained and documented. All such equipment shall be listed in the procedures and offered for sale in the tender document. Prices shall be listed separate to the tender price.

The Contractor shall submit a list of the type, range, and number of test instruments required.

The Contractor shall also be responsible for making available power supplies for testing in the necessary vector configuration and voltage, and current rating at the various stations.

15.8.8 Test Jurisdiction and Safety Notwithstanding any other statements in this outline, testing and commissioning work on any equipment which is energised, or which has been transferred to MOE operating jurisdiction can only be carried out under the "hold-off" and "permit-to-work" system of MOE

The Contractor shall be responsible for safety of personnel involved in commissioning and shall take all possible precautions and be fully aware of the dangers involved in testing EHV primary equipment. It is essential that any tests involving high voltage work shall be conducted by personnel specifically authorised by the Engineer for this purpose and that such persons shall be made fully aware by the Contractor of the dangers involved in the tests.

In addition to the scheduling of commissioning tests, the Contractor shall be responsible for preparing procedures for testing high voltage related equipment. After approval by the Engineer these procedures shall be adhered to for the commissioning tests and at the end of the project shall be handed over to the client along with drawings mentioned elsewhere in this specification.

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15.8.9 Equipment Repair and Replacement Major failure or damage to equipment will require either its return to the factory or assignment of a special crew to carry out repairs. It is expected, however, that for failures in metering, relaying, control, and communications equipment the commissioning staff shall be competent and willing to undertake minor repairs or even temporary redesign and reconnection to preclude delay in energisation and commercial service.

15.8.10 Test Methods The Contractor shall, through his supervisor conduct all necessary tests to commission the sub-stations. The following site tests shall be considered to represent the minimum required in addition to those specified under the appropriate IEC, B.S. or ANSI standards or the standard specification of the country of origin and the manufacturer's instructions.

(a) System Phasing

The Engineer will provide the details of electrical phasing and phase notation during the approval of the drawings.

Potential phasing sticks or potential transformers shall be used to establish correct phasing across any open switch or breaker and testing shall always be carried out with reference to a “known system voltage source” where relevant. Control room meters and interconnecting wiring shall not be used for this purpose.

(b) DC Station Services

The Contractor shall test the dc batteries and battery charger, in accordance with the manufacturer's manuals, and perform the necessary adjustments. A discharge test of the battery shall be carried out in accordance with the relevant standards..

Before dc wiring or dc equipment is energised, a 500 volt "megger" test shall be applied to wiring and cabling only.

(c) AC Station Services

The Contractor shall inspect and test all ac wiring and ac equipment to IEC standards or other approved standards and codes. When wiring and equipment standards are questionable, the Engineer's ruling shall prevail without additional charges.

Before ac wiring or ac equipment is energised, a 500 volt "megger" test shall be applied.

(d) Oil filtering Equipment (if applicable)

The Contractor shall conduct the necessary tests on oil-filtering equipment to ensure the system is free from dirt, moisture and other detrimental foreign matter, and free from all oil leaks.

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The initial circulating oil tests shall be made without the power transformers until the system is operating to the satisfaction of the Engineer. A final circulation test shall be made with the transformer included in the system but before the transformer is placed "on-load".

(e) Control Cables

The Contractor shall conduct the necessary checks and inspections to ensure all control wiring has been installed in accordance with the cable schedules and drawings. Where changes are necessary, the Contractor shall make the required changes to the appropriate drawings and advise the Engineer, and carry out re-testing of the modified facilities if applicable.

(f) Station Earthing

The Contractor shall test the station earth before final grading of the station. Test values shall be submitted to the Engineer for approval. Where suitable earthing is found to be difficult, the Contractor shall prepare a contour plan of earth resistance together with a proposal for satisfactory additions.

(g) Insulators and Bushings

The Contractor shall inspect all insulators and bushings, in position, for chips and cracks and immediately replace any which may be damaged. All insulators shall be thoroughly cleaned before field tests.

(h) Manual Operation

The Contractor shall install, align, and test all isolating switches, disconnects, earthing blades, circuit breakers and other associated equipment in accordance with the manufacturer's instructions. The torque for manual operation shall not exceed 35 kg-m (3,000 lb-in); a preferred operational torque shall be 30 kg-m (2,580 lb-in) to allow for increased resistance to movement between periods of switch maintenance.

(j) Power Operation

The Contractor shall conduct the tests and inspections in accordance with the manufacturers instructions for the satisfactory power operation of equipment from the local control kiosks. These tests shall include operations at the minimum air system pressure and/or the reduced dc battery voltage and/or the reduced ac station service voltage, as permitted by the standards of the equipment supplier.

(k) Remote Operation

The Contractor shall conduct the necessary tests to operate all remotely-controlled equipment from both the remote and local locations. These tests shall be undertaken after the control and power cabling have been checked and tested and the SCS commissioned.

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(m) Interlocks

The Contractor shall check correct operation of all interlocks, and record the findings accordingly. Any malfunction of the interlocking scheme shall be brought to the attention of the Engineer.

(n) Relay Tests

The Contractor shall undertake all necessary tests to establish the correct functioning of all protective, ancillary and auxiliary relays to the design data of each relay.

The tests shall include, but not be limited to, the following:

(i) Insulation resistance of all secondary circuits (current and voltage transformers, control, indication and alarm circuits).

(ii) Tests to check the magnetisation curve, polarity and resistance of current transformers.

(iii) Secondary injection of voltage transformer circuits.

(iv) Secondary injection of ac and dc relays to check their operating characteristics.

(v) Primary injection of current transformer circuits including overall injection of differential protection circuits to check all connections, fault settings and stability.

(vi) Sequence tests

(vii) Characteristic and accuracy tests

(viii) Calibration and settings tests

(ix) Phasing tests prior to making alive.

(x) On-load checks of protection, indicating and metering circuits.

The Contractor shall make all final relay settings to the approval of the Engineer. Final acceptance tests will be performed by the Contractor, witnessed by MOE. On completion of all tests, all relays will be sealed by MOE

(p) Transmission Line Data Measurement

To get a proper base for relay setting calculation in the substation, the Contractor shall measure line data of all the transmission lines, which are connected to the substation.

(i) Accuracy of the measurement shall be not less than ± 3%.

(ii) Positive and zero sequence resistance, reactance, and parallel susceptance shall be measured, without and with line reactors and neutral reactors if supplied.

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(iii) Direct measuring shall be applied (without P.T. and CT)

(q) Testing under Other Contracts

The Contractor shall co-ordinate the testing under this Contract with the testing by suppliers of other equipment.

15.8.11 Particular Constraints & Special Tests Possible low short circuit levels on the 132 kV system may impose constraints on switching. and restrict the response of protection or interfere with the co-ordination of 132 kV relays.

In a similar context, the following list of special tests, which may be required, is intended as representative only, and not necessarily complete:

(a) Interference tests between the earth grid and control circuits:

(b) Single-pole switching tests - with or without initiation by actual fault;

(c) Carrier transmission attenuation or interference tests during fault and live disconnect operation;

(d) Switching surge measurements.

15.8.12 Commissioning The Contractor shall place "on line" all work covered by this Contract after all tests have been satisfactorily carried out, together with work by other contractors or with existing installations. The actual scheduling of the commissioning shall be as agreed with the Engineer.

15.8.13 Test Schedule The Contractor shall prepare, for approval by the Engineer, a schedule of field testing and commissioning. The schedule shall provide sufficient time for MOE to be present to witness them. Changes and modifications to the schedule shall also be approved by the Engineer.

15.8.14 Records (a) Test Results

These shall be witnessed by the Engineer, and documented on forms to be agreed upon by the Contractor. The record shall include other pertinent data such as omissions or unsatisfactory test results. Where disagreement exists, the ruling of the Engineer shall be binding.

The Contractor shall maintain an up to date record of all inspections and tests, which shall be handed over to the Engineer at the completion of the site testing and commissioning.

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(b) "As Built" Drawings

The Contractor will be responsible for making available to MOE a minimum of two complete sets of marked up "as built" drawings before leaving the site. Contractor shall correct and reissue the original drawings as soon as possible after this.

REPUBLIC OF IRAQ MINISTRY OF ELECTRICITY STANDARD...

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