xxxx 132kV Substation Project

Transmission / Engineering & Project

Engineering & Design DivisionSouthern Operating Area

Saudi Electricity Company

Southern Operating AreaAbha, Kingdom of Saudi Arabia

asset maintenance department

REPLACEMENT OF AUXILIARY SYSTEM IN JAZAN CPS 132kv s/sReference No.Section 4.2.1.11Medium Voltage Switchgears (33 & 13.8 kV) Section 4.2.1.11

MEDIUM VOLTAGE SWITCHGEAR(33 kV & 13.8 kV)

Table of Contents

1(1) SCOPE

1(2) DEFINITIONS

3(3) CLASSIFICATION

3(4) REQUIREMENTS

15(5) MARKING

16(6) TESTING

SECTION 4.2.1.11

Medium Voltage Switchgears (33 & 13.8 kV) (1) SCOPE

This specification covers the design, testing and performance requirements for 13.8 kV, 33 kV Single Busbar Metal-Clad Switchgear and 33 kV Gas Insulated Switchgear for use by SEC-SOA in the Kingdom of Saudi Arabia.

(2) DEFINITIONS

1. METAL-CLAD SWITCHGEAR.

Switchgear assemblies with an external metal enclosure in which components are arranged in separate compartments with metal partitions, enclosure and partitions intended to be grounded.

2. ENCLOSURE.

Surrounding part of metal-enclosed switchgear used to prevent personnel from accidentally approaching live or moving parts contained therein and to protect internal equipment against external effects.

3. COMPARTMENT.

A part of metal-clad switchgear, totally enclosed except for openings necessary for interconnection, control or ventilation.

4. PARTITION.

A part of the enclosure of a compartment separating it from another compartment.

5. SHUTTER.

A part which can be moved between a position where it permits contacts of a removable part to engage fixed contacts, and a position where it becomes a part of a cover or a partition shielding the fixed contacts.

6. REMOVABLE PART.

A part which may be removed entirely from the metal-clad switchgear, even though the main circuit is live.

7. WITHDRAWABLE PART.

A removable part which can be moved to a position where it provides an isolating distance or segregation, whilst remaining mechanically related to the enclosure.

8. SERVICE POSITION (CONNECTED POSITION).

The position of a removable part when it is fully connected for its normally intended function.

9. DISCONNECTED POSITION (ISOLATED POSITION).

A position of a withdrawable part in which an isolating distance or segregation is established, the withdrawable part remaining mechanically related to the enclosure.

10. TEST POSITION.

A disconnected position in which the control circuits are connected, allowing tests of the mechanical operation of the withdrawable part.

11. REMOVED POSITION.

The position of a removable part when it is outside and mechanically separated from the enclosure.

12. GROUNDING POSITION.

A position in which the closing of a mechanical switching device causes a main circuit to be short-circuited and grounded.

13. RATED NORMAL CURRENT (OF A CIRCUIT).

The value of the current which a circuit of metal-clad switchgear is capable of carrying continuously under specified conditions of use and behaviour.

It is expressed as an r.m.s. value.

14. SHORT-TIME WITHSTAND CURRENT (OF A CIRCUIT).

The current that a circuit of metal-clad switchgear can carry during a specified short time under the prescribed conditions of use and behaviour.

It is expressed as an r.m.s. value.

15. PEAK WITHSTAND CURRENT (OF A CIRCUIT).

The value of peak current that a circuit of metal-clad switchgear can withstand under the prescribed conditions of use and behaviour.

16. AMBIENT AIR TEMPERATURE (OF METAL-ENCLOSED SWITCHGEAR).

The temperature, determined under prescribed conditions, of the air surrounding the external enclosure of the metal-clad switchgear.

17. MAIN CIRCUIT (OF A METAL-CLAD SWITCHGEAR ASSEMBLY).

All the conducting parts of the metal-clad switchgear assembly included in the circuits which its switching devices are designed to close or open, or which are connected to these circuits.

18. AUXILIARY CIRCUIT (OF A METAL-CLAD SWITCHGEAR ASSEMBLY).

All the conducting parts of the metal-clad switchgear assembly intended to be connected to its control, measuring, protective and regulating equipment.

19. TRANSACTOR.

A magnetic device with an air-gapped core having an input winding which is energised with an alternating current and having an output winding which produces a voltage that it a function of the input current.

Note: The term 'transactor' is a contraction of the words 'transformer' and 'reactor'.

20. IDMT.

Inverse definite minimum time overcurrent protection.

(3) CLASSIFICATION

The switchgear covered by this specification is classified as follows:

Factory assembled, metal-clad switchgear for indoor installations for rated voltages 13.8 kV and 33 kV (Single Busbar).

Factory assembled, gas insulated switchgear (GIS) for indoor installation for rated voltages 13.8 and 33 kV (Single Busbar).

(4) REQUIREMENTS

1. Service Conditions

The service conditions as shown in Section 3 shall apply.

2. System Parameters.

2.1. 33 kV & 13.8 kV Systems.

The system parameters listed in Section 3 shall apply.

2.2. Low Voltage Systems

The low voltage systems is 220/127V, 4 wire, both with multiple grounding of neutrals.

3. Applicable Codes & StandardsAll equipment provided under this specification shall conform to the latest revisions or editions of the following codes and standards:

IEC - International Electrotechnical Commission.

IEC 51-Direct Acting Analogue Electrical Measuring Instruments And Their Accessories.

IEC 56-High Voltage Alternating Current Circuit Breakers.

IEC 73-Colours Of Indicator Lights And Push-Buttons.

IEC 129-Alternating Current Disconnectors (Isolators) And Grounding Switches.

IEC 185-Current Transformers.

IEC 186-Voltage Transformers.

IEC 255-Electrical Relays.

IEC 298-Ac Metal Enclosed Switchgear And Control Gear For Rated Voltages Above 1 kV And Up To And Including 72.5 kV.

IEC 337-Control Switches.

IEC 529-Classification Of Degrees Of Protection Provided By Enclosures.

IEC 694-Common Clauses For High Voltage Switchgear And Control Gear Standards.

BSI - British Standards Institution.

BS 3938 - Current Transformers.

DIN - Deutsches Institut fur Normung e.v.

RAL Colour Codes.

VDE - Verrinigte Deutscher Elektrotechniker e.g.

VDE 0670 Part 1.

4. Design.

4.1. General Description.

The switchgear furnished under this Specification shall be of the following type:

SYMBOL 183 \f "Symbol" \s 11 \hMetal-Clad.

SYMBOL 183 \f "Symbol" \s 11 \hSingle Busbar.

SYMBOL 183 \f "Symbol" \s 11 \hWithdrawable type of modular design, similar modules being standardised and interchangeable.

SYMBOL 183 \f "Symbol" \s 11 \hVacuum or SF6 circuit breakers.

SYMBOL 183 \f "Symbol" \s 11 \hAir-insulated or SF6 insulated.

Design and construction of the equipment shall be in accordance with IEC 298 unless otherwise specified.

The equipment shall be supplied complete and ready for installation unless otherwise specified, and shall be suitable for indoor installation under the specified conditions.

With regard to any references made to padlocking in this specification, padlocks, to be provided by Supplier, have 6mm diameter hasp with 25mm clearance.

Other requirements express herein may not apply to gas insulated switchgear.

4.2. Rating.

The equipment shall be rated as detailed herein and in the attached Technical Schedule.

Each component of the equipment supplied shall be capable of continuous operation at the specified ratings without exceeding the temperature rise requirements of IEC 298, taking into account the specified ambient conditions.

4.3. Circuit Breakers.

4.3.1. Circuit breakers shall be of vacuum or SF6 type, and shall conform with IEC 298 and IEC 56, unless otherwise specified.

4.3.2.Each circuit breaker shall be a three pole, single throw unit, complete with operating mechanism and other required devices, mounted on a draw-out carriage.

Removable breaker units of the same type and rating shall be wired alike and shall be mechanically and electrically interchangeable. Circuit breakers of different ratings shall not be interchangeable.

4.3.3. If the circuit breakers employ an extinguishing medium of SF6, the first filling shall be supplied.

4.3.4. Breakers shall be fully withdrawable from the front of the switchgear, and metallic shutters shall be provided which automatically cover the bus and circuit orifices when the breaker is withdrawn. Provision shall be made for padlocking each shutter independently in the closed position (but not the open position). The opening operation shall also be automatic, and drive shall be positive in both opening and closing directions. Independent manual operation of shutters shall also be possible.

For test and maintenance purposes, an integral device shall be provided for retaining each shutter independently in the open position and subsequently releasing it to the closed position.

Insertion of the breaker trucks shall cancel the effect of the device, restoring automatic operation. Alternatively it is not possible to insert the breaker trucks till the above device is reset through some other means.

Shutter marking shall be in accordance with Item (5).

4.3.5.The operating mechanism shall be of the motor-charged spring, stored energy type, suitable for local or remote operation. Manual spring charging shall also be possible. Mechanical indication of spring state of charge shall be provided, with indicators marked as detailed in Item (5). Indicators shall be positively driven in both directions.

The operating mechanism shall be electrically and mechanically trip free.

A closing coil and shunt trip coil shall be provided, and all operating devices shall be designed to operate at the nominal control voltage specified.

If the energy storage system is not fully charged, breaker operation shall be blocked. Provision shall also be made so that tripping of the opening spring during a closing operation does not occur. In addition, the operating mechanism shall be anti-pump.

The breaker main contacts shall not touch or arc across into a faulted circuit when a breaker close signal is received while a trip signal is being applied.

Each breaker shall have a manual trip push button which mechanically trips the breaker.

The manual trip push button and its associated breaker trip linkage shall have no common components with the electrical trip mechanism, except the final breaker release device. The manual trip button shall be shrouded to avoid inadvertent operation.

Each breaker shall be furnished with non-resettable operations counter which shall be readable from the front of the switchgear with the breaker in the connected position.

Under all conditions, mechanism drive shall be positive in both directions, and the mechanism and moving contacts shall operate simultaneously.

4.3.6. Mechanical indication of the operating positions of the circuit breaker shall be provided. The indicators shall be positively driven in both directions via the circuit breaker operating mechanism to show whether the breaker is "ON" or "OFF" in the service, test and disconnected positions. The indicators shall be marked as detailed in Item (5).

4.3.7.Locking facilities shall be provided so that, with the breaker in any position, the breaker can be prevented from being closed when it is open.

Each requirement shall be met by the fitting of a separate single padlock, and shall not require the use of any additional loose components. It shall not be possible to readily gain access to the manual trip push button or any part of the mechanism which would permit defeat of the locking of the manual tripping. Similarly it shall not be possible to defeat the locking of the breaker when it is in the open position.

It shall not be possible to mechanically lock the trip mechanism so as to render the electrical tripping inoperative.

4.3.8. A manually operated control switch shall be provided on each breaker to provide control of breaker operations as outlined in Table 3:

BREAKER CONTROLBreaker DrawoutBreaker Operation

Remote ControlLocal Control

Position Close TripCloseTrip

Service x x x x

Test - - - -

Disconnected - - - -

Each circuit breaker control switch shall have a TRIP-NORMAL-CLOSE, PUSH-LOCAL, PULL-REMOTE escutcheon; shall have a spring return to centre position (normal position) from close and trip positions; shall have red and green targets to indicate the latest operation of the switch (red-ON, green-OFF; shall have no rotary movement when in the remote (OUT) position.

Discrepancy switches or push buttons in conjunction with dedicated remote-local switches are also acceptable.

4.3.9.Each breaker shall be furnished with a sufficient number of auxiliary contacts and auxiliary switch contacts to provide all necessary interlocks for the operation and control of the breaker. Minimum contact rating shall be 10 amperes at 125V dc.

Each breaker shall have not less than two "a" type and two "b" type electrically separate auxiliary contacts mounted on the breaker for remote interlocking service. A wipe contact to indicate breaker trip shall also be provided. Additionally, four spare "a" type and four spare "b" type contacts shall be provided on each breaker for use on SER and SCADA.

Each switchgear unit containing a circuit breaker shall be furnished with not less than eight "a" type and eight "b" type electrically separate breaker mechanism operated auxiliary switch contacts mounted in the switchgear unit enclosure for remote interlocking service.

Auxiliary switches shall be positively driven in both directions. They shall be mounted so as to be readily accessible for maintenance and designed to facilitate inspection, cleaning and adjustment. Contact surfaces shall be of a metal which is not subject to oxidization leading to an increase in contact resistance. Provision for trip circuit supervision shall be made.

All additional auxiliary contacts shall be wired to terminal boxes for external connection. Terminal boxes shall be mounted to obviate the need for routing control/instrumentation cables up through the cubicle to the LV panel.

Breaker interlocking shall be in accordance with sub-clause (4)4.4.5.

Door interlocks which trip the breaker when the door is opened shall not be furnished.

4.4. Grounding Switch/Grounding Trucks.

4.4.1.Facilities shall be provided on the equipment for short-circuiting to ground each incoming or outgoing circuit, and additionally each busbar section.

This may be achieved preferably by integral grounding switches, or, where temporary grounding is required, by the use of grounding trucks.

The use of loose accessories is not permitted.

4.4.2.Where grounding switches are supplied, these shall be manually operated, high speed type, having full fault making capacity, and rated in accordance with the Technical Schedules . Grounding switches shall conform to IEC 298 and IEC 129.

Grounding switches shall be operated from the front of the cubicle, and shall be equipped with anti-reflex operating handles. Grounding switch operating handles shall be clearly labelled as such, including positive mechanical indication of ON and OFF positions, and the direction of movement to each position.

It shall only be possible to ground incoming or outgoing circuits with the associated circuit breaker in the disconnected position.

Padlocking facilities shall be fitted to enable the grounding switch to be locked in either position. Interlocking shall be in accordance with sub-clause (4)4.4.5.

Operation of grounding switches shall not endanger adjacent components nor cause contamination or damage such that immediate removal from service for overhaul is necessary.

4.4.3.Where temporary grounding is required, grounding may be achieved using a grounding truck having an integral grounding switch as detailed above.

Key locking or padlocking facilities shall be provided for both the truck and the switch in all positions.

Interlocking shall be in accordance with sub-clause (4)4.4.5.

4.4.4. Each grounding switch shall be provided with not less than two "a" type and two type "b" electrically separate auxiliary contacts. Contact specification shall be as described in Sub-clause (4)4.4.3.9.

4.4.5. All metal parts of the cubicle shall be connected to a grounding conductor extending the whole length of the metal-clad switchgear, in accordance with IEC 298. (See also sub-clause (4)4.4.7.).

4.5. Interlocking.

4.5.1. Circuit Breaker/Truck.

Robust fail-safe mechanical and electrical interlocks shall be provided to prevent the following circuit breaker/breaker truck operations, where applicable:

SYMBOL 183 \f "Symbol" \s 11 \hThe breaker truck being moved into or from the service position with the circuit breaker closed. Attempted isolation shall not trip a closed circuit breaker.

SYMBOL 183 \f "Symbol" \s 11 \hThe operation of the circuit breaker while the truck is not properly installed in the service, test or disconnected position.

SYMBOL 183 \f "Symbol" \s 11 \hThe breaker truck being moved into the service position unless it is correctly located.

SYMBOL 183 \f "Symbol" \s 11 \hThe auxiliary connections being uncoupled with the breaker in the service position.

SYMBOL 183 \f "Symbol" \s 11 \hThe circuit breaker being closed in the service position unless the auxiliary connections are made.

SYMBOL 183 \f "Symbol" \s 11 \hThe breaker truck being withdrawn past the disconnected position before the auxiliary connections have been uncoupled.

SYMBOL 183 \f "Symbol" \s 11 \hThe breaker truck being moved into the service position without the auxiliary connections being made.

4.5.2. Grounding Switches.

Where cubicles are equipped with grounding switches, the following grounding switch operations shall not be possible:

SYMBOL 183 \f "Symbol" \s 11 \hClosing the grounding switch unless the breaker truck is in the disconnected position.

SYMBOL 183 \f "Symbol" \s 11 \hMoving the breaker truck into the service position while the grounding switch is closed.

4.5.3. Grounding Trucks.

Where grounding trucks are utilised, the following grounding truck/grounding switch operations shall not be possible:

SYMBOL 183 \f "Symbol" \s 11 \hInsertion of the grounding truck while the grounding switch is in the closed position.

SYMBOL 183 \f "Symbol" \s 11 \hRemoval of the grounding truck while the grounding switch is in the closed position.

4.6. Main Bus

The switchgear main bus shall be electrolytic grade copper bar fabricated in modular sections.

The busbar shall be able to withstand the mechanical stresses induced under the specified short circuit conditions.

Provisions shall be made for bus expansion to prevent undesirable or destructive mechanical strains in the bus supports and connections through the full ambient temperature range as specified. Expansion joints shall be furnished if necessary.

Moulded insulation or heat shrinkable shroud shall completely encase the bus and any connections.

Provisions shall be made for extending the busbar at either end without any need for cutting or drilling the copper bar.

Bus ConnectionsConductors shall be provided for interconnecting the main bus and instrument transformers, circuit breakers etc. All load current carrying conductors shall be flat bar or acceptable equal, conductors and connections being completely encased in moulded insulation or heat-shrinkable shroud. All connections shall be bolted.

Instrument transformer primary connections shall be designed to permit removal and replacement of the transformers without damage to the connections.

Connections between circuit breakers and busbars shall have the current rating of the highest rated circuit breaker.

4.7. Ground Bus.

An uninsulated, electrolytic copper ground bus shall be furnished throughout the entire length of the switchgear. The ground bus shall be sized to withstand the specified fault levels.

Connectors shall be furnished for the attachment of up to 185sq.mm stranded copper cable to each ground bus for external connection to the station grounding system.

Provision shall be made for extending the ground bus at either end without any need for cutting or drilling the copper bar.

4.8. Control and Instrument Wiring.

All low voltage control and instrument wiring shall be installed and tested at the factory.

All Interior wiring shall be numbered with plastic tags and neatly and carefully installed in wiring gutters or conduit and shall be terminated at terminal blocks in accordance with sub-clause (4)4.4.9.

Extra flexible wire shall be furnished at hinge points. These wires shall be tied suitably to avoid looseness.

Wires and terminals shall be plainly lettered or marked in accordance with the connection diagrams. Wires shall be colour coded in accordance with differing voltage levels.

Switchgear units which are split for shipment shall be furnished with all wiring required to interconnect the switchgear units.

600V PVC insulated, stranded copper conductors shall be used for all control and instrumentation wiring. Terminations shall be compression type, all wires being numbered in accordance with Tender drawings.

4.9. External Connections.

4.9.1. Terminal Blocks.

Low voltage terminal blocks shall be grouped in the same vertical section which contains the devices to which they are connected. Terminal blocks shall be mounted vertically or horizontally. (See also sub-clauses (4)4.3.9 and (4)4.4.8).

4.9.2. Breaker Isolating Contacts for Secondary Circuits.

Connections in the secondary circuits between each breaker truck and the fixed portion of the equipment shall be by means of self-aligning contacts or plug and socket type connectors. Means shall be provided for connecting the secondary circuits on the fixed portion to those on the breaker truck when the breaker truck is in the disconnected position.

Secondary isolating contacts shall be so positioned or designed to prevent the danger of electric shock when disconnected.

Cable terminations shall be dry type, and transformer and feeder cubicles shall have provision for termination of solid dielectric cables as detailed in the attached Technical Schedule. Heat-shrink type terminations will be used.

All necessary fixing nuts, bolts, washers etc., shall be supplied suitable to fix lug and glands supplied by SEC-SOA .

Provision shall be made by means of removable links or otherwise for the application of test voltages to cables. Disconnection of cables for test purposes is not acceptable.

4.9.4. Testing Plugs.

Portable testing plugs for insertion into circuit breaker isolating contacts shall be provided. These shall provide for the attachment of test connections.

Testing plugs shall conform to the requirements of IEC 298. Rated continuous current shall be 200A. Plugs shall be marked with the appropriate voltage rating.

Provision shall be made for securing plugs in position whilst in use.

A suitable box or container shall be supplied for storage of test plugs.

4.10. Control Power.

Electrical power for control and instrumentation shall be 220/127 V ac, auxiliary power 125V dc for control and protection and 48V dc for telecontrol.

All internal wiring required to distribute control power to each cubicle shall be furnished. The supply to each individual cubicle shall be protected by MCBs.

Each breaker shall be furnished with an MCB in the closing circuit and a similar device in the tripping circuit.

MCBs shall be supplied as necessary for mimic panel indication circuits.

MCBs shall have auxiliary contacts for alarm indication.

4.11. Current Transformers.

4.11.1. General.

CTs shall be in accordance with IEC 185, accuracy class of 10 P20, unless otherwise specified, and shall be of epoxy resin encapsulated design. Transformers/cores intended for use in differential protection schemes shall meet the requirements of BS 3938 for Class X units.

All CT secondary leads shall be wired out to terminal blocks, and provision shall be made for:

SYMBOL 183 \f "Symbol" \s 11 \hShorting out of CT windings to facilitate disconnection and testing of associated circuits (Switchgear shall be delivered with all CT secondary windings shorted out).

SYMBOL 183 \f "Symbol" \s 11 \hDisconnection of external circuits and connection of test instruments for testing CTs.

If test plugs are mounted on front panels they shall be suitably shrouded.

Terminal markings and rating plates shall be in accordance with IEC 185. Rating plates shall be mounted in a clearly visible position, external to the current transformer compartment if necessary.

No CT shall be mounted on a breaker truck.

4.11.2. Ratings.

Each current transformer shall have an output which is adequate for the correct working of relay protection devices and instruments over the required range of load and fault duties. The rated output and magnetisation curves of metering cores shall be such as to prevent damage to the instruments connected when the rated short-time current flows in the current transformer primary.

The knee point emf, secondary winding resistance and exciting current of protection cores shall be such as to ensure correct operation of the protective relays.

Rated primary currents and current ratios shall be in accordance with the requirements of the accompanying single line diagram. IEC 185 preferred values shall be used.

4.11.3. Grounding.

Where current transformer windings require to be grounded, they shall be connected to the ground bus by a direct copper connection, via a removable link. Each current transformer secondary circuit shall be grounded at only one point.

4.12. Voltage Transformers.

4.12.1. General.

VT's shall be in accordance with IEC 186 unless otherwise specified, and shall be of epoxy resin encapsulated design.

All secondary leads shall be wired out to terminal blocks.

Each transformer shall be provided with withdrawable current limiting primary fuses and miniature circuit breakers (MCB) in the secondary circuit. MCB's shall have auxiliary contacts for alarm indication.

Transformers and primary fuses shall be mounted on a drawout type removable unit designed to isolate and ground the potential circuits when the unit is in the fully withdrawn position.

Provision shall be made for padlocking the transformer in the service position.

Safety measures shall be provided which automatically cover and isolates the bus or circuit orifices when the transformer is withdrawn. The opening operation shall also be automatic, and drive shall be positive in both directions. Provision shall be made for padlocking each shutter independently in the closed position (but not the open position).

For test and maintenance purposes, an integral device shall be provided for retaining each shutter independently in the open position and subsequently releasing it to the closed position.

Subsequent insertion of the transformer shall cancel the effect of the device, restoring automatic operation.

Marking shall be in accordance with Item (5).

Note: Equivalent safety measures, approved by SEC-SOA are acceptable as an option to metallic shutters.

4.12.2. Ratings.

Each voltage transformer shall have an output which is adequate for the correct working of relay protection devices and instruments over the required range of load and fault duties.

4.12.3. Grounding.

Where voltage transformer secondary windings are required to be grounded, they shall be connected to the ground bus via suitable terminal block links.

The terminal of the high voltage winding intended to be grounded shall be insulated from the case or frame and shall withstand the application of 2kV rms for 1 minute.

Provision shall be made so that, on plugging in a voltage transformer, the transformer chamber ground connection is made before the primary connections.

4.13. Switchgear Enclosures.

4.13.1. General

Enclosures shall meet the requirements of IEC 298 unless otherwise specified.

Switchgear equipment shall be mounted in vertical, modular, ventilated sections fabricated in steel and assembled to provide rigid free-standing structures. The degree of protection given by the enclosures shall be class IP51 in accordance with the requirements of IEC 529.

Control panels and associated wiring shall be in accordance with the relevant standards.

4.13.2. Construction.

Full metal-clad construction is required. To this end, grounded removable steel barriers shall be provided to create separate compartments for:

SYMBOL 183 \f "Symbol" \s 11 \heach circuit breaker.

SYMBOL 183 \f "Symbol" \s 11 \heach busbar section.

SYMBOL 183 \f "Symbol" \s 11 \heach set of cable sealing ends and current transformers.

SYMBOL 183 \f "Symbol" \s 11 \heach LV panel.

Where voltage transformers are utilised, a separate compartment shall be provided.

Self tapping screws shall not be used on the barriers. In addition, shutters shall be provided as described elsewhere in the specification.

Enclosures shall be easily extensible at either end without the need for cutting, drilling or welding. Welding is also prohibited for field assembly of units.

Provision shall be made for expansion and contraction of the enclosures due to thermal cycling, taking into account the specified ambient conditions and temperature rise due to load variations.

Enclosures shall be adequately braced to withstand the full severity of the specified short circuit conditions.

Where specified, extension busbar trunking shall be provided on each side of a busbar sectionaliser cubicle to permit the location of the equipment between fire barrier walls.

4.13.3. Finish.

Enclosures shall have a sufficient degree of corrosion protection for the specified environmental conditions. The colour of finish shall be Cement Grey to RAL 7033, the top coat being oil resistant.

4.13.4. Labelling.

Labelling shall be provided as described in Item (5).

4.14. Miscellaneous.

4.14.1. Lifting Facilities.

Each unit of equipment shall be provided with lifting facilities, and shall have its weight marked.

4.14.2. Switchgear Space Heaters.

Each unit shall be furnished with space heaters to prevent condensation forming. The heaters shall be located and thermally insulated such that no painted surface will be damaged or discoloured.

Space heater capacity shall be as required to maintain the compartment and unit internal temperature above the dew point, taking into consideration the specified environmental conditions.

An external AC, single phase, 220V, 60Hz supply will be provided to each switchgear assembly for space-heaters. All internal space heater wiring shall be provided in the switchgear.

Space-heaters shall be controlled by an adjustable humidistat or thermostat.

4.14.3. Arrangement.

The switchgear arrangement shown on the accompanying one-line diagram is preliminary only. In the event that a new arrangement is required, drawings will be furnished to and co-ordinated with the Supplier.

4.14.4. Accessories.

All necessary equipment required for assembly of separate cubicles into a single switchboard shall be provided. This shall include small wiring, fuses, labels, cable termination facilities, sole-plates, busbar interconnections and all other necessary sundries.

Also included, where applicable, shall be:

SYMBOL 183 \f "Symbol" \s 11 \h2 CB raise/lower handles.

SYMBOL 183 \f "Symbol" \s 11 \h1 set of high voltage test plugs.

SYMBOL 183 \f "Symbol" \s 11 \h2 sets of jumper connections

SYMBOL 183 \f "Symbol" \s 11 \h1 CB manual charging handle

SYMBOL 183 \f "Symbol" \s 11 \hSpecial tools.

SYMBOL 183 \f "Symbol" \s 11 \h2 sets of portable test equipment (Protective relay test set & VOM)

(5) MARKING

1. Nameplates

Nameplates (Rating plates) shall be provided in accordance with the detailed provisions of the referenced standards and specifications, unless otherwise specified.

2. Identification Labels

Identification labels and nameplates shall be made of laminated white phenolic engraving stock with black core. The lettering shall be hold, engraved through the outside layer so that the letters are the colour of the core.

Labels shall be attached to the equipment with stainless steel panhead screws.

Labels shall be used to identify switches, instruments, relays, circuits etc. Circuit labels shall be supplied blank, and engraved on site.

Circuit labels shall be fixed to the front and rear of the switchgear cubicles (but NOT on withdrawable portions).

Minimum letter height shall be 12mm for cubicle/circuit labels and 7mm for all other labels.

3. Shutters And Semaphore Flags

Markings on shutters and semaphore flags shall be as shown in the table (below).

4. Busbars

Busbars shall be marked to identify individual phases.

EQUIPMENT MARKING

EQUIPMENT ITEMLETTERINGCOLOR

LETTERINGBACKGROUND

Busbar orifice Shutters*BUSBARWhiteRed

Circuit orifice ShuttersCABLEWhiteYellow

Breaker "ON" flagONWhiteRed

Breaker "OFF" flagOFFWhiteGreen

Breaker "spring discharged" flagSpring DischargedBlackWhite

Breaker "spring charged " flagSpring ChargedBlackWhite

*Busbar orifice shutters in bus coupler cubicles shall also show a white arrow pointer in the direction of the relevant section of busbar.

5. Colour Coding

Colour coding of indicator lights and push buttons shall be in accordance with IEC 73.

(6) TESTING

The overall test of the sitchgear including its associated components shall be tested in accordance with the latest relevant IEC standards. All other requirements for factory tests, site test, tests certificates, witnessing of tests, etc., shall conform to those defined in other parts of this Tender documents.SECTION 4.2.1.11

TECHNICAL SPECIFICATIONSMedium Voltage Switchgears (33 & 13.8 kV) Page 16Reference NumberPTS# 05SR105