JERES-P-100 Basic Power System Design Criteria

JERES-P-100

Basic Power System Design Criteria

Revision 3

Responsibility JER Engineering Division

02 February 2009

Jubail Export Refinery Engineering Standard

Jubail Export Refinery Engineering Standards

JERES-P-100 Rev. 3

Basic Power System Design Criteria 02 February 2009

This document is the property of Jubail Export Refinery and no parts of this document shall be reproduced by any means without prior approval by the Company.

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Revision Tracking

Revision Revision Date Scope of Revision

3 02 February 2009 Reveised to update paragraph 9.4.5

2 04 November 2008 Revised to update paragraph: 3.4; 5.3.1; 5.3.2; 7.3.3.2; 9.1.3.13; 9.2.9; 9.4.5; 9.4.6.1; 9.11.4; 9.14.2.4; 10.1.6

1 11 July Revised to Update power supply of the refinery from 230 kV to 380 kV

0 29 April 2008 Issued for bid package.

04 16 April 2008 Integration of technical audit

03 31 March 2008 Issued for bid package – For review only

02 23 February 2008 Update

01 29 October 2007 The official JERES-P-100 is issued

00 20 February 2007 First draft issue.


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Table of Contents

Section Contents Page

1 Scope 4

2 Conflicts, Deviations and Clarifications 4

3 References 5

4 Definitions 7

5 Environmental Conditions 10

6 Vocabulary, Units and Symbols 10

7 Basis of Design 10

8 Electrical distribution system 16

9 Electrical Equipment Definition 20

10 Electrical Substations 47

Appendixes

Appendix A 54


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1. Scope

1.1 The aim of this technical specification is to describe the new electrical system and electrical equipment of the onshore plant located in Jubail area – Saudi Arabia, as well as to define the design criteria.

1.2 The purpose of the electrical power system is to distribute power to support all process, utilities, the control, the communication and security system. In addition, it must maintain emergency supply to equipment should the main power fail, and provide also uninterruptible power supply to vita equipment.

1.3 This design basis is to be read in conjunction with other project related design bases and/or specifications.

2 Conflicts, Deviations and Clarifications

2.1 Any conflicts between this standard and other applicable Company Engineering Standards (JERES), Material Specifications (JERMS), Standard Drawings (JERSD), Engineering Procedures (JEREP), Company Forms or Industry standards, specifications, Codes and forms shall be brought to the attention of Company Representative by the Contractor for resolution.

Until the resolution is officially made by the Company Representative, the most stringent requirement shall govern.

2.2 Where a licensor specification is more stringent than those of this standard, the Licensor’s specific requirement shall apply.

2.3 Where applicable Codes or Standards are not called by this standard or its requirements are not clear, it shall be brought to attention of Company Representative by Contractor for resolution.

2.4 Direct all requests for deviations or clarifications in writing to the Company or its Representative who shall follow internal Company procedure and provide final resolution.


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3 References

The selection of material and equipment, and the design, construction, maintenance, and repair of equipment and facilities covered by this standard shall comply with the latest edition of the references listed below as of the CUT-OFF DATE as specified in the Contract unless otherwise noted.

3.1 The reference documents listed below form an integral part of this general specification. Unless otherwise stipulated, the applicable version of these documents, including relevant appendices and supplements, is the latest revision published at the EFFECTIVE DATE of the CONTRACT.

3.2 Electrical power system shall be designed constructed and installed in accordance with the latest edition of IEC (International Electrotechnical Commission).

3.3 The following order of precedence applies to electrical design, electrical equipment and electrical installation:

JERES-P-100

JERES and JERMS Particular Specifications and data sheet (if any)

3.4 The selection of material and equipment, and the design, construction, maintenance, and repair of equipment and facilities covered by this standard shall comply with the latest edition of the references listed below, unless otherwise noted.

Company References

Company Engineering Standards

JERES-A-112 Meteorological and Seismic Design Data

JERES-B-008 Restrictions to Use of Cellars, Pits, and Trenches

JERES-B-017 Fire Water System Design

JERES-B-055 Plant Layout

JERES-B-068 Determination of Explosion Hazard Zones 0, 1 and 2

JERES-J-902 Electrical Systems for Instrumentation

JERES-K-001 Heating, Ventilating and Air Conditioning (HVAC)


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JERES-P-103 Batteries and U.P.S. Systems

JERES-P-104 Wiring Methods and Materials

JERES-P-107 Overhead Distribution Systems

JERES-P-111 Grounding

JERES-P-113 Motors and Generators

JERES-P-114 Power System and Equipment Protection

JERES-P-116 Switchgear and Control Equipment

JERES-P-119 Onshore Substations

JERES-P-121 Transformers and Reactors

JERES-P-123 Lighting

JERES-P-127 Electrical Control System

Company Materials Specifications

JERMS-P-4531 Power Transformers

JERMS-P-4533 Three-Phase Dry-Type Power Transformers

JERMS-P-5503 Electrical Cables

JERMS-P-6502 Metal Enclosed Low-Voltage Switchgear Assemblies

JERMS-P-6503 Indoor Controlgear – Low-Voltage

JERMS-P-6504 Indoor Metal-Clad Switchgear 1 to 38 kV

JERMS-P-6506 Indoor Controlgear – High Voltage

JERMS-P-6508 SF6 Gas Insulated Circuit Breakers, Indoor – 69 kV through 380 kV

JERMS-P-6513 Protective devices

JERMS-P-6514 Control and protective Relay Panel – Indoor

JERMS-P-6515 Design and fabrication of high resistance grounding system

JERMS-P-6516 Low Voltage Adjustable Frequency Drive System

JERMS-P-6518 Low Voltage Panel Boards


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JERMS-P-6519 Indoor Switchboard - Low Voltage

JERMS-P-6521 Indoor Automatic Transfer Switch – Low Voltage

JERMS-P-7502 Form-Induction Motors

JERMS-P-7503 Severe Duty Totally Enclosed Squirrel Cage Induction Motors to 250 HP

JERMS-P-7510 Form – Wound Synchronous Turbine Generators

JERMS-P-7511 Stationary Storage Batteries

JERMS-P-7514 Battery Chargers/Rectifier

JERMS-P-7515 Auxiliary Electrical Systems for Skid-Mounted Equipment

JERMS-P-7516 Uninterruptible Power Supply System

JERMS-P-7518 Emergency Diesel Generator

JERMS-P-7520 Form Wound Brushless Synchronous Motors

4 Definitions

4.1 Definitions presented in this Standard and other JER documents have precedence over other definitions. Conflicts between various definitions shall be brought to the attention of Company Representative by the Contractor for resolution.

Company: Jubail Export Refinery.

Company Representative: A designated person from the Company or an assigned third party representative.

Company Inspector: A designated person or an agency responsible for conducting inspection activities on behalf of the Company.

4.2 List of Definitions

Base Voltage: The bus voltage calculated by starting with the nominal voltage at the swing bus and calculated for each bus based on the transformer turns ratios.

Bus Tie Breaker: A breaker used to connect the two busses of secondary-selective system.


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Captive Transformer: A transformer whose output is dedicated to a single piece of utilization equipment.

Controlgear: Equipment manufactured to either JERMS-P-6503 (Low Voltage Controlgear) or JERMS-P-6506 (High Voltage Controlgear).

Normal service Loads: Are loads where a single contingency failure could cause a loss of power which do not create an immediate hazard to human life or cause a significant reduction in JER total production. Normal (Non critical) service loads tolerate prolonged power failure without causing plant shut down. Examples of normal loads are: Secondary office buildings, Warehouses and Workshops.

Critical Loads: Are loads where a single contingency failure could cause a loss of power which would create an immediate hazard to human life or cause a significant reduction in JER total production, or which cannot be shut-down for a minimum of five consecutive days annually for scheduled maintenance on upstream power supply equipment. Examples of critical loads are: major computer centers, critical care areas in clinics and hospitals, major office buildings and process units in refineries. Only secondary-selective switchgear shall be used to feed critical loads. Critical facilities or equipment could be directly supplied from steam turbine generators in case of black out condition.

Emergency loads: Are loads whose operation involves the safeguard of an item of equipment/installation or the continuation of certain operations. In case of shutdown, emergency loads tolerate a short interruption of service, but it shall be automatically restarted and re-fed by emergency generator. Examples of emergency loads are: Plant emergency lighting system and AC and DC UPS. Only secondary-selective switchgear plus emergency generator shall be used to feed emergency loads.

Vital loads: Are loads whose operation affects personnel safety whether directly or indirectly. Vital load does not allow the power supply interruption and shall be fed by UPS systems. Examples of vital loads are: Process vital service instrumentation and Substation control systems. Only AC or DC UPS shall be used to supply vital loads.

Demand: Electrical load averaged over a specified time period.

High Voltage: Voltages 1000 V or greater unless otherwise designated or referenced international standard.


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Low Voltage: Voltages less than 1000 V, unless otherwise designated or referenced international standard.

Nominal Voltage: Refer to Table 1.

Operating Load: Depending on the nature of the loads, the operating load may be substantially less than the total connected load.

For new facilities: Anticipated one-hour demand based on plant or facility design conditions.

For existing facilities: When data from metering equipment is available: Maximum 60-minute demand measured over a minimum of one year.

PCB free: Containing less than 1 ppm Polychlorinated biphenyl.

Secondary-Selective: A switchgear assembly consisting of two buses connected with a single bus tie breaker. Each bus has one breaker to receive incoming power. (i.e., power flow into and between the two busses is controlled with three breakers). These schemes are standardized. Refer to JERES-P-116 for standardized schemes.

Severe Corrosive Environment: As described in Section 9 of this standard.

Switchgear: Equipment manufactured to either JERMS-P-6502 (Low Voltage Switchgear) or JERMS-P-6504 (High Voltage Switchgear).

UPS: Uninterruptible Power Supply.

Utilization device/equipment: Equipment whose primary function is to convert electrical energy to another form or store electrical energy. Examples of utilization equipment would be motors, heaters, lamps, batteries, etc. Equipment directly feeding/controlling the utilization equipment is considered part of the utilization equipment (e.g., AFDs, reduced voltage starters, battery chargers, etc.).

General load shedding: load shedding system implemented to shed normal electrical loads in case of black out condition.

Local load shedding: load shedding system implemented inside electrical switchgear and controlgear before automatic transfer of source.


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5 Environmental Conditions

5.1 Electrical equipment design and installation shall be performed in accordance with the data given in the “Meteorological and Seismic Design Data”

5.2 Outdoor electrical equipment shall be designed to operate continuously in an ambient temperature corresponding to the extreme outside temperatures as defined in the project specific environmental data.

5.3 Electrical equipment shall be rated in accordance with the requirements of the electrical JERES or JERMS specific to the equipment and its installation. When not covered in these documents:

5.3.1 For ambient temperature: The temperature criteria defined in JERES-A-112 shall be used to establish equipment rating.

5.3.2 According to the design temperature of the air conditioning system (refer to JERES-K-001 and 002), ambient air temperature inside electrical substation shall be 25 °C +/- 1 °C. Refer to JERES-P-103 for battery rating.

6 Vocabulary, Units and Symbols

6.1 The Electro technical vocabulary and graphical symbols used shall be as defined in the IEC 60050 and IEC 60617.

6.2 Units used shall be as defined in the International System of units (SI).

6.3 In case of utilization of any vocabulary, units or symbols that are not in the above IEC publications, the Engineering is required to produce a glossary (for vocabulary), correspondence table to IEC units (for units) and/or clear legend (for symbols).

7 Basis of Design

7.1 General

7.1.1 The complete electrical system shall be designed to enhance personnel safety and to minimize environmental exposure of the electrical equipment. In addition, the electrical systems shall be designed for lowest life cycle cost, continuous and reliable service, equipment protection, ease of maintenance and operation, mechanical


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protection of equipment, interchangeability of equipment, and the addition of future loads.

7.2 Frequency

7.2.1 The frequency of alternating current electrical power system shall be 60 Hz.

7.2.2 At all times, AC equipment shall operate satisfactorily at frequencies within ± 2%.

7.3 Voltages

7.3.1 The Company will be supplied from the national grid by two 380 kV Feeders. The primary distribution system within the Refinery shall be 34.5 kV. The secondary distribution system will be 13.8 kV, 4.16 kV and 480 V.

7.3.2 Selection of voltage shall be based on the following parameters:

a) Power to be delivered ( based on the power balance established for each consumer voltage level)

b) Short circuit levels,

c) Distributor’s supply voltage,

d) Distance between consumers and supplies.

7.3.3 AC Systems

7.3.3.1 Electrical equipment shall operate satisfactorily during voltage fluctuations within ±10 % of the stated voltage levels when connected to a local grid and ± 5 % when operating in island mode.

7.3.3.2 High voltage: The general electrical characteristics shall be in accordance with the values indicated as follow:

System Voltage

Nominal voltage (RMS values) 4.16 kV 13.8 kV 34.5 kV 380 kV


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Highest voltage for equipment Rated voltage Ur (RMS value)

7,2 kV 17,5 kV 40,5 kV 420 kV

Rated short duration power frequency withstand voltage Ud (RMS value)

19 kV 50 kV 95 kV 650 kV

common value

Rated lightning impulse withstand voltage Up (peak values)

60 kV 95 kV 185 kV 1425 kV common

value

Number of phases 3ph 3ph 3ph 3ph

Number of wires 3w 3w 3w 3w

Neutral system Low resistance Low resistance Low resistance

Requirements 50A, 10seconds resistor

400A or 1000A. 10seconds

resistor / 50A if motor supplied from 13.8 kV

captive transformer

1000A According

SEC requirement

7.3.3.2.1 Steady state voltage:

a) At branch circuit/distribution equipment connection points (for instance, switchgear, control gear, etc.): 95 % to 105 % of nominal voltage.

b) At the utilization devices: 90 % to 110 % of nominal voltage.

7.3.3.3 Low voltage: The general electrical characteristics shall be in accordance with the values indicated as follow:

System Voltage

Nominal voltage (RMS values) 120/240V 120V /

208V Y

277V /

480V Y 480V 480V

Highest voltage for equipment Rated voltage Ur (RMS value) Hold Hold Hold Hold Hold


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Rated short duration power frequency withstand voltage Ud (RMS value)

Hold Hold Hold Hold Hold

Rated lightning impulse withstand voltage Up (peak values) 1,5kV 1,5kV 2,5kV 4kV 4kV

Number of phases 1ph 3ph 3ph 3ph 3ph

Number of wires 3w 4w (3cores+earth)

4w (3cores+earth)

4w (3cores+earth)

4w (3cores+earth)

Neutral system Solidly earthed Solidly earthed Solidly

earthed Solidly earthed

High resistance

Requirements See note 1

Note 1: subject to Company approval.

7.3.3.3.1 Steady state voltage:

a) At branch circuit/distribution equipment connection points (for instance, switchgear, control gear, etc.): 95 % to 105 % of nominal voltage

b) At light fixtures: 90 % to 110 % of nominal voltage

c) At the utilization devices: 90 % to 110 % of nominal voltage.

7.3.4 DC Systems

a) 125 VDC for electrical control, essential lube oil pumps (e.g. turbo generators, turbo compressors, etc. In this case, dedicated DC UPS shall be designed and provided by Vendor), positive and negative isolated from the earth ground

b) Refer to Telecom specification for telephone system (PABX), public address (PA/GA).

7.3.5 System Voltage Drops

7.3.5.1 The maximum allowed voltage drops at equipment terminals are based on the system nominal voltage.


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7.3.5.2 AC Systems

7.3.5.2.1 The distribution system cable sizing shall ensure that the following voltage drops, at the circuit full load current, are not exceeded:

a) Feeder (from main to sub-main switchboard & MCC) : 2 % of nominal voltage

b) Transformer feeders (from transformer to switchboard) : 1 % of nominal voltage

c) Motor feeder terminals : 5 % of nominal voltage

d) Lighting sub-circuits and sockets: 2% average with a maximum of 8% at to the farthest fitting.

e) Other (heaters, packages…) : 5% unless particular requirement

7.3.5.2.2 During motor starting, voltage at motor terminals shall ensure a sufficient accelerating torque, and voltage drop at bus bar shall not cause shutdown of other consumers.

7.3.5.2.3 When a motor is starting, the voltage at every utilization device, anywhere in the electrical system, shall not drop below 85 % of the nominal voltage.

7.3.5.2.4 When a motor is starting, the voltage at the terminals of the motor being started shall not drop below 85 % of the rated motor voltage.

7.3.5.2.5 For high voltage motors, when approved and documented by the motor manufacturer, a drop up to 80% of rated motor voltage is permitted at the terminals of the motor being started. Dedicated study shall be provided by Contractor to Company.

7.3.5.2.6 For high voltage motors equipped with captive transformers, starting conditions will be defined by the manufacturer of the motor on the basis of short circuit power defined by Company at the motor terminal. In this condition, manufacturer is free to select motor voltage and starting current versus nominal current (Id/In).

7.3.5.3 DC Systems

7.3.5.3.1 The voltage drop through DC distribution shall not exceed 2% of nominal voltage taking into account inrush current and transient loads.


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7.3.6 Earthing System

7.3.6.1 High voltage systems:

a) 380 kV: As the installation is derived from a Local Electricity Grid, the neutral system and the relevant fault value are imposed by the Local Electricity Board.

b) 34.5 kV: As specified in table 1, the neutral of 34.5 kV system is earthed via a low resistor. The neutral point of the secondary side of each 380kV/34.5kV transformers will be connected to the earth through a resistor limiting the earth fault value to 1000 A.

c) 13.8 kV: As specified in table 1, the neutral of 13.8 kV system is earthed via a low resistor. The neutral point of the secondary side of each 34.5 kV/13.8 kV transformers will be connected to the earth through a resistor limiting the earth fault value to 400 A or 1000A or 50A if motor supplied from 13.8 kV captive transformer

d) 4.16kV level: As specified in table 1, the neutral of 4.16kV system is earthed via a low resistor The neutral point of the secondary side of each 34.5 kV/4.16 kV transformers will be connected to the earth through a resistor limiting the earth fault value to 50 A.

7.3.6.2 Low voltage systems:

a) The main low voltage system (480 V, 3-phase, 3 wires) shall be earthed by high impedance (diagram IT) with neutral not distributed.

b) In case of supply by HV/LV transformer, a surge arrester shall be installed between the neutral and the earth on the LV side.

c) Permanent earth fault monitoring device shall be installed on each L.V. switchboard busbar. Only one device shall be in operation when bus tie is closed.

d) An earth fault leakage relay (with time delay if required) shall be provided for each consumer, it shall be set only to trip when a second fault occurs.

8 Electrical distribution system


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8.1 The following principles shall be applied regarding the basic requirements and configuration of the generation and distribution systems.

8.2 General

8.2.1 The complete electrical system shall be designed to enhance personnel safety and to minimize environmental exposure of the electrical equipment.

8.2.2 In addition, the electrical systems shall be designed for lowest life cycle cost, continuous and reliable service, equipment protection, ease of maintenance and operation, mechanical protection of equipment, interchangeability of equipment, and the addition of future loads.

8.2.3 Moreover, the distribution systems shall be designed to fulfill the following requirements to:

a) allow remote operation from a centralized control room, or technical room,

b) Design the system for which the necessary elements e.g. switchgear, cables, etc. are currently manufactured, and tested. Industrial type equipment with a minimum of two years field proven experience is required.

8.2.4 Selection of equipment shall also be based on Operational Expenditure (OPEX) and Capital Expenditure (CAPEX) considerations. The primary difference between OPEX and CAPEX is that OPEX is used for the day to day running of an organization and CAPEX is used for the purchase of assets which have a relatively long life.

8.3 Equipment rating/sizing

8.3.1 Equipment sizing for each installation shall be such that all extensions known at design phase shall be taken into account.

8.3.2 As a general rule, and unless otherwise specified in a particular project specification, all equipment (main and/or essential generator, transformers, switchgears, UPS, DC systems, MCC bus bar, etc.) of the power distribution system shall have at least 20 % spare capacity above the expected load at the starting of the plant.

8.3.3 All components (e.g. bus bars, circuit breakers, contactors, switches, etc.) and cables shall be rated for at least the rating of the equipment to which they are connected.


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8.3.4 The equipment short circuit rating shall be at least 20 % above the expected fault level value at the starting of the plant (except for the 380 kV switchgear).

8.3.5 The short circuit rating of all HV and LV switchboards shall be defined with one transformer in operation (bus tie normally close) and all consumers for normal operation in service.

8.4 Design allowances

8.4.1 As a minimum, to determine electrical substation arrangement, For HV and LV switchgear and controlgear, available space of 20% of the total length of the switchboard with at least a minimum of one cubicle at each side shall be provided for future extension.

8.5 Electrical Network Studies

8.5.1 System studies are required for new facilities and major additions to existing facilities.

8.5.2 The following studies shall be performed to issue proper design of the electrical power systems and equipment:

a) Load-flow.

b) Short-circuit.

c) Motor-starting.(voltage drop calculation),

d) Stability studies,

e) Earthing system calculation,

f) Harmonic analysis

8.5.3 The Electrical Transient Analyzer Program (ETAP) Power Station (Windows version) shall be used to conduct the above studies.

8.5.4 Additionally, the studies indicated below shall be performed on a case-by-case basis.

a) Transient Stability: For facilities with generation greater than 10MW.


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b) Harmonic Analysis: If a non-linear load (e.g., AFD, Power Converters, etc.) is included in the power system. The IEEE-519 standard will be the basis for the harmonic studies. Refer to JERMS-P-6517 for details.

c) Switching Transient Analysis: If supply is affected by induced capacitive switching transients (e.g., shunt capacitor banks or lengthy HV cables).

8.5.5 Actual system data and constraints shall be used for all studies.

8.5.6 Unless the actual impedance of a transformer is known from the transformer tests, 7.5 % transformer impedance tolerance shall be used so that the specified design impedance is increased by 7.5 % for load flow and motor starting calculations and decreased by 7.5 % for short circuit calculations.

8.5.7 For motor-starting studies, maximum source impedance shall be used in calculating voltage drops. Motor starting studies shall be performed with all other motors running at normal load.

8.5.8 Maximum system voltage levels shall be determined assuming all motor loads are disconnected and in the case of secondary-selective substations that both transformers are operational and the bus tie breaker is in its normal state.

8.5.9 Normal system voltage levels shall be based upon operating load.

8.5.10 Minimum voltage of each circuit shall be based on the normal operating load plus the operating load of the largest spare (standby) motor if the spare motor is not interlocked to prevent starting while the primary motor is running. Minimum voltages down stream of secondary-selective substations supplying utilization devices shall be calculated assuming that one transformer is out of service and the bus tie breaker is closed.

8.5.11 For short circuit studies, the maximum ultimate 3-phase short circuit fault-current shall be used with a pre-fault voltage of 110% of the bus base voltage. Short circuit studies for secondary-selective substations with normally open bus tie breakers shall be evaluated assuming that one incomer breaker is open and the bus tie breaker is closed (i.e., one transformer is supplying the entire load).

8.5.12 For new transformer installations, transformer off-load tap settings shall be assumed to be at the mid-point (neutral position). For analysis of existing systems, actual


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transformer off-load tap settings shall be used. When calculating minimum voltage levels, it is acceptable to assume that the off-load transformer taps can be set one step off the neutral position. In this case, all studies shall use the same transformer tap position.

8.5.13 For switchgear fed by transformers with on-load tap changers, it is acceptable that the load flow studies assume that these tap changers will automatically regulate the voltage on the secondary switchgear bus, directly connected to these transformers, to the nominal voltage.

8.5.14 Sizing of the electrical system shall be based upon using 120 % of the total operating loads.

8.5.15 UPS distribution systems design shall also ensure that short-circuits, anywhere in the system, that drops the nominal voltage at any utilization device, or utilization device distribution equipment upstream of the short circuit location to less than 90 %, shall be cleared within (four) 4 milliseconds.

8.6 Hazardous areas and restricted areas

8.6.1 The hazardous area classification and restricted area drawings shall be prepared by the SAFETY discipline in accordance with project requirement.

8.6.2 Where electrical equipment has to be installed in hazardous area, equipment with a type of protection suitable for the relevant zone shall be selected and specified in accordance with as follow:

Equipment Zone 0 Zone 1 Zone 2

High Voltage motor

Flameproof enclosure “d” or “de”

Pressurized enclosure “p”




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Low Voltage motor




Increased safety “e”

Type of protection “n”

Lighting fixture Flameproof enclosure “d” Flameproof enclosure “d”

Junction box Intrinsic safety “ia” Flameproof enclosure “d”

Intrinsic safety “ia”

Flameproof enclosure “d”


Other Intrinsic safety “ia” Flameproof enclosure “d”



Type of protection “ed”

Equipment with contact Intrinsic safety “ia” Flameproof enclosure “d”


Type of protection “ed”

Local control station Intrinsic safety “ia” Flameproof enclosure “d” Flameproof enclosure “d”

Socket outlet Not Applicable Not Applicable Not Applicable

Power equipment Pressurized enclosure “p

Oil immersion “o”


Nota: EEx”p” type of protection shall be used for HV motors rated more than 1 MW only if EEx”d” motors are not proposed by approved suppliers listed in Company vendor list. This choice shall be submitted to Company approval

9 Electrical Equipment Definition

9.1 High Voltage


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9.1.1 HV switchgears and controlgears design shall meet the requirements of the specification JERES-P- 116 and shall fully comply with the latest edition of IEC standards.

9.1.2 380 kV switchgear

9.1.2.1 This switchgear shall be metal-enclosed “Gas Insulated Switchgear” (G.I.S.) type. The insulating media shall be SF6.

9.1.2.2 The main 380 kV HV switchgear shall be connected directly to the local electricity grid.

9.1.2.3 Main HV switchgear shall have as many buses sections as power sources (2 incomers) and shall be operated with “Normal Closed” tie breakers.

9.1.2.4 The incomer’s protections of the main switchgear shall be designed in accordance with the Local Electricity Board requirements.

9.1.2.5 Bus bar rating and distribution of the loads along the bus sections shall allow the load flow in any network configuration according to § 8.4.

9.1.2.6 Electrical Characteristics:

a) Rated voltage: 420 kV

b) Rated power frequency withstand voltage : 650 kV

c) Rated lightning impulse withstand voltage : 1450 kV

d) Rated switching impulse withstand voltage : 1050 kV

9.1.3 High voltage 34,5 kV - 13,8 kV and 4,16 kV switchgear

9.1.3.1 High voltage switchgears shall be metal-clad type, air insulated, and withdrawable type and shall be comprised of individual vertical sections sharing a common main circuit horizontal bus and a common ground bus.

9.1.3.2 The switching devices isolating and current interrupting media shall be either SF6 gas or vacuum with surge protection.


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9.1.3.3 High voltage switchgears sections (A and B) shall not be installed in a back to back configuration and not be in line configuration but shall be physically separated at minimum distance indicated in section 10.2.1.

9.1.3.4 The configuration to be retained is “separate bus bars”. The power link between the two bus sections shall be by cables. The use of bus bars is prohibited.

9.1.3.5 The complete assembly shall have a minimum of IP 31 “Degree of protection” as specified in IEC 60529 with all doors closed and IP 20 with doors open.

9.1.3.6 Switchgears shall be designed to permit the future in situ installation of vertical sections, at the end of each bus.

9.1.3.7 Each vertical section shall be completely enclosed on all sides and top with metal sheet.

9.1.3.8 The maximum number of material inside vertical section shall be either one (1) circuit breaker or two (2) Fuses/contactor outgoers.

9.1.3.9 HV switchgear with at least two power supplies shall have two bus sections. Status of tie breakers between bus sections of the downstream HV and LV switchgear shall be “Normally Open”.

9.1.3.10 In order to increase availability, redundant equipment shall be judiciously split between the different bus sections.

9.1.3.11 Each incomer of bus section cubicle (A and B) shall be equipped with microprocessor type protection and measurement relays. These relays shall be interfaced with the Electrical Control System. Motor feeder circuits shall not be interfaced with the ECS and if required shall be interfaced with the DCS.

9.1.3.12 Unless otherwise specified, circuit breaker control (closing and tripping) shall be achieved by means of a shunt trip coil (energize to trip).

9.1.3.13 Over pressure and internal arcing pressure relief vents shall be provided and shall be oriented to prevent any hazard to personnel or adjacent equipment.

Electrical characteristics:


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4,16 kV 13,8 kV 34,5 kV

Rated voltage 7,2 kV 17,5 kV 40,5 kV

Rated lightning impulse

withstand voltage

60 kV 95 kV 185 kV

Rated nominal current

(Bus bars and Incomers – Bus Tie)

1250 A – 2500 A – 3150 A

Rated short circuit

breaking current

50 kA 40 kA 31.5 kA

Rated duration of short circuit

current

3 seconds

Internal arcing

withstanding Same as Rated short circuit breaking current for 1 second

9.2 Low voltage switchboards

9.2.1 Low voltage switchboards design shall meet the requirements of the specification JERES P 116.

9.2.2 Low voltage switchboards shall fully comply with the latest edition of IEC standards.

9.2.3 Low voltage switchgears shall be Metal-Enclosed type and withdrawable type.


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9.2.4 Low voltage switchgears sections (A and B) shall not be installed in a back to back configuration and not be in line configuration but shall physically separated at minimum distance indicated in section 10.2.1.

9.2.5 Switchgears shall meet as a minimum “Form 4b” internal separation requirements as specified in the appendix D of IEC 60439-1

9.2.6 The complete assembly shall have a minimum of IP 31 “Degree of protection” as specified in IEC 60529 with all doors closed.

9.2.7 Switchgears shall be designed to permit the future in situ installation of vertical sections, at the end of each bus.

9.2.8 The switchgear shall be designed to permit the utilization of the location identified as spare or space:

a) without de energizing the switchgear main circuit and

b) by the use of simple fasteners and standard tools, and

c) While maintaining the enclosure integrity of compartmentalization.

9.2.9 VOID

9.2.10 The two bus sections (A and B), and associated incoming breakers (A and B) and bus tie breaker (C) can be in the following configurations:

a) Configuration 1: Incoming circuit breaker A and B closed and bus tie C open,

b) Configuration 2: Incoming circuit breaker A and the bus tie closed, incoming B open,

c) Configuration 3: Incoming circuit breaker B and the bus tie closed, incoming A open.

9.2.11 The configuration 1 represents the normal operating condition.

9.2.12 The configurations 2 and 3 may be used during maintenance on one of the incoming feeder.


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9.2.13 Transfer from one configuration to another one shall not cause any loss of supply to consumers, (make before break). This sequence will result in the three circuit breakers all being closed for a very short period of time (e.g. 1 sec). The short circuit rating of the switchboard however is not calculated to cover for this condition as the risk of a fault occurring at the instant when all three circuit breakers are closed is considered extremely unlikely. In all cases, the three circuit breakers shall never be simultaneously closed for more than 1 second as described above.

9.2.14 This transfer shall be controlled manually at the switchboard by selecting the “third” circuit breaker or at the Electrical Control System.

9.2.15 Additionally, the “third” circuit breaker selected shall be closed only if the requirements for safe coupling are met.

9.2.16 In normal operating configuration, loss of voltage on one half bus bars shall, after a time delay, automatically open the corresponding incoming circuit breaker and then close the bus tie circuit breaker. This sequence shall only be actuated if the following conditions are satisfied:

a) The loss of voltage is not due to a tripping of the incoming circuit breaker initiated by protection trip,

b) Voltage is detected on the other bus section,

c) There is not a simultaneous fault on both bus sections.

d) The system shall return to normal configuration using manual control.

9.2.17 A local load shedding will be implemented during loss (tripping) of one feeder distribution (transformer A or Transformer B) in a switchboard. In case of under voltage at one half bus bar, all necessary loads connected to this bus bar shall be shed according to a preset priority. This load shedding shall be initiated during the automatic transfer sequence in order to protect the electrical network from collapsing.

9.3 Transformers

9.3.1 Transformers design shall meet the requirements of the specification JERES P 121.

9.3.2 Transformers shall fully comply with the latest edition of IEC standards


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9.3.3 HV/HV transformers and HV/LV transformers shall be three phases oil immersed type transformers and LV/LV transformers shall be three phases Dry type.

9.3.4 The nature of windings of HV/HV, HV/LV and LV/LV transformers shall be copper.

9.3.5 Values of rated power of transformers shall be taken from the R10 series given in ISO 3 (1973) of preferred numbers: (…100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1000, etc.).

9.3.6 All HV/LV transformers shall be “hermetically sealed” tank type equipped with off-load tape changer with tapping range as follow on the HV side: (-5% /-2,5%/0/+2,5%/ +5%).

9.3.7 The connection diagram of HV/LV transformers shall be Dyn 11.

9.3.8 Cooling method of HV/LV transformers shall be ONAN.

9.3.9 HV/HV transformers rated 10MVA and above shall be equipped with conservator or expansion tank.

9.3.10 The conservator or expansion tank shall include a diaphragm or bladder in the auxiliary tank to prevent oil to air contact.

9.3.11 HV/HV transformers shall be equipped with detachable radiators isolated from the tank by means of ball valves.

9.3.12 Cooling method of HV/HV transformers shall be ONAN/ONAF from 10 MVA ONAN.

9.3.13 The connection diagram of HV/HV transformers shall be Dyn 11.

9.3.14 The HV/HV 380 kV / 34,5 kV transformers shall be provided with “On load tap changer”. The “On load tap changer” shall be managed to avoid more than 1 tapping position between the two transformers.

9.3.15 The tapping range of these transformers shall be as a minimum as follow and in any case shall be confirmed with the load flow studies: (± 10 % - 17 tapping position)

9.3.16 Cooling method of HV/HV 380 kV / 34,5 kV transformers shall be ONAN/ONAF.


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9.3.17 The connection diagram of HV/HV 380kV / 34,5kV transformers shall be YNyn 0.

9.3.18 Each power transformer shall be able to supply the total load of its downstream switchboard. Refer also to JERES-P-121.

9.3.19 Transformers for switchgear and controlgear shall support to be connected in parallel during the time needed by the automatic transfer of source sequence (1 second).

9.4 Uninterruptible power systems and DC systems

9.4.1 UPS and DC system design shall meet the requirements of the specification JERES-P- 103. Charger of UPS and DC system shall be sized to supply simultaneously full batteries charging and electrical loads. The boost voltage shall be limited to reduce the battery gas production.

9.4.2 DC power system shall consist of, but not limited to batteries, batteries circuit breaker, battery charger/rectifier, output distribution panel boards and management system.

9.4.3 UPS shall consist of, but not limited to batteries, batteries circuit breaker, batteries charger/rectifier, inverter, static transfer switch, manual bypass line, bypass shielded isolation transformer, output distribution panel boards and management system.

9.4.4 Batteries sizing: For applications involving a combination of continuous loads, non-continuous loads and/or momentary loads (such as switchgears), batteries shall be sized in accordance with the battery sizing worksheets of IEEE 1115 or equivalent IEC standards as applicable.

9.4.5 Battery back up time: The minimum battery back up times shall be in accordance with table as follow and shall be based on the rated power of the UPS:

Load location Type of load Primary power source Battery back up time

Instrument UPS for PIB and

MCB AC UPS Utility + Generator(1) 30 minutes

Remote AC & DC Solar photovoltaic 5 days (120 hours)

For HV and LV switchgear and

controlgear utility

DC Utility + Generator(1) 2 hours

1) Utility power supported by an emergency generator in case of loss of utility power.

9.4.5.1 For telecom Battery back up time: refer to telecom project specifications.

9.4.6 Battery installations

9.4.6.1 All batteries shall be installed in battery rooms or battery enclosure in accordance with IEC 50272-2. Batteries shall not be installed in enclosures inside a battery room.

Selection of battery installation type shall comply with following table:

Dedicated battery room Cabinet Outdoor battery box

Ni-Cd Vented type

(90-95 %)

R P (nota 1) P

Ni-Cd sealed type

(/95 %)

P R P (nota 2)

R: Recommended P: Possible

Nota 1: NiCd vented type battery shall not be installed inside cabinet inside electrical substation. They shall be installed inside dedicated battery room.

Nota 2: To be checked with Manufacturer according to environmental conditions.

9.5 Distribution boards

9.5.1 Distribution boards (e.g. for lighting and small power) shall be normally fed from only one feeder coming from one upstream board

Cells

Installation


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9.5.2 These distribution boards shall be fixed type

9.6 HVAC Distribution

9.6.1 Refer to corresponding JERES-K series.

9.7 Intertripping and Interlocking

9.7.1 Intertripping sequences and interlocking shall not be achieved via the Electrical Control System (ECS) but hardwired only.

9.7.2 Intertripping shall be provided where applicable between associated equipment to correctly isolate faulty items and to leave the system in a predictable orderly state after the operation of protection devices for instance normal opening or tripping by protection of an HV breaker shall cause the opening of the corresponding LV breaker.

9.7.3 Interlocking sequences shall not be implemented in the Electrical Control System (ECS) but hardwired only.

9.7.4 Interlocking shall be provided where applicable to prevent incorrect operation of equipment. This shall be achieved, depending on the particular equipment involved, either electrically or by a system or lock and key switches, for instance:

a) Mechanical interlock between the earth switch of the generator incomer breaker and the generator excitation control panel shall be provided.

b) Downstream breaker and bus tie breakers shall not be capable of closure until upstream breakers are closed.

c) Key interlocking shall be provided in order to prevent application of earthing devices until all sources of supply are isolated (access to transformer terminals, HV live parts in switchboard, etc.).

d) Mechanical interlocking shall prevent closing of an earthing switch on an energized part of an HV circuit.

9.8 Electrical Protection System


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9.8.1 Protective relaying system shall be applied throughout the power system to detect undesirable or intolerable operating conditions, and to disconnect the troubled areas or equipment from the other sections of the power system.

9.8.2 The design for the control and protection system shall provide as a minimum the following informations:

a) Relay and metering one line diagrams,

b) AC and DC schematic diagrams,

c) AC three lines diagrams,

d) Interconnection diagrams,

9.8.3 Protection system coordination studies shall be completed for all the power system installation. This study shall contain data and detail necessary to validate selection of the protective devices and instrument transformers used with the protection system.

9.8.4 Protection system coordination studies shall be performed using ETAP PowerPlot software.

9.8.5 The system coordination studies shall include:

a) A hard and electronic copy of protective system coordination study with all required setting parameters,

b) Recommended device settings,

c) Protective device data: manufacturer, style, model, type, range, and time characteristic curves. Protective device and plant data shall refer to the actual devices supplied on the project. General catalog extract or typical data are not acceptable, full manual are required.

d) Nameplate data and ratings of motors, buses, generators, power conductors, instrument transformers, power transformers, and cables (including cable short-circuit withstand limits).

9.8.6 Data for motors over 75kW (100HP) shall include the following:


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a) Power rating,

b) Nameplate voltage,

c) Full load current,

d) Locked rotor current,

e) Acceleration time at 80%, 90%, 100% ,

f) Permitted stall time at 80%, 90%, 100% and 110% rated voltage,

g) Thermal capability curves (hot/cold),

h) Number of start allowed, from cold in first hour and subsequent hours,

i) After a running trip, starts allowed in first hour and subsequent hours,

j) If acceleration time exceeds permitted stall time, data on speed switch and timers shall be provided,

k) RTD data.

9.8.7 Data for generators shall include: Rating, positive, negative and zero sequence impedances, negative sequence capability, minimum motoring power, over frequency curves, thermal capability curve, decrement curve, time constants.

9.8.8 The calculations, settings and coordination of the main or primary system protection shall be based on the following two operating conditions:

a) Normal minimum system,

b) Normal maximum system.

9.8.9 The coordination time interval between coordination pair of time-overcurrent relays shall be within the range of 0.35 to 0.50 second at normal maximum transient fault current.

9.8.10 The logic selectivity system shall be prohibited.


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9.8.11 The use of inverse overcurrent protection device shall be avoided as much as possible.

9.8.12 The maximum fault duration time allowed by the protection shall not exceed the short-circuit withstand capability of the protected equipment.

9.8.13 The calculations for subtransient fault current shall include the contribution from both synchronous and induction machines, while transient fault calculations shall include synchronous machines only.

9.8.14 Subtransient current values shall be used in calculating the settings and coordination of the following units:

a) instantaneous relays,

b) overcurrent relays with less than 0.1 second operating times,

c) Fuses with minimum-melting times less than 0.01 second.

9.8.15 Transient current values shall be used in calculating the settings and coordination of the following units:

d) Overcurrent relays with 0.1 second or more operating times,

e) Fuses with minimum-melting times of 0.01second or more.

9.8.16 The setting of instantaneous units that are sensitive to DC offset current shall be based on the maximum DC offset current in the protected circuit.

9.8.17 Whenever a backup protection is provided, it shall be set to protect against relay, breaker, or fuse failures.

9.8.18 Upstream backup protection shall coordinate with downstream protection over the range of normal minimum to normal maximum fault currents.

9.8.19 Where a local or remote backup protection is provided by the Saudi Electric Company (SEC), the SEC Electric System Protection Division shall be requested to provide backup protection and coordination with the new plant protection.


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9.8.20 The Contractor shall perform the design of the protection devices for the entire electrical network.

9.9 Electrical Control System (ECS)

9.9.1 General

9.9.1.1 Electrical Control System shall be considered to facilitate control, supervision and monitoring of the network.

9.9.1.2 ECS functions however should only be an aid to the operation of the network with the safety requirements being ensured by the normal direct acting devices (e.g. Protection relays acting on circuit breakers) which are themselves not linked to the ECS. In addition, the network shall remain in service should the ECS fail.

9.9.1.3 In case of ECS failure, basic functionality shall remain in operation (load shedding and automatic transfer sequences).

9.9.1.4 The ECS shall be in accordance with the specification JERES-P-127

9.9.1.5 Typical functions to be included in ECS are:

a) Control of power distribution e.g. remote open and close control facilities of the main circuit breakers of the HV and LV networks from the Control Room of the Refinery.

b) Provision of a VDU based system to provide animated display of power generation (if any) and distribution system, data acquired and provide operator/machine interface.

c) Event recording and parameter trending.

d) Display of alarms

9.9.1.6 Separate Oscilloperturbograph system shall be supplied at the 380 kV level.

9.9.1.7 ECS shall be implemented and be part of the DCS (Digital Control System).

9.10 Load Shedding


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9.10.1 Depending of the power distribution configuration and the load balance, a load shedding may be required. Refer to appendix A.

9.10.2 Loads to be shed shall be selected in accordance with Process and the load shedding priority sequence shall be manually configurable on each motor starter.

9.11 Motors

9.11.1 Motors design shall meet the requirements of the specification JERES-P-113. Electrical motors above 1000 kW shall be supplied with circuit breakers.

9.11.2 Motors shall fully comply with the latest edition of IEC standards.

9.11.3 Motors shall be of squirrel cage induction type unless otherwise specified by Company.

9.11.4 Motors shall be selected in accordance with table as follow:

Nominal system voltage

Motor nameplate

voltage

Number of phases

kW (HP) Type Notes

120 120 1 Up to 0.25 (0.34) - -

208 208 1 Up to 0.25 (0.34) - 1

208 208 3 0.18 (0.25) to 3.7 (0.5) Induction 1

480 480 3 0.18 (0.25) to 185 (250) Induction 2

4160 4160 3 185 (250) to 3000 (4000) Induction -

4160 4160 3 370 (500) to 3000 (4000) Induction

13800 13800 3 750 (1000) to 10500 (14000))

Induction 3

13800 13800 3 Above 10500 (14000) Synchronous 3, 4

Notes:


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1) 208V rating only for operation on 208V system. Note 1, shall follow the guidelines for 240V and 480V rated motors respectively.

2) Dual voltages 277/480V are only acceptable for motors up to 30 HP.

3) Above 1000kW (1340HP), the additional level of 6.6kV is permitted. The use of 6.6 kV motor plus unit transformer must be compared with a 13.8 kV motor on the basis of cost. The documentation shall be submitted to Company approval.

4) Could be asynchronous if available.

9.11.5 Motors for exposed outdoor installation shall be of the totally enclosed type and rated in accordance with IEC 60034-1 for ambient temperature as specified in JERES-A-105 and a “Class B” winding temperature rise.

9.11.6 The degree of protection of motors shall be at least IP 55 according to the IEC 60034-5.

9.11.7 Motors for indoor installation shall be totally enclosed or of the drip proof guarded type

9.11.8 The insulation system shall be “Class F” minimum.

9.11.9 Enclosures and terminal housings shall be metallic.

9.11.10 Fan shall be metallic or reinforced fiberglass, and shall be designed, depending the voltage, for dual rotation.

9.12 Lighting, Small Power and Welding Sockets

9.12.1 Lighting

9.12.1.1 Lighting design shall fully comply with the latest edition of IEC standards.

9.12.1.2 Lighting design shall meet the requirements of the specification JERES P 123.

9.12.1.3 Lighting system shall be split into three main systems:

a) Normal system : fed from normal distribution boards,


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b) Essential system: fed from essential distribution boards. The essential system shall consist of 30% of total installed lighting excepted for road lightings.

c) Emergency system: Selected luminaries of the above essential system, which illuminate escape routes, emergency exits and ladders, shall have an integrated Ni-Cd battery.

9.12.2 Socket Outlets

9.12.2.1 No socket outlet shall be provided inside process area.

9.13 Cables

9.13.1 Design of cables and wires shall be in accordance with latest edition of IEC standards.

9.13.2 Cable design shall meet the requirements of the specification JERES P 104.

9.13.3 As a general rule, the electrical cables shall be direct buried.

9.13.3 All cables shall be flame retardant type according to IEC 60332-3-22 (Category A).

9.13.4 In addition to this requirement, cables for special (vital safety) services (i.e. public address system, ultimate emergency distribution) shall also be fire resistant type according to IEC 60331.

9.13.5 The cables shall be able to ensure their service, under full load, in the climatic conditions prevailing on the site.

9.13.6 Aboveground cables shall be fixed on cable trays and may be exposed to sunlight, in which case they shall be armored, resistant to sunlight and be gas and steam tight.

9.13.7 Buried cables shall be armored and be resistant to aliphatic hydrocarbons. Cables passing through areas with risk of aromatic hydrocarbon infiltration shall be protected by a lead sealing sheath. In any case, absence of lead sheath shall always be justified by contractor and submit to Company for approval. All 380 kV and 34,5 kV power cables and associated control cables shall protected by a lead sealing sheath. All 4,16 kV cables coming from the emergency diesel generator shall be protected by a lead sealing sheath.


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9.13.8 Low voltage cables installed inside electrical substation shall be non-armored type, halogen free and be flame retardant.

9.13.9 Armor of multi core cables shall be galvanized steel wire type or double galvanized steel tape type.

9.13.10 Armor of single core cable shall be aluminum wires type or double aluminum tape type.

9.14 Cable Specification

9.14.1 Refer to specification JERMS-P-5502

9.14.2 Cable Sizing Criteria

9.14.2.1 The HV and LV cable sizing shall comply with the latest edition of IEC standards.

9.14.2.2 A cable sizing calculation note shall be issued by the Contractor during the Basic Engineering phase.

9.14.2.3 The calculation note shall provide all details for the appropriate selection of HV, LV power feeders, Motor feeders, AC and DC power and main lighting cables.

9.14.2.4 The minimum following requirements/parameters shall be taken into account when performing cable sizing:

a) Site conditions:

b) Ambient conditions (soil/air temperature, soil resistivity, etc.),

c) Type of installation, above head, underground, depth of laying, number of layers, exposition to sun radiation, etc.

d) Network characteristics (voltage, number of phases, neutral system IT, TN, TT, TN-S, TN-C, distributed neutral or not, etc.)

e) Cable type (armored, non armored, single core, multicore, etc.)

f) Cable current carrying capacities according to the standard conditions,


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g) Cable current carrying capacities according to the site conditions (derating factor based on site conditions),

h) Type of load to be fed,

i) Steady state condition voltage drop,

j) Motor starting voltage drop,

k) Fault level of system (according to switchgear fault rating),

l) Maximum permissible fault duration,

m) Type and setting of overload and short circuit protection with respect to the neutral system,

n) Prospective and maximum permissible touch voltage when applicable,

o) Harmonic level.

9.14.2.5 Ambient Conditions: The main ambient conditions to be taken into account are defined in this present standard.

9.14.2.6 Site Installations: The main general rules for the cable routing (above ground, on trays/ladders, directly buried, buried in duct, etc.) is defined in the particular specification n° JERES-P-104, however, its remains the Contractor responsibility to ensure that the appropriate parameters (number of layers/ladders/spacing between ladders, cables, number of cables layers, etc.) are suitable taken into account when evaluating the site conditions derating factors.

9.14.2.7 Network Characteristics: The network characteristics shall be carefully reviewed to identify the specific sizing criteria to be performed/checked. In particular, the neutral system, the distribution or not of the neutral and relevant overload and short circuit protection shall be identified to ensure that the final cable selection provide the appropriate personal and electrical equipment protection.

9.14.2.8 Cable Current Carrying Capacities and Derating Factors: For the definition of site cable current carrying capacities, the Contractor shall first refer to the cable rated


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characteristics as provided in the relevant standards and then apply the appropriate derating factors to account for the site conditions.

9.14.2.9 Cable current carrying capacities: The Contractor shall first refer to the cable rated current carrying capacities listed in the relevant standards:

a) IEC 60364-5-52 for the LV installation

b) IEC 60183 for the HV installation

9.14.2.10 Derating factors: The following site conditions/parameters shall be carefully reviewed so as to determine the final overall derating factor that shall be applied on cable standard rated current carrying capacities.

a) Ambient conditions: air/soil temperature,

b) Soil resistivity,

c) Depth of installation when underground

d) Laying and grouping factors,

e) Sun radiation,

f) Hazardous areas (derating factor = 0.85)

g) Parallel cables for same circuit,

h) Harmonic level for specific loads and cases.

9.14.2.11 The Contractor shall provide all details for the definition of the overall derating factor. As a minimum, Standards derating factor tabulation references shall be provided; copy of these tabulations may also be attached with the calculation note. All site conditions that may be encountered shall be carefully addressed and the relevant site current carrying capacities assessed.

9.14.2.12 For cables routings through different conditions (above ground, underground, etc.) the most stringent one shall be used for the final cable selection.


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9.14.2.13 Voltage Drop: The section 7 of the present standard shall apply for the maximal steady state and transient operation voltage drop within the cables. The Contractor shall clearly define in the calculation note the voltage drop and formulae that are used.

9.14.2.14 Overload and Short Circuit Withstand: The Contractor shall evaluate the cable overload and short time thermal withstands capability based on:

a) Neutral system,

b) Maximum permissible fault duration,

c) Overload protection,

d) Short circuit protection (fuses or circuit breaker characteristics, relay setting and operating time)

e) Fault level of system (based on calculated value in accordance with prescription of paragraph 8.3.4),

f) Cable characteristics (conductor and insulation type, etc.) and relevant permanent and maximum admissible conductor and insulation temperature.

9.14.2.15 As a reminder, the protection tripping time shall be defined in accordance with the preliminary protection coordination study.

9.14.2.16 Basically, final feeder (such as motor feeder) may be sized based on 100 to 150 ms protection tripping time. For upstream cables, (network or power generation cables) a minimum tripping time of 1 sec shall have to be considered.

9.14.2.17 This evaluation will allow for the definition of a minimum cable cross section as well as a maximum cable length to allow for:

a) Suitable cable withstand to fault conditions,

b) Suitable protection device trip/operation within the acceptable permissible fault duration.

9.14.2.18 The full calculation details (formulae and samples) shall be provided for review.


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9.14.3 Prospective and Maximum Permissible Touch Voltage

9.14.3.1 The prospective and maximum permissible touch voltage shall be calculated and carefully taken into account when applicable since it implies personal protection against direct and indirect contact when a first or even second fault occurs.

9.14.3.2 These calculations shall be implemented according to the relevant IEC standards and mainly based on:

a) Neutral system,

b) Maximum permissible fault duration

c) Short circuit protection (fuses or circuit breaker characteristics and earth leakage relay when implemented)

d) Cable characteristics (presence or not and cross section of a protective conductor.

9.14.3.3 This calculation shall allow for the definition of a minimum cable cross section as well as a maximum cable length to allow for:

a) Suitable cable withstand to fault conditions,

b) Suitable protection device trip/operation within the acceptable permissible fault duration.

9.14.3.4 The full calculation details (formulae and samples) shall be provided for review.

9.14.4 Cable Sizing Calculation Note – Documentation

9.14.4.1 The calculation note shall address all details and criteria mentioned in previous sections for the appropriate selection of:

a) All HV cables,

b) All LV power feeder cables,

c) Typical motor feeder cables (selection chart)

d) AC and DC power cables (selection chart)


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e) Lighting cables (selection chart).

9.14.4.2 HV cables

9.14.4.2.1 All the detailed calculations for each HV cable (distribution cables or captive transformer motor cable) shall be provided.

9.14.4.2.2 All cable current carrying capacities as well as all derating factors for the different site ambient and installation conditions shall be clearly listed and identified.

9.14.4.2.3 Tabulation shall summarize for each HV cable all the calculation criteria and shall define the final selected cable type and cross section.

9.14.4.3 LV cables

9.14.4.3.1All the detailed calculations shall be provided for each LV power distribution cables as:

a) Transformer secondary cables,

b) Transformer feeder

c) Main distribution feeder between MCC,

d) EDG incomer,

e) Etc.

9.14.4.3.2All cable current carrying capacities as well as all derating factors for the different site ambient and installation conditions shall be clearly listed and identified.

9.14.4.3.3Tabulation shall summarize for each HV cable all the calculation criteria and shall define the final selected cable type and cross section. All protection devices characteristics that have been considered shall be provided.

9.15 Emergency Diesel Generator (EDG)

9.15.1 One service diesel generator shall be foreseen in 380 kV distribution substation (SS1). Emergency diesel generators shall be foreseen distribution substation SS 11, SS 12,


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SS16, SS 1601, SS 1603, SS 1606 and SS 1612 sized in accordance with emergency loads to be supplied.

9.15.2 The emergency diesel generator of one main distribution substation shall be designed for supplying the emergency loads of the downstream substations connected to this main distribution switchgear.

9.15.3 The equipment shall be designed to operate in an environment and a site’s climatic conditions defined in section 4 of this standard.

9.15.4 The equipment shall be installed in a dedicated room attached with the substation building. This EDG room is not air-conditioned, but provided with forced ventilation. In such circumstance, the equipment shall withstand, without damage and performance derating, an ambient temperature as defined in JERES-A-105.

9.15.5 The auxiliary equipment of the EDG (lubricating, cooling…) shall be directly supplied from the emergency controlgear.

9.15.6 Moreover, the air inlet of diesel generator shall be designed taking into account the following data:

a) The normal airborne dust concentration shall be considered as 1mg/m3

b) During sand storm conditions, dust concentrations reaching 500 mg/m3 are encountered and winds may gust to 112 km/h.

c) 95% of all dust particles are less than 20 micrometers and 50 % of all dust particles are less than 1.5 micrometers in size.

d) Compounds present in the dust include those of sodium, calcium, magnesium, silicon and aluminum. When wetted (100 % humidity conditions), these compounds function as electrolytes and can results in severe corrosion of materials. Other pollutants present (ppm in vol/vol in atmosphere, worst case) are H2S (5ppm), SO2 (5ppm), CO (100ppm), NOx (5ppm) and hydrocarbons (50ppm).

9.15.7 All equipment shall be protected from these contaminants to prevent corrosion and operational failure.


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9.15.8 In addition to the above requirements, equipment installed near shore (i.e. within 1 km from the shoreline) shall also be protected against failure due to wind-borne seawater spray and the accumulation of wetted salt (NaCl).

9.15.9 Diesel generator set shall not generate noise in excess of 85 dBA at a distance of 1 meter from the enclosure taking into account the fact the is considered to be immediately outside the walls and ceiling within which it is installed.

9.15.10 The Diesel Generator set comprises as minimum the following elements:

a) a shaft assembly comprising a diesel engine and a 3 phases generator,

b) an Emergency Diesel Generator panel (EDG Panel),

c) an EDG On Load Test panel (OLT panel), having a set of three resistors banks provided for external installation,

d) all the auxiliary equipment and accessories required.

9.15.11 The rated voltage of the Emergency Diesel Generator set shall be defined according the following data:

a) The total load to be supplied,

b) The total load to be supplied in each downstream substation,

c) The maximum distance between the main distribution substation and the downstream substations.

9.15.12 Basic Data

9.15.12.1 The diesel generator set and the associated components shall be selected such as to guarantee a minimum operating of 20 years, assuming a maximum use of 10 hours continuous duty and 100 hours per year.

9.15.12.2 The diesel generator set is inoperative under normal operation conditions, but must be ready to start up and to supply its rated power. The total time for starting and taking over 100% of the load shall not exceed 15 seconds in the worst case conditions.


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9.15.12.3 The emergency diesel generator set shall be considered as a stand alone and autonomous package. As such, it shall be capable of generating its own power supply required for the control circuits and the auxiliary equipment needed for its automatic operation. It shall also include the battery charger and the start batteries if an electrical starting system is adopted.

9.15.12.4 The combustion air required for the diesel engine shall be drawn from the roof of the building.

9.15.12.5 The hot combustion gases shall be discharged outside the building.

9.15.13 Operating Mode

9.15.13.1 Automatic Starting: The emergency diesel generator set is designed to feed the emergency loads. All the generator set’s monitoring and control devices (except for pressure and temperature indicators) shall be grouped on a control panel located near to the set (marked EDG panel). Starting shall normally be automatic and controlled by a relay-based control panel installed in the electrical substation. Stopping of the emergency generator set is initiated locally from the EDG panel.

9.15.13.2 Manual Starting: Start and stop command may be given from the EDG panel, in particular for periodic diesel generator set tests. The diesel generator set shall be tested, under load, by feeding the resistors banks. The procedure for these tests shall be simple and require the presence of only one operator. The frequency of the tests should be as follow:

a) a weekly test at 100% of load, during 15 minutes,

b) a monthly test at 100% of load, during 1 hour.

9.15.14 Technical Requirements

9.15.14.1 Diesel Engine: All the auxiliary equipment for the emergency diesel generator set required for its use shall be provided by the Manufacturer of the package. The emergency diesel generator set shall be provided with a redundant starting system which shall be capable of six consecutive starts. The minimum equipment shall be supplied:

a) cooling system,


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b) lubrication system,

c) oil and water circuit preheat devices,

d) fuel day tank with automatic filing from main fuel tank,

e) main fuel tank, designed to be buried outside the building,

f) starting system (dual source for starting),

g) fuel supply circuits,

h) combustion air intake circuit,

i) combustion gas exhaust circuit,

j) the generator coupling and its protective cover,

k) the common frame for the engine and the generator,

l) anti vibration damping devices,

m) emergency diesel generator control panel (EDG panel),

n) On load test panel (OLT panel).

9.15.14.2 Generator: The generator shall comply with the latest edition of IEC standards. The generator design shall meet the requirements of the specification JERES-P-113. The generator type shall be without slip ring or brushes, with excitation generated by a reverse alternator mounted at the end of the shaft. The main characteristics of the generator are as follow:

a) Rated voltage : 4.16 kV

b) Coupling : Star, neutral point output,

c) Frequency : 60Hz,

d) Number of poles : 4


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e) Insulation : Class F

f) Heating Class : B

g) Degree of protection : IP 55,

h) Coolant : air

9.15.14.3 The generator shall be designed to be capable of supporting:

a) a 10% overload during 1 hour and a 50% overload during 1 minute without exceeding the Class B heating limits,

b) 3 phases short circuit with a level of 3xIr (rated current) during 3 seconds.

10 Electrical Substations

10.1 General

10.1.1 Electrical distribution equipment shall be installed within dedicated electrical building (Refer to JERES-P-119). Outdoor installation shall be avoided and be subject to Company written approval.

10.1.2 The associated power transformers shall be located outside in separated bays adjacent to the electrical room.

10.1.3 The number and location of substations and associated transformers shall be determined according to the following criteria:

a) installation shall be as near as possible to the loads,

b) installation shall be outside hazardous areas,

c) Transformers shall be dedicated to a single process areas,

d) Dimensions of substations shall enable easy and safe operation and maintenance,

e) Substations shall be built from concrete and be capable to be extended at each end.


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10.1.4 The construction type of electrical substations is blast resistant.

10.1.5 Only authorized personnel shall enter into the electrical substations.

10.1.6 Electrical rooms shall be air conditioned to provide clean and dry environment (ambient air temperature inside substation is 25°C61°C).

10.1.7 Room pressurization shall be provided against sand wind and/or dusty atmosphere.

10.1.8 The layout in the room shall be governed by the size and quantity of switchgears and a reservation shall be made for extensions (e.g. at least 20% extra space to be provided for future phases unless otherwise specified).

10.1.9 For HV and LV switchgear and controlgear, available space for 20% of the total length of the switchboard with at least a minimum of one cubicle at each side.

10.1.10 The layout will provide safe access and adequate space for operation, maintenance and removal of each item of equipment.

10.1.11 Doors shall be provided such that an unobstructed exit route is available in case of emergency. The maximum distance to be crossed inside the substation to reach an exit is set at 15 meters.

10.1.12 One door shall be sized to allow entry of the largest single item of equipment. Building shall be designed with technical void (cable vault with minimum height of 2m under beams) for cable routing. Cable penetration in the buildings shall be by adequate sealing method. Spare penetration for temporary and future cables shall be provided.

10.1.13 Typical requirements for electrical buildings are as follow:

a) 1 electrical room,

b) 1 battery room, if necessary depending on battery type

c) 1 HVAC room,

d) 1 Technical vault

e) Transformer bays


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10.1.14 The main 34.5kV distribution substation shall be composed with:

a) 1 electrical room for each section of 34.5 kV bus bar,

b) 1 electrical room for LV switchboard,

c) 1 room dedicated to the emergency diesel generator,

d) 1 battery room, if any

e) 1 HVAC room,

f) 1 Technical vault

g) Transformer bays

10.1.15 The 380 kV / 34.5 kV transformers shall be installed in transformers bays of the 34.5 kV distribution substations (SS 11 – SS 12 and SS 16).

10.1.16 Cable trays and cable ladder shall be used for cable routings in technical vault.

10.1.17 Floor finishing shall be designed for rolling of the heaviest load (circuit breaker on its truck, etc.) and tolerance (floor flatness shall be in accordance with switchgear manufacturer requirements).

10.1.18 Floors shall be coated with anti dust coating.

10.1.19 Electrical rooms with concrete walls and ceiling shall be painted.

10.1.20 In all cases no pipe shall be accepted within electrical rooms. In all cases, HVAC duct shall not be installed above electrical switchgear or controlgear.

10.2 Minimum clearances in substations

10.2.1 Following figures are minimum values given as a general guidance, unless otherwise specified by equipment/switchgear manufacturer (especially for pressure relief in case of arc resistant switchgear).

Minimum clearance


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Vertical from equipment to ceiling beams and/or HVAC ducts 450 mm

Front of operating side of high voltage switchgear 2000 mm

Front of operating side of low voltage switchgear 1500 mm

Switchgear (including available space for extension) from each end and non operating side

1000 mm

Front of operating side of low voltage distribution board/panels

1000 mm

Neutral grounding resistor, at least an 3 sides 1000 mm

10.3 380 kV GIS Substation

10.3.1 The main 380kV electrical building has special requirements as follow:

a) 1 electrical room for each section of 380kV GIS switchgear,

b) 1 electrical room for LV switchgears

c) 1 electrical room dedicated to SEC interfaces,

d) 1 battery room if necessary depending on battery type

e) 1 HVAC room,

f) 1 Technical Vault

g) Transformer bays

10.3.2 Mesh Earthing to minimize the voltage step: Due to the high earth fault current, special care shall be taken to design the earth mesh network for a building receiving a GIS switchgear (refer to specification n° JERES P 111).

10.3.2.1 The building earthing network design shall be reviewed and approved by the GIS manufacturer before installation.


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10.3.2.2 The purpose of this additional requirement is to minimize the voltage step.

10.3.2.3 Joints and overlaps in the concrete reinforcing mesh shall be welded to provide good electrical continuity. The minimum is one weld every two crossing points.

10.3.2.4 The mesh shall be connected to the earthing network by a minimum of two points.

10.3.2.5 The mesh shall be designed with squares smaller than 20 cm large.

10.3.3 Crane

10.3.3.1 An overhead crane shall be installed in the GIS room to be used during equipment installation and maintenance.

10.3.3.2 The design shall de reviewed and approved by the GIS manufacturer before installation.

10.3.3.3 The manual control command shall be easily accessible even when there are bus duct across the way.

10.3.4 SF6 Leak detection

10.3.4.1 The room building containing GIS shall be equipped with a SF6 leak detection system.

10.3.4.2 Detectors shall be installed in the lowest part of the building.

10.3.4.3 A remote alarm shall be sent to the control room.

10.3.4.4 At the door entrances, flashing lights shall be provided.

10.4 Transformers installation

10.4.1 Transformers shall be installed close to the substations which they feed.

10.4.2 Oil immersed transformers shall be located outdoor.

10.4.3 Dry type transformers shall be located indoor and inside cable vault.


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10.4.4 Oil immersed transformers shall be separated from each other by walls and shall be protected against direct sun rays by a removal roof. Roof shall ensure natural transformer ventilation.

10.4.5 A receiving pit shall be built in each transformer and shall be connected to the oily water system via a fire break valve.

10.4.6 Minimum clearance for transformer connections shall be 1000 mm (cables not included) and 1000 mm for the other sides.

10.4.7 Access to transformer bays shall be obtained via a lockable-screened door.

10.4.8 Neutral earthing resistances shall be located in safe area and as close as possible to the transformers.

10.5 Battery installation

10.5.1 Battery shall be preferably installed into electrical room inside cabinets.

10.5.2 Selection of battery installation type shall comply with table in section 9.4.6.1.

10.5.3 When required, a circuit breaker with overcurrent protection and undervoltage tripping coil shall be provided for ESD purpose. It shall be in an explosion proof enclosure located close to each battery. “Reset” of this breaker shall be possible by an “externally accessible” operating handle.

10.5.4 As batteries might release hydrogen, dilution ventilation shall be provided in the room containing battery cells.

10.5.5 Facilities shall be provided to inhibit the charge mode in case of ventilation system failure and revert to float mode.

10.5.6 For recombination batteries with recombination ratio as minimum equal to 95% with chargers fitted with charging current limitation, batteries may be installed in standard electrical room and/or standard technical room with no hydrogen detection.


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Appendix A

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JERES-P-100 Basic Power System Design Criteria

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Transcript of JERES-P-100 Basic Power System Design Criteria