Electrical Spec _site 26 Sep 2010_ Oct 10 (4)

Volume II: Section D1: Table of Content

TOC - i

Table of Content . ELECTRICAL ............................................................................. 1

1.1 Introduction........................................................................................................... 1

1.2 Design guide lines ................................................................................................ 1

1.3 Power system studies ........................................................................................... 2

1.3.1 General ................................................................................................ 2 1.3.2 Type of studies ..................................................................................... 2

1.4 Generators ........................................................................................................... 3

1.4.1 Cooling and Ventilating System ............................................................ 3

1.5 Generator Condition Monitoring and Diagnostic System ...................................... 4

1.6 Excitation system and equipment ......................................................................... 5

1.6.1 Automatic Voltage Regulator (AVR) ..................................................... 6

1.7 Generator main connections and neutral earthing ................................................ 8

1.7.1 General ................................................................................................ 8 1.7.2 Design .................................................................................................. 8 1.7.3 Conductors, flexible connections, joints and disconnecting links .......... 9 1.7.4 Enclosures and insulators .................................................................... 9 1.7.5 Pressurization ..................................................................................... 10 1.7.6 Earthing of main connections and connected plant and equipment .... 10 1.7.7 Supporting structures and wall seals .................................................. 10 1.7.8 Termination enclosures ...................................................................... 10 1.7.9 Voltage transformer cubicles .............................................................. 11 1.7.10 Neutral earthing .................................................................................. 11 1.7.11 Generator switchgear ......................................................................... 12 1.7.12 Sulphur hexafluoride (SF6) ................................................................. 13

1.8 Transformers ...................................................................................................... 13

1.8.1 General .............................................................................................. 13 1.8.2 Station auxiliary transformers ............................................................. 14 1.8.3 Oil filled transformers .......................................................................... 14

1.9 Switchgear.......................................................................................................... 16

1.9.1 General .............................................................................................. 16 1.9.2 MV switchgear .................................................................................... 18 1.9.3 LV switchgear ..................................................................................... 19

1.10 Current transformers .......................................................................................... 20

1.11 Voltage transformers .......................................................................................... 21

1.12 125V DC supply system ..................................................................................... 21

1.13 UPS system ........................................................................................................ 22

Volume II: Section D1 : Table of Content

TOC - ii

1.14 Protection ........................................................................................................... 23

1.14.1 General .............................................................................................. 23 1.14.2 Generator protection ........................................................................... 23 1.14.3 Generator excitation system ............................................................... 24 1.14.4 Generator transformer protection ....................................................... 24 1.14.5 380kV cable protection ....................................................................... 25 1.14.6 Dry type transformer protection .......................................................... 25 1.14.7 MV Motor Protection ........................................................................... 26 1.14.8 LV Motor Protection ............................................................................ 26

1.15 Synchronizing ..................................................................................................... 26

1.16 Metering ............................................................................................................. 26

1.17 Motors ................................................................................................................ 27

1.18 Variable speed drives ......................................................................................... 27

1.19 Earthing .............................................................................................................. 28

1.20 Lightning and surge protection ........................................................................... 31

1.21 Cable & Cable Installation .................................................................................. 31

1.21.1 General .............................................................................................. 31 1.21.2 EHV cables ......................................................................................... 32 1.21.3 Medium voltage cables ....................................................................... 32 1.21.4 Low voltage cables ............................................................................. 32 1.21.5 Continuous and fault current carrying capacity ................................... 32 1.21.6 Instrumentation and control cables ..................................................... 33 1.21.7 Optical fibre cables ............................................................................. 33 1.21.8 Telephone cables ............................................................................... 33 1.21.9 High temperature cables .................................................................... 33 1.21.10 Thermocouple and compensating cables ........................................... 34 1.21.11 Intrinsically safe cables ....................................................................... 34 1.21.12 Mineral insulated cables ..................................................................... 34 1.21.13 Cable installation ................................................................................ 34

1.22 Electrical equipment for hazardous areas ........................................................... 36

1.24 Interfaces with substation ................................................................................... 40

1.25 380kV overhead/underground cable works associated with integration of new steam generation units at PP10 ....................................................................................................... 41

1.26 Protection requirements for the integration of new steam units at PP10 ............. 42

Volume II: Section D1 : Electrical System Description

Page 1 of 42

1. ELECTRICAL

1.1 Introduction This part of the Specification details the requirements for the electrical plant for the steam

turbine generating units to form the conversion to combined cycle of the existing simple cycle generating units and the criteria against which the equipment will be designed.

CCGT Contractor shall undertake the electrical systems studies, including protective relay co-ordination studies, with the existing relays supplied by SCGT Contractor (GT units and its associated Balance of Plant) and submit calculations to demonstrate that the selected material and equipment are rated adequately for making the connection.

CCGT Contractor shall be responsible for liaising with SCGT Contractor and Company (SEC) to obtain any details and information necessary to allow for the design, build and commissioning of the HRSG, Steam turbine generating units, ACC, and balance of plant electrical systems and associated auxiliary equipment including connection to equipment supplied by SCGT Contractor and the Company (SEC).

1.2 Design guide lines The failure of any one part of the electrical ac and dc auxiliary system shall not cause any

loaded generator to trip. The system design shall have a level of security appropriate for meeting the demands of the SEC system. The design of the auxiliary system shall also include reserve capacity that is appropriate to the plant and equipment supplied.

The rating of the electrical equipment shall take into account the future installation of TIAC.

Where electrical equipment is essential to the continued running of the installation, the associated auxiliary systems shall be arranged so as to allow recovery from fault conditions and also to permit inspection and maintenance of equipment to be carried out without interference with the normal operation of the plant.The essential supplies systems shall be capable of maintaining the supply to all instruments, controls and auxiliaries required for the safe and reliable operation of the plant and equipment under all normal and abnormal operating conditions including, where necessary, satisfactory shut down and the placing of the steam turbines onto barring gear following the loss of the connection to the transmission system. The design shall require only minimal operator intervention to restart the auxiliary systems upon restoration of the connection.

The electrical plant and equipment shall be provided with suitable means for electrical disconnection, isolation and earthing of connections to facilitate maintenance.

CCGT Contractor shall be responsible for liaising with the Engineer and the Company (SEC), to ensure the Emergency Diesel Generators and the Station Emergency tie in line from the SCGT station board is sized to consider the running of at least one instrument air compressor on each block during a station black out.


Page 2 of 42

The auxiliary power supplies systems and associated switchgear shall include a comprehensive interlocking scheme to ensure safety of personnel. This shall be co-ordinated with that supplied by SCGT Contractor to form an integrated scheme. In addition to the requisite operational interlocking, the switchgear shall be designed to incorporate a system of isolation and locking such that when an authorized person isolates a circuit he can lock it off and make safe.

Any difference or deviations in specification between this electrical system description and SEC spefications shall be clearly identified in Volume IV, Section A, Schedule FF which shall be completed and returned as part of the Tender.

The design of the electrical power systems shall be based on the concept indicated on the single line diagram, Drawing No 162749/PBP/0021.

1.3 Power system studies

1.3.1 General CCGT Contractor shall submit calculations to demonstrate that the electrical plant

equipment is adequately rated.

These calculations shall assume ‘worse case’ values of positive phase sequence impedance for all generators, cables and transformers. For fault level studies, transformer impedances shall be based on the lowest transformation ratio tapping taking into account the limit of permissible tolerance on this value. CCGT Contractor shall clearly state the basis for the value of motor fault current contribution.

CCGT Contractor shall be responsible for liaising withthe Engineer and the Company (SEC) to obtain the necessary input data from the SCGT studies for the CCGT system study calculations.

1.3.2 Type of studies The types of studies to be undertaken are as follows:

i. Power flow studies shall be carried out to ensure adequate thermal rating of the plant and equipment and acceptable voltages at every point in the system. Optimum transformer tappings shall be determined.

ii. Fault level studies shall be carried out to ensure adequate short circuit rating of the plant and equipment.

iii. Dynamic studies shall be carried out to ensure satisfactory motor starting with an acceptable level of voltage drop.

iv. Harmonic studies shall be carried out to ensure voltage and current THD are in acceptable level.


Page 3 of 42

1.4 Generators The generators shall comply with the requirements of IEC 60034-3 and shall be of an

established design having a proven record of reliability for similar applications.

The generators shall be cooled by air in a closed circuit arrangement incorporating integral air to water heat exchangers, or hydrogen cooled. The cooling water for the generators shall be supplied from a closed circuit system, the requirements of which are detailed elsewhere in the Specification.

The base capability of each generator shall comply with the requirement of IEC 60034-3 over the full specified operating range of air temperature at site.

Each generator shall be capable of generating rated active power over the range of power factor from 0.8 lagging to 0.95 leading.

The short circuit ratio shall be not less than 0.5.

The stator and rotor insulation systems shall be to Class 155 (F) in accordance with IEC 60085 but the relevant temperature rises and total temperatures shall not exceed the limits for Class 130 (B).

All six terminals shall be brought out of the machine and shall be available for external connection to the main isolated phase bus ducts (IPBs) and bus ducts to the neutral earthing transformer.

Shaft earthing of the generator shall be provided, together with the means of monitoring shaft voltages and bearing insulation.

If air cooled generators are provided thermostatically controlled anti-condensation heaters shall be fitted, complete with isolating switches and indicating lamps. Appropriate warning notices shall be fitted. The heaters shall be switched on and off automatically; off when the generator is in service and on when it is out of service.

In designing the layout of the plant particular attention shall be given to ensuring free access for the complete removal and reinstatement of the generator rotor. It shall also be possible to remove and reinstate the generator stator with the minimum disruption to adjacent plant and equipment. Any special equipment necessary for rotor and stator handling, including jacks, slings, lifting beams, skids, shaft extensions for assembling and dismantling shall be provided.

1.4.1 Cooling and Ventilating System

For water-cooled generator, the cooling of the generator cores, windings, etc. heated up under operation, shall be performed by totally enclosed water air cooling (TEWAC) system. For exciter area, filtered natural air circulation systems shall be provided subject to the approval of COMPANY Engineer.


Page 4 of 42

Two resistance thermometers shall measure the high and low points of temperature of the cooling medium and temperature alarm shall be provided.

For hydrogen cooled generators, a generator hydrogen cooling system shall be provided along with a CO2 purging system. Gas monitoring together with seal oil and control apparatus shall also be provided.

1.5 Generator Condition Monitoring and Diagnostic System Each generator shall be provided with equipments for continuous on-line condition

monitoring of the stator windings insulation systems and for rotor winding earth fault conditions.

A diagnostic system shall be provided to continuously monitor and record the generator condition and possible deterioration. The system shall collect record and analyze machine parameter and data required for early detection of changes of the generator condition and shall ease rating of the stress of main components with the aim to enable condition dependent preventive maintenance. The on-line condition monitoring equipment shall be compatible with plant DCS system for plant operator to have full access on the condition of the generator in Main Control Room. The main features shall include:

i. Fault detection with early pre-alarm and alarm.

ii. Partial discharge monitor.

iii. Air gap flux probe equipment for detection of interturn shorts in the rotor winding.

iv. On-line diagnostic

v. Data storage/ recording

vi. Data base for expert assessment

The generator condition monitoring and diagnostic system shall cover the stator core end winding vibration, rotor, bearings, cooling air analysis if appropriate, seal oil if appropriate, partial discharge, structure borne sound analysis, vibration diagnostic,.

Resistance temperature detectors shall be installed as follows:

• Indirectly cooled stator windings (embedded type detector) 3 per phase

• Cold air from coolers 1 per path

• Warm air to coolers 1 per path

• Cold water to coolers 1 per path

• Warm water from coolers 1 per path


Page 5 of 42

Dual type temperature detectors shall be provided in the bearing metal and outlet oil connection on each generator bearing.

Flexible type leads from temperature detectors shall be brought out in a safe manner to metal clad terminal boxes fitted in accessible positions on the outside of the generator casing. Each terminal box shall be fitted with a label enabling each individual detector to be readily identified.

Remote indication shall include stator and bearing temperatures, bearing oil flow, bearing vibration, liquid in casing. Local indication shall include bearing oil temperatures and flow.,

1.6 Excitation system and equipment The generators shall be of brushless excitation system, digital voltage regulator and

associated accessories as follows:

The brushless excitation shall be consists of a high frequency AC generator complete with rotating, series redundant diode assembly and lead assembly that connects DC diode output to the field windings of the main generator.

The exciter mounting shall be overhung, quill mounted on the generator shaft.

Field poles shall be made of high steel laminations with coil insulation of class F and impregnated insulation (VPI).

The stator assembly shall consist stationary field poles mounted on steel housing. The steel housing shall have a base to allow floor mounting of the exciter stator assembly.

The full wave, 3-phase bridge diode assembly shall rectify the exciter armature output. The diode shall be mounted in spring loaded clamp assembly in a radial direction so that centrifugal forces aid in providing proper clamping force at operating speed.

A field ground detector shall be mounted in exciter rotor.

Each generating unit shall be equipped with high response Excitation System with continuously acting Automatic Voltage Regulation (AVR) System with no dead bands. The AVR shall be designed and operated to maintain the steady-state terminal voltage within ± 0.5 per cent of the set point in the normal voltage range without instability over the entire operating range of the Unit. The regulator shall have dual automatic channels together with manual control facilities for commissioning and maintenance. An auto following control function shall be provided to ensure smooth transfer between automatic channels. The voltage reference signals for the two automatic channels shall be provided from separate sets of VTs. Local and remote set point control shall be provided for automatic control, with local control provided for manual operation. Appropriate auto/manual changeover facilities shall be provided.

Field suppression equipment shall be provided to rapidly reduce the excitation of the generator to zero in response to a trip signal or a circuit breaker open signal. The field suppression


Page 6 of 42

equipment shall operate independently from the excitation control equipment. It shall be housed in a cubicle and form part of the excitation equipment cubicle suite.

1.6.1 Automatic Voltage Regulator (AVR)

The automatic voltage regulator including the equipment for hand control shall be mounted in a separate cubicle. The cubicle shall be installed in Local Control Room or in air-conditioned room.

The control system shall employ a fast response continuously acting electrical regulating device, which shall be responsive to the average value of the three generator phase voltages and to any other signal necessary to maintain steady state and transient stability.

The regulating equipment shall be free from voltage drift and insensitive to frequency variations between 57 and 62.5 cycles per second and shall maintain the generator terminal voltage within ± 0.5 per cent of the pre-set value over the whole load range of the generator.

When the generator is subjected to a sudden loss of the maximum continuous output at rated power factor, the equipment shall be capable of limiting the generator transient over-voltage to a value not exceeding 110 per cent of the rated voltage and shall restore the voltage up to a maximum deviation of 2 per cent of the nominal pre-set value within three (3) seconds.

The equipment shall be complete with all selector switches, changeover switches, indicating instruments, resistances, rectifiers, fuses, indicating lamps to ensure that in the event of a component failure of the automatic system including fuse failure, the excitation circuit is automatically switched over from automatic to manual control.

Furthermore, the control and excitation system is to be provided with:

i. Quadrature droop parallel running compensation (adjustable 0-10 per cent)

ii. Under-excitation or load angle limitation with adjusting device

iii. Time-graded limitation of the maximum excitation current.

iv. Maximum volts per hertz limiter.

A voltage reference adjuster shall be included in the control circuit being capable of adjusting the voltage between 80 and 110 per cent of the rated voltage under all permissible load conditions and to keep this value automatically constant during operation of AVR.

For manual adjustment of the generator voltage, a similar control device shall be provided to adjust the excitation so as to start with about 10 per cent of the generator no-load voltage up to 110 per cent rated voltage. Moreover, this device must have sufficient fine control between 90 and 110 per cent of the generator no-load voltage to ease manual and automatic synchronization. The manual voltage control (MVR) shall be free from hunting.


Page 7 of 42

The manual and the automatic control system shall follow accurately the operating equipment to prevent the increase or decrease in excitation upon transfer from automatic to manual control, or vice versa.

For local control, following elements shall be provided on the AVR cubicle:

A. Delta V (AVR/MVR) indication

B. Set point indication

C. Set point adjuster raise/lower for AVR/MVR

D. Change-over switch AVR/MVR

E. Alarm table (approx. 15 alarms/indications)

F. Key-locked local/remote/off selector switch.

The system supply shall be completely coordinated, reliable and proven, including all necessary functions of control, protection and alarm customarily required for the operation at all expected service conditions. Any omission in the requirements of complete brushless excitation system as well as the requirements in specifications shall not relieve the CONTRACTOR from his responsibility to supply a complete system. A complete description of the proposed system and equipment shall be provided in his bid.

The system shall be capable of providing a sufficient margin of stability under all steady and transient load conditions.

Brushless excitation systems shall be in accordance with IEC 60034.

To improve the stability of the network each Generating Unit shall be required to include Power System Stabilizing (PSS) and VAR limiting equipment as well. The PSS shall be of digital-Accelerating Power type and shall be in accordance with the requirements of the Saudi Grid Code.

It shall gain, together with the voltage regulator described below, a very sensitive and quick-acting control of the generator voltage and reactive power. The exciter response at rated load of the main excitation unit shall be according to IEC 60034.

It should maintain the generator terminal voltage within ±5 per cent of the rated voltage with all load conditions.

Manual excitation shall be provided with automatic tracking in case of failure of AVR when operating on AVR mode, in order to ensure bumpless automatic changeover to manual mode.

The excitation control system must be able to control either the generator terminal voltage or a remote bus voltage without instability over the entire operating range of the generating unit. Provision shall be made for proportional distribution of reactive power generation among the individual


Page 8 of 42

Power Units of the Plant. Control Performance of the Exciter/Automatic Voltage Regulator (AVR) system shall be such that under isolated operation conditions the damping coefficient shall be above 0.25 for the entire operating range.

The excitation control system shall have no negative impact on generator oscillation damping. In order to prevent voltage instability, the step-up transformer on-load tap-changer and the excitation control must be coordinated properly.

Limiters shall be provided for under excitation, over excitation and overfluxing. Each limiter shall have adjustable settings. Circuits shall be provided for reactive load sharing with other machines and line drop compensation. A power system stabilizer and a reactive power controller shall also be provided.

1.7 Generator main connections and neutral earthing

1.7.1 General The main connections between the generator and step-up transformer shall be made in

isolated-phase enclosed busbars.

The connections shall be capable of withstanding the maximum prospective short circuit fault currents and under exceptional conditions due to sudden disconnection of load on the generator shall be able to operate at a voltage of approximately 140 per cent normal voltage for a period not exceeding 1 min.

Generator neutral connections shall be capable of withstanding the maximum phase-to-earth fault.

The maximum allowable temperature under maximum continuous load operation shall not exceed:

• Conductor temperature 85°C

• Enclosure temperature 70°C

1.7.2 Design

The isolated-phase enclosed busbars shall comply with the requirements of BS 159, IEC 60071, IEC 60105, IEC 62271-1, and IEC 62271-200.

Evidence of relevant type tests shall be submitted with the Tender. The isolated phase busducts shall subjected to tests to determine the fault current carrying capability, temperature rise, conductivity, power frequency and routine tests. Details of these tests are included in schedule G.


Page 9 of 42

1.7.3 Conductors, flexible connections, joints and disconnecting links

Conductors shall be aluminium or copper in accordance with the requirements of the referenced standards. The external surface of conductors shall be painted matt black to improve heat dissipation.

Flexible connections to accommodate differential movement shall be provided where necessary. The flexible connections shall also ensure that no undue force or vibration is transmitted to conductors that are supported directly from the generator or transformers. Flexible connections shall be designed to act as removable isolation links.

The resistance of any length of conductor including a joint or flexible connection shall not exceed the resistance of an equal length of conductor.

Disconnecting links shall be arranged to facilitate earthing of the transformer side connections. The arrangement shall incorporate barriers to prevent access to the live connections subsequent to the disconnection of the transformer and the return to service of the generator.

1.7.4 Enclosures and insulators

Enclosures shall be aluminium in accordance with the referenced standards. The internal surface of enclosures shall be painted matt black to improve heat dissipation.

Enclosures shall be designed to exclude dust and moisture so that the installation is suitable for operation over long periods without the need for maintenance or cleaning of internal components.

Where enclosures are installed external to the building they shall be completely weatherproof and where necessary shall be painted to ensure protection against the effects of adverse environmental conditions.

Enclosures shall incorporate expansion joints, flexible joints and also inspection doors to facilitate the installation and maintenance of component parts of the busbar system. Rubber bellows shall be used to connect the enclosures to the generator, step-up transformer so as to insulate the connection between the enclosures and the particular plant or equipment.

Each phase enclosure shall be electrically continuous throughout its length and all three phases shall be bonded together each end including the tee-off connections.

At transformers the enclosure shall incorporate means to allow for thermal movement of the transformer and to accommodate for any small discrepancies in alignment or location.

The conductor shall be supported within the enclosure by an arrangement of porcelain or epoxy resin insulators. The arrangement shall allow for differential movement between the conductor and enclosure.


Page 10 of 42

1.7.5 Pressurization

The isolated-phase enclosed busbars shall be lightly pressurized with dry filtered air. The pressurization system shall include all air connections together with a unit local control panel. The control panel shall contain the filters, valves, safety valves and control devices associated with the system. The air supply for the pressurization system shall be taken either from the station instrument air system or a separate compressor and dryer provided. Whichever source is used 100 per cent redundancy of the air supply, drying and storage system shall be provided.

Drain plugs shall be provided at the lowest parts of the enclosures.

Remote and local alarms of high and low pressurization of the busbars shall be provided.

Facilities shall also be provided to blow out the busbars with dry filtered air and so facilitate rapid cleaning and drying of the installation following maintenance or a period of shutdown.

1.7.6 Earthing of main connections and connected plant and equipment

The enclosures of the isolated phase enclosed busbars shall be earthed at one point only and shall be otherwise insulated from earth along their length.

The enclosures of the isolated phase enclosed busbars and the metal frames of connected plant and equipment shall be connected to a dedicated earth bar. The earth bar installation shall be rated to carry the prospective maximum earth fault current from any part of the connections system, where an earth fault could occur, back to the generator. The earth bar shall be maintained at the potential of the main station earth.

Earthing switches shall be provided to connect each phase conductor to station ground for use during maintenance.

1.7.7 Supporting structures and wall seals Supporting structures for the busbar system shall incorporate means of allowing

differential movement and at the same time maintain electrical insulation of the enclosure from the structure and earth.

Where the busbar system passes through walls a suitable external sealing arrangement shall be provided between the enclosure and the wall. In addition a suitable internal sealing arrangement shall be provided between the conductor and enclosure when the busbar passes through an external fire wall. The external and internal seals shall have a minimum rating of 1 hour when the busbar system passes through fire barrier walls.

The busbar system shall not exert any forces on the walls.

1.7.8 Termination enclosures

Where it is not possible to terminate the isolated-phase enclosed busbars directly to the generator suitable phase-segregated type aluminium enclosures shall be provided. Enclosures shall


Page 11 of 42

be designed to incorporate adequate access facilities but at the same time preventing the ingress of dust and moisture.

The line side and neutral side enclosures for the generator shall accommodate the necessary quantity and type of current transformers. The secondary connections of the current transformers shall be provided in a terminal box mounted externally on the respective enclosure.

The generator neutral enclosure shall also accommodate the star point connection for the generator stator windings together with the generator neutral earthing equipment.

If hydrogen cooled generators are provided, hydrogen detectors shall be installed at the generator end of the line and neutral IPBs. An alarm shall be provided both locally and remotely to monitor hydrogen leakage into the busduct enclosures.

1.7.9 Voltage transformer cubicles

Floor mounted cubicles shall be provided to accommodate the necessary voltage transformers and associated primary winding fuses. The cubicles shall be of phase-isolated or phase-segregated type and provided with individual isolating facilities.

The isolating facilities shall apply earth connections to the supply side of the primary winding fuse and also the primary and secondary windings before access can be gained to the voltage transformer. The isolating facilities shall be interlocked with the cubicle door. Once access is gained to the voltage transformer it shall not be possible to make contact with any live parts and shutter arrangements shall be provided as necessary.

The enclosures shall be provided with anti-condensation heaters. The electrical supplies to the heaters and lighting shall be provided with suitable externally mounted isolation, indication and control equipment.

As a minimum three phase sets of voltage transformers shall be provided for each generator as follows:

i. One set for statistical main metering

ii. One set for relay protection channel A, automatic voltage regulator channel A and synchronizing

iii. One set for relay protection channel B, automatic voltage regulator channel B and instrumentation

1.7.10 Neutral earthing

The generator shall have a stator windings neutral earthing system comprising a low ohmic value resistor connected to the secondary of a single-phase power transformer with the primary winding of the transformer connected from the generator neutral point to earth. The neutral equipment shall be designed to limit the phase to ground fault current under 10 Amps.


Page 12 of 42

The single-phase power transformer shall be dry-type in accordance with the requirements of IEC 60076-11.

The low ohmic resistor shall be metal grid type in accordance with IEEE 32.

1.7.11 Generator switchgear

The generator switchgear shall be the SF6 type and designed to be compatible with the isolated-phase enclosed busbars and shall be rated in accordance with the requirements of IEC 62271-201 and IEEE C37.013.

The rated short-circuit current interrupting capability of the circuit breaker shall be achieved without the use of any intentional time delay device. The circuit breaker shall be capable of all switching duties, including but not limited to: load current, system source short-circuit currents, generator source short-circuit currents (including short-circuit currents with delayed current zeros), out of phase current, without creating overvoltages that could damage connected equipment. The switchgear equipment shall be rated without any requirement for forced cooling.

The switchgear shall include an isolating switch on the outgoing circuit side together with earthing switches on both sides of the unit. The switchgear shall be complete with surge arresters, protective capacitors, current and voltage transformers (on both sides of the circuit breaker), . All of these component parts shall be included in the common enclosure of the switchgear.

Type tests to establish switchgear and circuit breaker ratings shall be carried out in accordance with IEC 62271-100 and IEEE C37.013. Full copies of the type test certificates shall be provided together with calculations detailing the required symmetrical and asymmetrical interrupting ratings for the circuit breaker in the particular application. The approval of the proposed equipment shall be dependent upon satisfactory review of submitted type test certificates and calculations of the required interrupting ratings for the proposed application.

The ratings of the isolating and earthing switches shall be compatible with those for the isolated phase enclosed busbars.

The isolating and earthing switches shall be motor driven. Facilities for emergency manual operation of the outgoing isolating switch shall also be provided together with key operated interlocking in the closed and open positions and an interlock to prevent motor operation when the isolating switch is under manual operation.

The circuit breaker shall also be provided with facilities for emergency manual operation.

Mechanically driven semaphore position indicators shall be provided in readily visible positions for the circuit breaker and all isolating and earthing switches. Windows shall also be provided in appropriate parts of the switchgear enclosure to allow visual checking of the position of the isolating and earthing switches.


Page 13 of 42

The enclosures of the switchgear shall be welded to the adjoining enclosures of the isolated phase enclosed busbars to ensure continuity of the enclosure characteristics.

The switchgear shall be suitably arranged and provided with lifting facilities to allow maintenance work to be carried out easily.

The switchgear shall be provided with a cabinet housing all control and supervisory equipment. Local control shall be provided for the circuit breaker and all switches. Local/remote control selection facilities shall also be provided. The switchgear control and supervisory system and monitoring system shall be designed to facilitate integration into the overall power station control system. The switchgear system shall incorporate the interlocking scheme and disturbance recorder and a local display screen shall display operational supervisory information. The cabinet shall provide space for the accommodation of generator synchronizing equipment and generator protection equipment as necessary.

1.7.12 Sulphur hexafluoride (SF6)

Where sulphur hexafluoride is used for switchgear or EHV cable terminations it shall be technical grade industrial pure gas for use in electrical equipment in accordance with the requirements of IEC 60376.

Equipment containing sulphur hexafluoride shall be subject to the requirements for safe handling in accordance with IEC TR 61634 and IEC 60480.

A pressure gauge and gas density monitoring system shall be provided on all equipment containing sulphur hexafluoride.

1.8 Transformers

1.8.1 General All three phase transformers shall be of core type construction. Transformers for indoor

installation shall be dry type. All transformers shall be complete with all accessories and necessary auxiliary equipment. All transformers shall comply and be rated in accordance with applicable SEC standards and IEC 60076.

The terminal arrangement and connections shall not restrict access for maintenance and inspection. All windings below 72.5 kV shall be fully insulated.

The LV terminals of the generator transformer shall be arranged for connection of isolated phase busbars. The EHV terminals of the generator transformer shall be arranged for connection of 380kV EHV XLPE cable. 380kV EHV XLPE cable will be routed up to 380kV GIS substation.

The transformers shall be designed with particular attention to the suppression of harmonic currents, especially third or fifth so as to minimize interference with communication circuits.


Page 14 of 42

Cable boxes shall be suitable for the connection of XLPE insulated cables. The body of the cable box shall be provided with an earthing bolt or stud. Cable boxes shall be air insulated. Phase segregated cable boxes shall be used for single core cables. LV terminals of auxiliary transformers shall be fully insulated.

Cable sealing end chambers shall be oil filled and of an approved design suitable for accommodating the 380kV EHV XLPE cables. The chambers shall have flanged joints and gaskets, and shall be provided with removable covers. The faces of the flanges shall be machined or ground.

The chambers shall be designed to accommodate the cable sealing ends required to terminate the cables, including stress cones or other approved means for grading the voltage stress on the terminal insulation of the cables.

The sealing end chambers shall be suitable for operating outdoors under all loading conditions up to the rated load of the transformer, and any cyclic overloading conditions which may be specified. Insulating oil used for filling the sealing end chambers shall conform to the requirements of IEC 60296.

A drain valve shall be provided at the lowest point of the chamber, in addition to a filter valve fitted at the top of the chamber.

Facilities for testing shall be provided in the cable sealing end chamber. The sealing end chambers shall be isolated phase type.

Sealing end chambers shall be tested in the same manner as the transformer tank.

1.8.2 Station auxiliary transformers Dry type transformers shall have Class 155 (F) insulation, but the relevant temperature

rises and total temperatures shall not exceed the limits for Class 130 (B) under all site and operational conditions, and an enclosure to IP31.

Dry type transformers shall be complete with off circuit tapping links. The tapping links shall be accessible without the complete removal of the transformer enclosure.

1.8.3 Oil filled transformers Generator transformers shall be rated to match the generator continuous maximum output

over the full range of taps and system voltage taking the future installation of TIAC into account under all site ambient conditions with a maximum power factor of 0.8. (see Schedule AA).

Generator transformers shall be designed, manufactured and tested as per the Generator Unit Transformer Specification SEC-GP-001-R02 (2009). The generator transformer shall be capable to withstand high over current produced by out of synchronism connection of the generator to the system in accordance with IEC 60076-5 recommendations.


Page 15 of 42

Generator transformer HV bushing shall be suitable for connecting to 380kV cable. HV bushing should have two set of CTs for 380kV cable differential protection purpose.

Generator transformers shall have ONAN/ONAF cooling with a complete standby forced cooling set of facilities. The cooling fans shall be automatically controlled. The maximum hot spot temperature of the transformers under all site and operational conditions shall be 98°C. The cooling system shall be provided with failure alarms.

Oil filled transformers shall be fitted with lockable drain valves to enable all oil filled compartments to be drained, and adapters shall be provided for connection to oil filtration plant. Sampling devices shall also be fitted independently of the drain valves. It shall not be possible for:

a. the oil in the diverter switch compartment to mix with oil in any other compartment,

b. The oil in the sealing end chambers to mix with that of the main tank.

First filling of oil shall be provided for each oil filled transformer. The grade of oil shall comply with the requirements of IEC 60296.

Silica gel breathers shall not use cobalt chloride.

Pressure relief devices shall be provided on each oil filled compartment. These devices shall discharge oil at ground level. Facilities shall be provided for these alarms to be repeated to the DCS supplied by SCGT Contractor.

Safe access shall be provided to generator transformer conservators and Buchholz relay. This shall take the form of an access ladder with hoops.

Radiators which are connected directly to the tank shall be detachable. Radiators which are mounted separately shall be mounted on a concrete base.

Tap position indicators for on load tap changers shall be provided both locally and for connection to the DCS. On load tap changers shall be installed on the HV winding and comply with IEC 60214.

All oil filled transformers shall be fitted with oil and HV/LV winding temperature indicator that can be manually reset. Indicators shall have an analogue output of 4 ~ 20 mA for connection to the DCS. Alarm and trip facilities shall also be provided.

Marshalling kiosks for oil filled transformers shall be complete with temperature indicators, test facilities, interposing relays for supervisory control, control and protection for cooling plant with an auto-manual changeover switch. Each generator transformer kiosk shall include a single phase and a three phase socket.


Page 16 of 42

Bushings that house current transformers shall be arranged so that they can be removed without disturbing the current transformers, secondary terminals, connections or pipework.

The construction and mounting of all bushings shall ensure that, in the event of flashover, current has a definite path around joints fitted with gaskets. On capacitor type bushings a tapping shall be brought out to a separate terminal for power factor testing at site. The terminal shall be earthed when the weatherproof cover is in position. Stress shields shall be regarded as part of the bushing assembly.

Internal connections to transformer bushings shall be flexible.

On line condition monitoring equipment shall be fitted to transformers with ratings greater than

20 MVA. The system shall comprise sensors to monitor the following:

• Dissolved gas production in oil.

• Water content in oil.

• Partial discharge (generator transformer only).

• On load tap changer.

The system shall be complete with indicating and data logging equipment.

MV/LV station auxiliary transformers shall be provided by CCGT Contractor as required for the balance of plant electrical systems for steam turbine generating units, HRSGs, ACC system and Water Treatment plant.

1.9 Switchgear

1.9.1 General All ancillary equipment within the switchgear shall comply with IEC 60947.

The height of any extensions to existing switchgear is to be the same as the existing equipment. The operating handles of switchgear extensions shall also be within the same height envelope as the existing.

All switchgear shall be accessible for maintenance without the need for extensive removal of internal equipment.

Motor starters for motors which are rated at 100 kW and above, and variable speed drives shall be equipped with an intelligent microprocessor measurement unit. This unit shall be capable of communicating with the DCS.

All MV and important LV motor starters shall be complete with a start-up counter.


Page 17 of 42

Extensions to any existing switchgear shall be controlled from the same point as the existing equipment. Any new switchgear supplied for the steam turbine shall be controlled by the steam turbine control system.

Under emergency supply conditions the existing LV switchgear is controlled by the DCS, , this is to achieve suitable and safe electrical system configurations and the provision of emergency power requirements to the open cycle power station under mains failure conditions by SCGT Contractor.

The emergency power requirements of the steam turbine generating units, HRSGs, ACC system and Water Treatment plant shall be integrated with the existing scheme, including liaison with SCGT Contractor/Company/Engineer as appropriate, for the rating of the diesel generators and associated LV switchgear.

Motor starters for MV motors and variable speed drive circuits shall be equipped with a motor protection relay with contacts for remote indication.

Any new switchgear and extensions to existing switchgear shall be provided with the same control, indication and alarm facilities as the existing equipment.

Indoor equipment shall have a degree of protection to IP41, outdoor equipment shall be IP65 and located under a canopy to protect from both sun damage and damage caused by sand storms..

It shall not be possible to accidentally access live parts of the equipment.

Control sections and cable compartments shall be provided with internal lighting.

The control voltage supply to both new and extensions to existing LV switchgear/MCCs shall be the same as that for the existing equipment.

Internal wiring shall be run in LSF trucking and be colour coded to ANSI Standards. No more than two wires shall be connected to one terminal. Wires shall be identified at each end. Wiring above 50 V, or wiring connected to pilot cables shall be segregated from other wiring. Control wiring shall consist of stranded copper conductor not less than 1.5 mm2. Wire insulation shall be 750 V class, thermosetting and moisture, heat, oil and flame retardant.

Terminal blocks shall be moulded composition type with separate terminals for internal and external connections and shall be provided for all secondary and control wiring requiring external connections. A minimum of 20 per cent spare terminals shall be provided on each terminal block. All terminal blocks shall be labelled with a unique identification reference..

All indicating instruments shall be in accordance with IEC 60051 Class 1.0. Motor ammeters shall be capable of withstanding motor starting currents. Voltage operated instruments shall be protected by a fuse.


Page 18 of 42

Each switchboard shall be complete with an earth bar along the length of the switchboard. All framework, metal enclosures, barriers, and non-current carrying parts of equipment shall be securely earthed to the earth bar which shall be connected to the earthing system.

1.9.2 MV switchgear

The existing MV switchgear (13.8 kV and 4.16 kV) shall be extended, in accordance with drawing No 162749/PBP/0003 using equipment and that complies with IEC 62271-100 and IEC 62271-200. The CCGT Contractor shall provide similar equipment as that supplied by SCGT Contractor.

The existing switchgear designed to meet combined cycle power flow requirements. However CCGT contractor shall supply extension of feeders as well as new switchgear as per CCGT requirement.

CCGT Contractor shall co-ordinate all supplies, work and construction interface activities with the Engineer and the Company (SEC) as necessary for successful completion of all existing MV switchgear for their extensions and its interface activities. The work to be done relates to MV switchgear extension and interface with existing SCGT Contractor MV switchgear. The MV switchgear shall normally be controlled from the DCS. Circuit breakers shall be fully withdrawable for maintenance and isolation purposes. VTs shall be supplied through fuses on the primary side. It shall be possible to remove the fuses without dismantling the equipment. Each compartment shall be pad lockable.

Cable and busbar earthing facilities shall be provided. Busbar earthing shall be electrically interlocked.

The short time rating shall be in accordance with the results of the fault studies.

Busbar and circuit shutters shall be individually operated and able to be independently padlocked closed.

All auxiliary switches shall be wired to a fixed terminal board.

Suitable handling equipment shall be provided for circuit breakers where new equipment is provided. Handling equipment is not required for switchgear that is an extension to existing equipment.

Mechanical or electrical safety interlocks shall be provided for isolation and maintenance and to avoid unsafe switching conditions.

A steel cabinet shall be provided for tools and maintenance equipment, and a separate cabinet shall be supplied for keys and padlocks, which shall be compatible with those supplied by SCGT Contractor. Each room in which MV switchgear is installed shall be provided with an insulated hook.


Page 19 of 42

MV Switchgears shall be provided with all required protective relays. The existing protection scheme and interlock system shall be extended/modified.

1.9.3 LV switchgear

LV switchgear includes Power Control Center (PCC), Power & Motor Control Center (PMCC) and Motor Control Center (MCC).

LV switchgear shall be freestanding, with segregation to Form 4b in compliance with IEC 60439-1.

Current ratings for standardized products shall be designed for 50°C ambient temperature. If upon the increased ambient temperature derating of the standard current rating becomes necessary, such derating shall be restricted to such an amount that a margin of 10 per cent is still maintained ahead of the actual circuit requirement.

CCGT Contractor shall co-ordinate all supplies, work and construction interface activities with the Engineer and the Company (SEC) as necessary for successful completion of all existing LV switchgear interface activities.

A minimum clearance of 1 metre shall be provided to the rear and at the ends of each LV switchboard.

The LV switchgear shall normally be controlled from the DCS.

Voltage monitoring and measuring equipment shall be provided for incomers and busbars. Each section of board shall be complete with definite time delayed, two-phase undervoltage relay (27), adjustable in steps.

Circuit breakers shall be air break and horizontally withdrawable. All motor starters and feeder cubicles shall be fully withdrawable.

The short time rating shall be in accordance with the results of fault studies.

Contactors shall be capable of withstanding the motor stalled current until the associated protection device operates. Contactors shall comply with IEC 60439-4, including Type ‘2’ co-ordination.

Busbars shall be copper, and shall comply with IEC 60439-2. Busbar insulation shall be in accordance with the relevant phase colour.

All auxiliary switches shall be wired to a fixed terminal board.

Composite fuse and switch equipment in the form of either a fuse-switch or switch-fuse shall comply with IEC 60439-3.


Page 20 of 42

Each switchgear/switchboard section and MCC shall be provided with at least 10 per cent or a minimum of one of the following:

• empty compartment of each type as a spare complete with all internal wiring, terminal blocks, contactors, and relays,

• fully equipped and functional spare outgoing feeder of each type.

The switchgear shall also be provided with:

• 125V DC control voltage

• Two incomers and a bus section operating on a two from three basis

Suitable handling equipment shall be provided for new circuit breakers or starters for each switchgear room.Handling equipment is not required for switchgear that is an extension to existing equipment.

Mechanical or electrical safety interlocks shall be provided for isolation and maintenance and to avoid unsafe switching conditions. Padlocking facilities shall be provided in the breaker-operating handle to positively lock the breaker in the off position with the door open or closed. A mechanical position indicator shall be provided to indicate the ON, tripped and OFF positions of the breaker.

LV Switchgear shall be provided with all required protective relays.

1.10 Current transformers

All current transformers shall comply with IEC 60044-1. Current transformer secondary windings shall be earthed at one point only through an accessible link. The secondary windings shall have a 1 A or 5 A rating as appropriate. Facilities shall be provided to allow primary injection testing with minimum disturbance to the equipment. CT burden requirement calculations that ensure enough margin on the CT shall be submitted for the Engineer and Company (SEC) approval.

The following accuracies shall be used:

a. Tariff metering Class 0.2S

b. Instruments Class 0.2 ISF ≤5

c. Differential protection Class PX

d. Other protection Class 5P


Page 21 of 42

1.11 Voltage transformers All voltage transformers shall comply with IEC 60044-2. For MV applications the primary

windings shall be connected through renewable fuses. The secondary winding of all VTs shall be provided with an accessible phase coded fuse or miniature circuit breaker. VT secondary circuits shall be complete and earthed at one point only. It shall not be possible to connect VT secondary circuits in parallel where the VTs are connected to different sections of busbar.

VT fuse failure detection, alarm and interlock shall be provided.

The following accuracies shall be used:

a. Tariff metering Class 0.2S

b. Instruments Class 0.2

c. Protection Class 0.2/3P

1.12 125V DC supply system There shall be one (1) dc system for each steam turbine generating unit and one for the

balance of plant at each location. Each system shall have two independent fully rated batteries and associated 100 per cent per cent rated battery charger and dc distribution board. A float/boost charge/equalising selector switch shall be provided for each charger. The batteries shall normally be of the sealed Nickel cadmium type and connected to the load, and will supply the loads when ac supplies to the chargers are lost.

Each Ni-Cd battery shall be capable of supplying its associated connected load for a period of 6 hours.

Each battery shall be complete with stands, all intercell connections, and connections between the battery terminals and the switchgear. The stands shall be two level and designed to alleviate the requirement for a cell lifting device.

Indicating lamps shall be provided on the equipment to indicate battery faults, the faults shall also be remotely indicated to the DCS.

Battery chargers shall have natural cooling. It shall be possible to carry out maintenance on one charger with the other in service. Each charger shall be capable of recharging the battery within eight hours after a complete discharge.

The batteries, battery rooms, and ventilation system shall be designed in compliance with BS 6133.


Page 22 of 42

1.13 UPS system A UPS system has been provided for the DCS and control /protection systems for the

SCGT power plant. CCGT Contractor shall provide additional UPS facilities to cater for equipment in his supply. Suitable uninterruptible power supplies (UPS), with 100 per cent redundancy, shall be provided with the following facilities. The UPS shall be provided to support the DCS and other control/protection systems in the event of a power failure. The system shall be designed to provide electrical noise free power for a minimum of 6 hours continuously in the event of a blackout and minimum life time of 50000 hours or better is required for the complete system including the batteries, chargers and inverters and contactors.

In general, each UPS shall consist of the following components:

i. 3-phase rectifier/battery charger unit.

ii. 1 or 3-phase static inverter.

iii. 1 or 3-phase static by-pass isolators.

iv. Sealed Ni-Cd batteries.

The UPS shall automatically support the total load presented by the DCS and other control/protection and safety systems equipment on mains failure without a break in supply. Alarms shall be displayed on the alarm fascia in the event of a mains failure or of a fault in the UPS as well as on the DCS. Reinstatement of normal supplies shall be effected automatically without the need for re-programming or operator intervention. Each UPS shall be supplied with a comprehensive battery monitor which shall alert the operator to any problems. No single failure in the UPS or the equipment it supplies shall cause a plant shutdown.

For maintenance purposes an independent manual by-pass switch shall be provided to allow the DCS to be powered from an alternative source. This shall allow maintenance procedures to be carried out safely and without interruption to the system operation.

Where hydrogen is generated the correct precautions of a hazardous zone shall be taken.

The UPS shall comply with IEC 62040-3 and be rated at 125 per cent of full load. The stand-alone time at 150 per cent of rated output for 1 minute followed by 125 per cent of rated output for 10 minutes, shall not be less than 6 hours at 100 per cent of rated load.

The UPS shall be suitable for operation with an input voltage variation of ±10 per cent and a frequency variation of ±5 per cent.

The equipment shall be mounted in a cubicle with a degree of protection to IP41.


Page 23 of 42

1.14 Protection

1.14.1 General There shall be two sets of main protection such that the loss of one set or failure of one

set to clear a fault will not result in time delayed tripping of switchgear. Each set shall be fed from different current transformers.

High speed discriminative protection systems shall be engineered as complete schemes, with due account being taken of current and voltage transformer performance.

All relays performing a measuring function shall be of numerical design with continuous self-monitoring.

Numerical relays and schemes provided shall all be suitable for connection to a local communications network, and provided with an integral local user interface.

DC supply supervision relay, lock-out relay, lock-out relay coil supervision relay, CB trip coil supervision relay, auxiliary relays and devices etc., shall be provided to complete the required protection system.

Protection relays shall be type tested in accordance with the relevant sections of IEC 60255. Each protection relay shall have means by which the user can apply the settings, and a unique identifier which is clearly visible.

All back up protection systems shall be able to discriminate with main protection systems, circuit breaker fail protection and other back up protection systems installed elsewhere on the system.

Adequate facilities shall be provided within the protection scheme to enable the protection equipment to be tested from the front of the protection equipment panel with the primary circuit(s) in service with test points clearly labelled.

The protection system shall operate satisfactorily when tested to IEC 60068-2, IEC 60255-21, and IEC 60255-22.

CCGT Contactor shall integrate the protection of the steam turbine driven generators, HRSGs and balance of plant into the existing overall power plant protective relay system to form a combined cycle power station and submit associate relay setting calculations.

1.14.2 Generator protection As a minimum, the generator protection shall comprise two multi-function relays with the

following functions:

a Differential

b Generator overload


Page 24 of 42

c Stator earth fault (100 per cent)

d Stator earth fault (90 per cent)

e Rotor earth fault (Two stage, alarm and trip)

f Under frequency

g Over frequency

h Over fluxing

i Overvoltage

j Under voltage

k Over current

l Loss of excitation

m Over excitation

n Reverse power

o Impedance relay

p Negative phase sequence

q Pole slipping

r Dead machine energization

s Generator VT fuses failure.

1.14.3 Generator excitation system As a minimum, the generator protection shall comprise two multi-function relays with the following functions: Rotor earth fault

1.14.4 Generator transformer protection As a minimum, the generator transformer protection shall comprise the following

functions:

a Overall differential

b Differential


Page 25 of 42

c Restricted earth fault

d Overcurrent and earth fault

e Standby earth fault

f Over fluxing volts/Hz (Two stage alarm and trip)

As a minimum, the following supplementary generator transformer main tank protection devices shall have also been provided:

a Buchholz

b Over temperature (oil and winding, two stage)

c Overpressure

d Oil level.

Generator transformers with cable sealing end chambers on the EHV side shall be provided with a Buchholz for each chamber.

A Buchholz shall be provided for on load tap changers.

1.14.5 380kV cable protection a Differential protection (Main 1)

b Differential protection (Main 2)

The digital differential protection (Main 1) shall be phase-segregated in operation and it shall offer uniform sensitivity for all types of fault at all locations within the protected circuit. A pair of optical fibres shall be utilized for end-to-end data transfer. Voltage and current waveform disturbance recording and event-logging shall be included as part of this protection system.

Main 2 shall be as for Main 1, but of different design and manufacture and without integral disturbance recording.

1.14.6 Dry type transformer protection Dry type transformers shall be provided with the following protection functions as a

minimum:

a Overcurrent and earth fault (50/51, 50N/51N)

b LV standby earth fault (51G)

c LV over current and earth fault (50/51, 50N/51N).


Page 26 of 42

All dry type transformers shall be provided with winding temperature protection (49).

1.14.7 MV Motor Protection a Differential (for motors >1MW)

b Thermal replica

c Negative phase sequence

d Overcurrent/earth fault

e Locked rotor

f Undervoltage

1.14.8 LV Motor Protection a Single phasing (up to 90kW where fuses are used)

b Thermal replica

c Locked rotor

d Overcurrent (for motors > 30kW)

e Negative phase sequence

f Earth fault (for > 90kW)

g Unbalance (for > 90kW)

1.15 Synchronizing

Each generating set shall be arranged to have an auto-synchronizing scheme, synchronizing each of the generators across the respective generator circuit breaker.

Two steam turbines will be connected to each EHV breaker via isolators, therefore EHV circuit breaker synchronisation is not envisaged.

Each scheme shall be provided with a check synchronizing relay and selector switch for manual, auto, and test and off. The test position shall be a simulation of the circuit breaker closing. Manual synchronizing shall be provided.

1.16 Metering

The tariff metering system shall include main and check meters. All meters shall be suitable for three phase imbalanced loads, be Class 0.2S, and shall comply with IEC 60687. The output from the tariff meters supplied for the CCGT shall be accessible from the DCS. . The metering


Page 27 of 42

system shall measure net export of total active and reactive power from each generator at the 380kV substation.

1.17 Motors

Motors shall comply with the requirements of IEC 60034 and IEC 60072. All motors rated 100 kW and above shall be fitted with winding temperature detectors. Motors rated 150 kW and above shall be medium voltage. Motor ratings shall be 5 per cent above than the mechanical requirement of the driven equipment.

Motor enclosures shall be IP54 for indoor applications and IP55 for outdoor applications, and shall be totally enclosed fan cooled.

Motors located outdoors shall be provided with a canopy covering the terminal box.

Winding insulation shall be to Class 155 (F) with temperature rises and total temperatures restricted to Class 130 (B) limits.

All MV and LV motors rated above 30 kW shall be fitted with anti-condensation heaters.

Rolling element type bearings shall comply with ISO standards. Oil lubricated bearings shall be fitted with an accessible drain plug, and means of observing the oil flow.

Where applicable, the thrust bearing on vertical type motors shall be co-ordinated with that of the pump.

Terminal boxes shall be totally enclosed to prevent the ingress of dust and moisture. The supply cable shall have a separate terminal box. LV motors shall have insulating barriers between terminals; MV motors shall have phase segregated terminals and vibration monitoring equipment.

Materials for air coolers shall be selected to provide resistance to corrosion.

1.18 Variable speed drives Variable speed drives shall be used wherever possible to optimize energy efficiency and

control performance.

All variable speed drives shall be of the variable frequency adjustable speed type and comply with the requirements of this subsection.

The drive shall be a variable frequency solid state 12 pulse width modulated (PWM) adjustable speed converter applied to a cage induction motor. The motor shall be suitably derated to allow for voltage and current harmonics developed by the converter. The motor shall be rated for continuous operation at any point throughout the speed and duty range.


Page 28 of 42

The converter unit shall be self-contained in a sheet metal enclosure with IP 31 degree of protection, with inlet and outlet filters where necessary, and shall be located indoors. The cubicle and equipment therein shall comply with the appropriate clauses of this Specification.

The converter unit shall be suitable for direct connection to the ac mains supply and shall have a regulation accuracy of ±1.0 per cent under all conditions. There shall be provision to ramp up and down to suit plant requirements.

The converter equipment shall generally comply with IEC 60146 where appropriate. Calculated levels for individual harmonics and THD shall be submitted. These calculations shall include individual drives and also the maximum number of drives connected to main power switchboards.

The converter shall be complete with all necessary control and operating circuits, instruments, alarms, isolators, contactors and circuit breakers for remote automatic and manual control, local to the motor control, and testing at the converter cubicle of the complete drive.

1.19 Earthing A site survey shall be undertaken, to determine the soil resistivity in the steam turbine

generator unit, HRSGs, ACC system and Water Treatment plant areas. Based on the results, a study shall be carried out to determine the touch and step potentials of the new plant areas

The design and installation of the earthing system for the new plant areas shall comply with IEEE 80, IEEE 665, IEEE 1050 and BS 6739.

All sub-grade earthing conductors shall be bare tinned stranded high conductivity copper to IEC 60228. Subgrade connections shall be made using the exothermic welding process. The area around the conductor shall normally be backfilled with the excavated soil. Should this soil be of an aggressive nature, a suitable backfill material shall be used.

The earthing grid(s) shall be interconnected with the earthing grid installed by SCGT Contractor at least, two points.

Main earthing grid conductor shall be of minimum 240 mm2.

Bolted or clamp connections shall only be used above ground.

For above-ground insulated grounding conductors shall be used.

All joints within the earthing system shall have a resistance not exceeding that of an equivalent length of conductor.

Earthing distribution bars shall be connected to the main earthing grid, be strategically positioned around the plant in accessible areas, and shall be supported from insulators. These distribution bars shall be of annealed high conductivity copper and pre-drilled.


Page 29 of 42

Where ground rods are used they shall be hard drawn high conductivity copper with hardened steel driving caps and tips to EN 13601. Inspection pits shall be of the lightweight type, UV stabilized and chemically resistant with a lockable lid. Test points with disconnect links shall also be supplied in inspection pits.

The base of each structural column and the steel reinforcing in each column foundation shall be bonded to the main subgrade earthing system. The connections on the structural steelwork shall be made clear of ground level.

The frame of all main items of electrical equipment shall be connected to the main earthing system at opposite ends of the frame. The conductors used shall have the same cross-sectional area as that of the main subgrade conductor, and shall be detachable from the earthing bolt or stud on the frame.

Storage tanks up to a diameter of 5 m shall have a minimum of two earth connections. Tanks between 5 m and 15 m in diameter shall have a minimum of three connections, those larger than 15 m in diameter shall have four connections.

One terminal of the single phase power transformer associated with the neutral earthing equipment for each ST generator shall be solidly earthed. Star connected HV windings of generator transformers shall be solidly earthed.

The substation earthing system shall be extended if applicable.

Isolated phase busbars shall be earthed in accordance with IEEE 665.

The casing of all other busbars may be used as the earth conductor where it can be proven that the enclosure and joints have the capacity to carry the prospective fault current. In this instance the casing shall be connected to the earth terminal of each item of electrical equipment to which the busbar is connected. Where it cannot be proven that the casing and joints have the capacity to carry the prospective fault current, an earth conductor shall be run alongside the enclosure and connected to the appropriate terminals on the electrical equipment. The supports for the busbars shall be connected to earth using the structural steel or earth distribution bars as appropriate.

Switchboard earth bars shall run the length of the switchboard and be connected to the main earthing grid at each end.

The method employed for earthing motors shall be dependent upon rating:

v. Up to and including 4 kW, earthed through the earth conductor of the supply cable.

vi. Above 4 kW up to 30 kW, through the earth conductor of the supply cable.

vii. Above 30 KW by a separate earthing conductor of not less than 70 mm2.


Page 30 of 42

viii. All MV motors connected using an earthing conductor not less than 70 mm2. For

MV motors supplied by three core cable, the cross-sectional area of connection to the cable armour from the motor earth terminal shall be not less than half that of the supply cable.

Crane tracks shall be earthed at both ends to an earthing distribution bar. In addition a separate earth wire and travelling brush shall be provided along the track.

Where multiple cable trays or ladder racks are vertically displaced along the same route, vertical earthing conductors shall link each tray or rack, and shall then be connected to the main earth at regular intervals.

Current transformers and voltage transformer secondary circuits shall be earthed at one point only through links situated in an accessible position.

Dedicated earth bars and disconnecting links for electronic equipment shall be clearly identified. Drain wires, cable screens and earth bars of instrument panels shall be connected to these dedicated earth bars. The electronic equipment earthing system shall be connected to the main earthing system at one point only.

Any PVC covered conductor used to connect equipment or structures to the main subgrade system or used underground in the vicinity of pipes shall not be considered as forming part of the earthing grid resistance.

All clamps, connectors, bolts, washers, nuts and other hardware used with grounding system shall be copper.

The method employed for aluminium to aluminium joints shall be dependent on the type of conductor. Strip conductors shall be MIG or TIG welded, joints for circular and rectangular conductors may use bolted clamps. The surface of the aluminium shall be thoroughly cleaned using a wire brush and a suitable compound applied. For bolted joints a torque spanner shall be used.

Aluminium to copper joints shall be bolted, cold pressure welded or friction welded. The surface of the aluminium shall be thoroughly cleaned using a wire brush and a suitable compound applied, the surface of the copper shall be tinned. The completed joint shall be protected by a compound or suitable sleeve.

Copper to copper joints may be jointed using any of the following procedures:

Bolting

Exothermic welding.

In corrosive atmospheres, the joint shall be protected.


Page 31 of 42

1.20 Lightning and surge protection

A complete lightning and surge protection system comprising a roof type network and down conductors shall be installed to protect the additional buildings, in addition to the existing system installed by SCGT Contractor, to form a complete system for the combined cycle power station, ACC and Water Treatment plant in accordance with the requirements of IEC 62305. The surge element of the protection should protect the network generally, including all connected/associated data services.

CCGT Contractor shall carry out a lightning survey.

The combined resistance to earth of each lightning protection system shall not exceed 0.5 ohms.

On completion of the installation or of any modification to it, the resistance to earth of each earth termination or section thereof shall be measured and the continuity of all conductors and the efficiency of all bonds verified to confirm conformity with design data.

Connections to electrodes and test links and clamps shall be housed in reinforced concrete pits with covers, which shall be adequately drained and labelled.

The complete installation shall be tested in accordance with IEC 62305 and copies of the test certification provided.

1.21 Cable & Cable Installation

1.21.1 General The cable installation shall be complete with all terminations, trays, ladder racks, glands,

ferrules, lugs, markers, and fixings.

Cables shall be in one continuous length, have high conductivity copper conductors, and comply with IEC 60228, IEC 60332-3-22. Cable through joints for cables other than EHV cables will not be accepted. Through joints for EHV cables will only be accepted where it can be proven that the maximum drum length is not sufficient to cover the cable route.

The maximum allowable temperature for XLPE cables under continuous operation shall be 90oC, with a maximum of 250oC under short circuit conditions.

Medium and low voltage power cables shall comply with IEC 60502 and IEC 60811.

High voltage power cables shall comply with IEC 60183, IEC 60840 and IEC62067.

The voltage drop between the point of supply and the fixed equipment shall be limited to 4 per cent.

The minimum voltage rating of all cables shall be 600/1000V.


Page 32 of 42

All power cables shall have phase identification.

Single core power cables shall be earthed at one end only.

PVC sheathing shall comply with IEC 60811 and IEC 60885 and have an oxygen index of not less than 30.

Building services wiring shall have XLPE insulation.

All cables shall be flame retardant.

1.21.2 EHV cables All EHV 380kV cables shall be XLPE insulated. The cable shall comply with IEC 60183,

IEC 62067.

1.21.3 Medium voltage cables All medium voltage (13.8 kV and 4.16 kV) cables shall be XLPE insulated, armoured with

an LSF sheath.

1.21.4 Low voltage cables All low voltage cables shall be XLPE insulated, armoured with a LSF sheath.

1.21.5 Continuous and fault current carrying capacity CCGT Contractor shall submit design calculations to demonstrate that:

a The maximum continuous current carrying capacity of any power cable will not be exceeded after taking installation dependent derating factors into account.

b The mechanical bursting capacity of any multicore power cable will not be exceeded under short circuit fault conditions.

c The maximum short circuit rated conductor temperature will not be exceeded under fault conditions; the initial conductor temperature shall be taken as equal to the maximum continuously rated temperature of the insulation for the purposes of these calculations.

d The maximum short circuit rated armour temperature will not be exceeded under fault conditions; the initial armour temperature shall be taken as equal to the maximum continuously rated armour temperature for the purposes of these calculations.

All calculations shall take into account abnormal running arrangements resulting from the outage of any one switchboard, transformer or circuit.

The conductor cross-section of each cable shall be adequate for carrying the prospective fault current determined by the next upstream short circuit protection device.


Page 33 of 42

Short circuit fault calculations shall take full account of both the ac and dc components of the fault current.

1.21.6 Instrumentation and control cables All multicore control cables shall have approximately 20 per cent spare cores, but not less

than two cores for future use. All cores shall be PVC or XLPE insulated, armoured and numbered throughout their length. Overall and individually screened twisted pairs shall be used for all analogue signals and overall screened multicore cables shall be provided for all other applications.

1.21.7 Optical fibre cables The fibre optic cables (FOC) shall comply with IEC 60794 and shall be designed for indoor

or outdoor (according to requirement) environments including inside buildings in riser shafts, metal conduits/raceways above the ceiling and duct banks between buildings. High Density Polyethylene (HDPE) sub-ducts shall be used to protect cables in the underground duct bank.

The cable jacket shall be flame retardant OFNR riser-rated, as per NFPA, and water resistant with colour coding to help distinguish fibre media from other premises cable. The cable shall be totally non-metallic in construction.

The cables shall be multi-mode, tight-buffer and graded index type. The maximum attenuation shall be 1 dB/km at 1300 nm wavelength.

Low-loss single-mode FOCs shall be used for long distance trunk links.

1.21.8 Telephone cables All telephone cables shall have a minimum of two pairs of tinned solid conductors. The

minimum conductor diameter shall be 0.5 mm. All telephone cables shall have colour coded core insulation.

The insulation and outer sheath of telephone cables for internal use shall be halogen free. Cables with more than six pairs shall have a fire barrier tape.

All telephone cables for external use shall have cores embedded in water repellent gel to prevent the ingress of moisture and an outer sheath of tough UV resistant polyethylene.

1.21.9 High temperature cables

Silicon insulated cables shall be used for applications such as alarms, lighting, and essential services in temperatures between –60°C up to 180°C. Stranded conductors shall be to IEC 60228/VDE 0295 Class 5. A glass fibre braid shall be applied over the silicon insulation, with a silicon outer sheath. A glass fibre tape shall be applied over the silicon sheath with an outer galvanized steel wire braid.


Page 34 of 42

1.21.10 Thermocouple and compensating cables Only one colour shall be used for the insulation of the negative conductor of both

thermocouple extension and thermocouple compensating cables. The insulation of the positive conductor and the outer sheath shall be dependent on the cable type.

1.21.11 Intrinsically safe cables Cables used for intrinsically safe circuits shall have a blue outer sheath in accordance with

IEC 60079-14. No other cables shall be supplied with a blue outer sheath.

1.21.12 Mineral insulated cables Mineral insulated (MI) cables shall have copper conductors surrounded by a compressed

non hygroscopic mineral insulate with a copper sheath and a halogen free LSF outer sheath.

1.21.13 Cable installation All cables shall be laid in preformed trenches, in ducts or supported on racks and trays.

CCGT Contractor shall co-ordinate all cable installation work and construction interface activities with the Engineer and the Company (SEC) as necessary for successful completion of all interface activities.

Concrete encased PVC duct banks shall be used for installing cables in the outdoor area. MV cable duct banks shall be completely separate from the duct bank of LV cables. Hot dipped rigid galvanized steel long radius elbows shall be used at all stub-ups. The conduit shall exit the grade in the vertical plane with no part of the radius exposed. Cables rising out of duct through the floor shall be protected for a minimum of 1.5 m above the finished floor level. For above-ground cable installation, RGS conduit shall be used. Direct buried cables are not acceptable.

Above ground cable cellars are not acceptable.

A grounding conductor of 120 mm2 shall be laid along the duct bank and connected to the main ground grid. All cable tray supporting structure inside manholes shall be connected with duct bank grounding conductor.

The cable installation shall take account of the minimum bending radius of each cable as defined by the cable manufacturer.

The power and control cables associated with each station system shall be routed along a different path to other station systems. Alternatively, if different routes are not practical, then each system shall have significant separation or be segregated by fireproof barriers having a 1 hour fire resistance.

Equipment required for emergency use shall be cabled using routes that are different to, or segregated from, the routes used for normal running equipment.


Page 35 of 42

Single core cables run in trefoil shall be cleated using non-magnetic trefoil cleats which shall be capable of withstanding forces produced under short circuit conditions.

Cable trays, ladder racks and supports shall generally be heavy duty galvanized mild steel.

To enable complete redundancy to be maintained, two separate routes shall be used for the data highway.

Preformed trenches shall be of adequate size to allow for cable trays or ladder racks to be installed on the side of the trenches. The trenches shall be complete with accessible concrete covers with a removable steel inspection cover at the centre for inspection/maintenance of the cable trenches. Trenches shall be complete with sump pumps, heat detector cable and all necessary protection equipment.

Cables with a diameter of 15 mm or less shall be supported on cable trays. Ladder rack shall be used for cables with a diameter larger than 15 mm.

Control cables shall not be run on the same tray or ladder as power cables.

Steel cable ties shall be used for vertical runs of cable. PVC and nylon tie wraps shall not be used on horizontal runs which are in direct sunlight.

PVC shrouds shall be provided over all cable glands.

Cable lugs shall be the compression type.

Covers shall be provided for trays and ladder rack where the cables are in direct sunlight.

Cores of all control cables shall be long enough to allow a second termination at a future date.

Screens on multicore cables shall be insulated from field instruments and cable armour and shall be connected to ensure continuity throughout their length.

All cables and cable cores shall be unambiguously identified.

All shall be supported throughout their length, on either side of bends, and within 300 mm of the termination.

Wiring ferrules shall be suitable for affixing to the cable cores.

All steel conduit along with all accessories and fixings shall comply with IEC 60423 and IEC 60614. Minimum conduit size shall be 20 mm2. Conduit shall be hot dip galvanized, fittings shall be galvanized malleable iron.


Page 36 of 42

All ducts and conduits shall have their ends sealed against the ingress of water and oil.

Conduits and ducts shall be sized to enable the cables to be easily drawn in.

Cable trunking shall be manufactured from galvanized mild steel. The coating shall comply with ISO 1461.

The trunking shall be provided with removable covers.

Copper bonding links shall be fitted across all trunking joints.

Where cables pass horizontally through walls or vertically through floors and ceilings non-combustible, non-metallic fire barriers shall be installed.

A dedicated duct bank and premise distribution system for the communication system shall be constructed as outlined in Volume II, Section E.

1.22 Electrical equipment for hazardous areas The installation design, and the manufacture, certification and installation of electrical

equipment in hazardous areas shall comply with IEC 60079. All hazardous areas shall be shown on site layout drawings.

1.23 Lighting and small power

a] General

a. The whole system as well as the individual apparatus shall comply, if not stated otherwise, with the requirements of General Technical Requirements of Electrical works.

b. CONTRACTOR shall submit calculations to include, as minimum luminance levels, voltage drops, wire sizing etc. The maximum voltage drop between the transformer and the fittings shall be limited to 3 per cent of nominal voltage.

c. All equipment shall be suitable for continuous operation of a full range of ±10 per cent of the rated voltage.

d. All the lighting transformers shall be sized to have at least 25 per cent of spare capacity after final acceptance of the project.

e. Boards, sub-boards, and lighting shall have also 20 per cent of installed spare bus bars for future use.


Page 37 of 42

f. The current rating of switches and breakers to be used for main boards and sub-boards shall be determined according to the loads, however the minimum rating shall be:

a. 8-amps for lighting branch circuits,

b. 16-amps for outlets branch circuits.

g. The type of switches shall be mini-circuit breakers.

h. The connected load on lighting branch circuits shall not exceed 2000 watts or not more than 8 lighting fixtures per circuit.

i. Outlets shall be connected to separate branch circuits with not more than 8 outlets per circuit.

j. The sizes of the cables for lighting branch circuits shall not be less than

k. 4sqmm and 2.5sqmm to individual lighting fixture from lighting branch circuits.

l. The sizes of the cables for outlets branch circuits shall be not less than 4sqmm.

m. The rated source voltage for lighting and outlet units shall be as follows:

a. 380/220V, 60Hz neutral directly grounded

a. 220/127V, 60Hz neutral directly grounded

b. 125 V DC for emergency lighting.

n. The CONTRACTOR shall prepare and submit construction (installation) drawings to the COMPANY Engineer for approval. Drawings shall be prepared showing, location of light source, lighting panels and switching points, panel schedules, single line diagram and loading tables showing phase balancing and fixture schedules.

o. CONTRACTOR shall also ensure that all lighting fixtures and outlets are of highest quality, suitable for use with lamps commercially available subject to COMPANY Engineer approval. All equipment shall be suitable for continuous operation at +10 per cent of the rated voltage.

p. CONTRACTOR shall ensure the mounting position of lighting fittings and other items in the installation shall have safe access and control and accessible for repair and maintenance. When the above requirements are impracticable, separate proposal shall be submitted by the CONTRACTOR subject to COMPANY Engineer approval. For all lighting fittings installed 6meters or more above floor level, permanent means of access shall be provided.


Page 38 of 42

b] Distribution boards

The front door of the distribution boards shall be provided with lockable handles. There shall be one key type only for all sub-distribution boards. The protection class shall be IP-21 for the boards installed indoor and IP55 if installed outdoor. A diagram describing the circuits, which are connected to the individual fixed mounted outgoing feeders (MCBs), shall be provided on the backside of the front door. Lighting sub-distribution boards shall be made of 1.5 mm thick sheet steel, and the arrangement of equipment shall be such as to ensure satisfactory performance and shall allow sufficient space for proper maintenance. All outgoing feeders for the lighting and socket circuits shall be provided with miniature circuit breakers equipped with thermal and magnetic over-current release. The tripping characteristics of the (MCBs) shall ensure selectivity with other protection releases connected in series.

c] Illumination Levels

i. The minimum illumination levels after 100 hrs of operation shall be as follows:

a. Street lighting :30 lux

b. Site Perimeter Fence :40 lux

c. Outdoor transformers, Transformer bay, Fuel Pumping area :150 lux

d. Oil and water storage tank areas :50 lux

e. Outdoor operating areas :150 lux

f. Accessible cable trenches, manholes with fixed cover :50 lux

g. Turbine hall, indoor transformers, corridors, stair cases, basements, storerooms, machine rooms. :200 lux

h. Machine rooms, switchgear rooms :250 lux

i. Access ladder and Platform :50 lux

j. Relay rooms, workshop :250 lux

k. Control rooms, offices :500 lux

l. Warehouse :250 lux

m. Workshops :350 lux

n. Operating platforms :200 lux

o. Battery rooms, battery charger areas, UPS area. :250 lux

p. Computer rooms :500 lux

q. All indoor areas not specified :200 lux


Page 39 of 42

r. Toilets and washrooms :250 lux

s. Entrances / exits etc. :200 lux

t. Roads :30 lux

u. Car-parking :150 lux

v. Deep well area :150 lux

The uniformity factor shall be at least 0.70.

d] Service Voltages:

i. The following service voltages are as follows:

a. Normal lighting system:3-phase, L1, L2, L3, PE, N 480/380/220V, 60Hz

b. Emergency lighting system: 125V DC

c. Security lighting system: 3-phase, 4-wire, 480/380V/220V, 60Hz

d. A.C. socket outlets : single phase, 3- pins, 480/380 V/220V, 60Hz

e. Power socket outlets:

1st. single phase, three pins,127V, 60Hz

2nd. 3-phase four wires 480V, 60Hz

3rd. 3-phase, five pins, 380/220V, 60Hz

ii. The power socket outlets shall be fed directly from the LV power distribution, supplying the concerned area.

The lighting and socket systems main distribution shall be fed from the main lighting distribution board. Sub distribution boards shall be installed at locations approved by COMPANY Engineer . Required cables, conduits, supports and connections are to be provided by the CONTRACTOR.

Two systems of emergency lighting shall be provided. A section of the main lighting installation shall be operated as an emergency lighting scheme to comply with DIN 5035. The emergency lighting shall be automatically energized on failure of the electrical supply to normal lighting in the relevant area. Self-contained emergency light fittings shall be used in those outbuildings where no emergency lighting system exists. Emergency lighting shall be provided for all buildings. The type of fittings shall be similar to those used for the SCGT plant and associated buildings.

Socket outlets shall comply with IEC 60309 and shall be installed to give adequate coverage of all buildings and plant included in this Specification. Lighting boards shall supply the 220V outlets and 480V outlets shall be fed from the 480V AC auxiliary's switchboards. The 220V outlets


Page 40 of 42

shall be independent of the lighting circuits. The coverage afforded by the socket outlets shall be the same as that provided for the SCGT plant and associated buildings.

e] Emergency lighting

A section of the main lighting installation shall be operated as an emergency lighting

scheme to comply with EN 50172, EN 1838 and BS 5266-1.

The emergency lighting shall be automatically energized on failure of the electrical supply

to normal lighting in the relevant area.

The supply shall be from a separate emergency lighting DC system.

Self-contained emergency light fittings shall be used in those outbuildings where no

emergency lighting system exists.

The general levels of illumination in the Central Control Room shall not fall to a value less

than 100 lux under emergency conditions.

In areas where operations are necessary under emergency lighting conditions, the

illumination level shall at all times be consistent with the continuity of such operations. In the remaining

areas, including those of general access, the level of illumination shall be such as to ensure the safety

of personnel at all times.

1.24 Interfaces with substation CCGT Contractor shall co-ordinate all work and construction interface activities with the

EHV Substation Contractor and the Company (SEC) as necessary for successful completion of all interface activities for 380kV. The work to be done relates to the interface with the EHV substation is as listed below, but not necessarily limited to the following:

a. CCGT Contractor shall provide all necessary XLPE power cables, EHV and HV cable laying, termination and their arrangement between the generator transformer/ to 380kVsubstation bays.

b. CCGT Contractor shall coordinate with substation Contractor in preparing the bushing CT cable layout and installation for the protection of 380kV interconnection link. The CT cables (two circuits) shall run directly from 380kV bushing CT cores of generator transformers to differential protection relay equipment at 380kV Substation.

c. The procurement and installation of the required CT cables (10 mm2) shall be the responsibility of CCGT Contractor. CCGT Contractor shall provide the required


Page 41 of 42

duct banks and it is essential to make the current transformer cable layouts between the bushing current transformers of Generator to respective protection relay equipment at substation to less than 750 meters for each current transformer circuit.

d. CCGT Contractor shall co-ordinate with Substation Contractor for required VT signals.

e. CCGT Contractor shall co-ordinate with Substation Contractor for incorporating the tariff metering signals and summation of these in the DCS supplied by SCGT Contractor.

f. CCGT Contractor shall provide all necessary data for transformers, generators such as ratings, impedance, open circuit and short circuit characteristic curves and generator output system voltage system to Substation Contractor, as necessary.

g. CCGT Contractor shall co-ordinate with Substation Contractor and SCGT Contractor in order to connect all the tripping functions from the protection at the power station for steam turbine generator and generator transformer which necessitate tripping of circuit breaker at the substation. All transfer trips shall be through the communication terminal MUX provided at the communication equipment room in Central Control Building.

h. CCGT Contractor shall provide interfacing panel for each generator and generator transformer including necessary terminal blocks with isolating links, auxiliary relays, contact multiplication relays, lock out relays and cabling etc. required for tripping of EHV circuit breaker.

i. CCGT Contractor shall coordinate with the Substation Contractor and connect all required inputs including VT signals from substation marshalling panel for synchronizing of 380kV Circuit Breaker and for RTCC panel.

j. CCGT Contractor shall provide required cabling connections for trip signal from generator protection panel, generator transformer protection panel, generator transformer local control panel (mechanical relays) and station transformer protection panel to trip the EHV circuit breaker.

k. CCGT Contractor shall provide all necessary cabling between the power plant interfacing panels and substation marshalling panels for power plant requirements.


Page 42 of 42

Electrical Spec _site 26 Sep 2010_ Oct 10 (4)

Documents

Transcript of Electrical Spec _site 26 Sep 2010_ Oct 10 (4)