b7 electrical works

8/6/2019 B7 Electrical Works

1/53

B7Electrical and Associated Works


2/53


3/53

II

B7.3.5.1 Diesel engine and auxiliaries ............................................................. 7-33

B7.3.5.2 Control and monitoring equipment .................................................... 7-34

B7.3.5.3 Diesel Generator................................................................................ 7-35

B7.3.6 Cables and cable supporting structures .............................................. 7-36

B7.3.6.1 Cables ............................................................................................... 7-36

B7.3.6.2 Cable supporting structures ............................................................... 7-36

B7.3.6.3 Terminal boxes and local control boxes ............................................. 7-37

B7.3.7 Lighting and small power installations ............................................... 7-37

B7.3.7.1 Lighting system .................... ......................................... .................... 7-37

B7.3.7.2 Power socket combinations ............................................................... 7-41

B7.3.7.3 Portable isolating transformers .......................................................... 7-42

B7.3.8 Grounding and lightning protection installations .............................. .. 7-43

B7.3.8.1 Material ............................................................................................. 7-43

B7.3.8.2 Earthing system .................... ......................................... .................... 7-43

B7.3.8.3 Lightning protection system .............................................................. 7-45

B7.3.9 Fire alarm system .............................................................................. 7-46

B7.4 Technical Schedules ......................................... ......................................... .. 7-50


4/53

B7-1

B7. Electrical and Associated Works

B7.1 General

This specification covers the design, manufacturing, supply, erection,

commissioning and handing over of the electrical systems for the Keban

Agung Power Plant in South Sumatera Province in Indonesia, consisting of

two (2) units with a capacity described in B0.

The following equipment is under the scope of supply:

Transformers,

Medium voltage switchgear,

Low voltage switchgear,

DC and safe AC switchgear, batteries, rectifiers, inverters, DC-DC-

converters, Emergency power supply system,

Cabling and wiring, cable supporting structures,

Small power and lighting installations,

Grounding and lightning protection,

Fire alarm system.

The scope of the whole project covers the following electrical systems

A electrical works for the Power plant (-the facility-)

B electrical works for the Interconnection facilities, covering theconnection to the 150 kV transmission line

For all electrical works for the Power plant, the contractor has to fulfill

requirements set by the utilities, among others the PT. PLN (Persero)

(TRANSCO) Transmission Code whenever it is applicable to the plant

equipment.

The electrical equipment to be provided shall be suitable for faultless and safe

operation of the entire plant during all phases of operation and shall be

suitable for the location in which they shall be mounted.

The Contractor must adhere to the functional requirements, design criteria

and system configuration contained in this document. Where there is a

conflict between the requirements of this specification and the Contractorscurrent standard system/technology, this must be clearly defined in writing

as a deviation to the specification. The Contractor may propose alternative

improved performance features as long as the system is made up of power

plant proven equipment and components, hardware and software modules.

B7.1.1 Electrical system design

The power plant units will be connected to the public utility network of PT.

PLN (Persero), TRANSCO.


5/53

B7-2

The power of the turbine generators will be stepped up by a generator

transformer and, via overhead line connections, be transmitted to a new

150 kV switchyard, which is connected to the public network of

TRANSCO, Indonesia.

Power for start up and shut down will be provided from the 150 kV network

via the generator transformers and unit auxiliary transformers, but also shall

be possible from the unit auxiliary transformer of another unit via the unit

interconnections or via an optional black start facility.

After start up and synchronization of a unit the auxiliary power is supplied

by the turbine generator via the unit auxiliary transformer.

Unit related auxiliaries will be supplied from unit related switchgear,

common auxiliaries will be supplied from a common auxiliary busbar.

The electrical system within the power plant shall be controlled andmonitored through the DCS from the central control room (CCR).

The electrical equipment shall be designed according to the IEC standards

(if not specified otherwise) and shall fulfill the requirements of the

TRANSCO Grid Code and local laws and regulation.

Unit related auxiliariesPower to the 6.3 kV unit switchgear will be fed via the unit auxiliary

transformers, either from the turbine generator (during normal operation), or

via the generator transformer from the 150 kV network (during start up and

shut down).

The 6.3 kV switchgear will provide power for:

Medium voltage transformers for 6.3 kV consumers

Low voltage transformers for 0.40 kV consumers

Large motors ( 1500 kW)

Common auxiliary busbar

Motors > 200 kW will be supplied by a 6.3 kV medium voltage system,

which will be fed in via 13.8/6.3 kV transformers. Motors < 200 kW and

other electrical consumers will be supplied by the 380 V low voltage

system.

The 0.40 kV unit switchgear consists of main distribution, with two half-

busbars normally fed via two infeeds.

The 220 V DC main distributions are fed by 2 x 100% rectifiers and 2 x100% batteries.

The 220 V DC system supplies the switchgear control, annunciation and

monitoring system, the emergency oil pump for turbine bearing lubrication,

other auxiliary drives, inverters DC/DC converters and emergency lighting.


6/53

B7-3

The 230 V Safe AC system comprises an inverter with static bypass switch

unit and a safe busbar. The inverter is supplied via coupling diodes from

both sections of the 220 V DC main distribution. The static bypass switch is

supplied from the 0.38 kV switchgear.

The 230 V Safe AC system supplies the equipment requiring uninterrupted

supply (UPS) e. g. measuring and control system, control actuators,

recorders, flame monitors, emergency valves, VDU.

The 220/26 V DC/DC converters serve as supply for I&C cabinets and other

consumers requiring 24 V DC supply. Each DC/DC converter is supplied

via coupling diodes from both sections of the 220 V DC main distribution.

All the required auto transfer between the busbar shall be provided.

Common auxiliaries

Common auxiliaries (e.g. auxiliary cooling water, water treatment, coalhandling, fire fighting system) will be supplied via 6.3 kV common

auxiliary switchgear. Metering systems shall be provided to separately

determine the common auxiliaries power consumption supplied from each

unit 1 and 2.

In general, the design and arrangement of the common auxiliary system is

similar to that of the unit related auxiliaries described above. However loss

of any infeed/supply shall not cause loss of any of the power units. All

required automatic transfer systems shall be provided. The main

components are:

6.3 kV switchgear with two bus sections

Low voltage transformers

0.40 kV switchgear

Emergency diesel generators

220 V DC system

230 V UPS system

220 V / 26 V DC/DC converters.Each section of the 6.3 kV common auxiliary switchgear will be fed from

one of the 6.3kV unit auxiliary switchgear of Unit # 1 and Unit #2.

Each 6.3 kV and 0.40 kV switchgear of the common auxiliary system

consists of a main distribution with two sections and an automatic transfersystem. The switchgear shall be fed from the 6.3 kV common auxiliary

switchgear via 2 x 100% transformers.

The emergency diesel generators will be sized to supply all essential loads

in case of a "black out" to shut down the plant safely.

For the administration building and workshop/store buildings separate 1 x

100%, low voltage transformers and related switchgear shall be provided (if

required).


7/53

B7-4

Back up supply shall also be provided to the switchyard for the switchyard

lightings.

B7.1.2 Mode of operation

The following modes of operation shall be considered.

Generation modeThe main mode of operation shall be to dispatch electrical energy into the

public grid as required by the TRANSCO Load Despatch Center.

In general, the requirements of the TRANSCO Transmission Code have to

be fulfilled in addition to the specified requirements herein.

The main part of the power generated by the turbine generator of the plant is

fed into the public utility grid, while the other part is needed for the

auxiliary demand of the plant.

Start-up modeFor start-up of the power units, it will be necessary to import power from

the grid. The power imported will be fed via the generator transformer and

the generator main connection which energizes the unit auxiliary

transformer. When the generator is synchronized to the grid and sufficient

electrical energy is available, the system can be placed into generation

mode.

However, in case of one or two units already operating, it shall be possible

to start another unit from one of the running units. The following equipmentshall be designed to cover the load of the related unit, common load and

start-up power of one additional unit:

Unit auxiliary transformers of Units #1 and #2

6.3 kV unit auxiliary switchgear of Units #1 and #2

The required 6.3 kV feeders including load transfer systems shall be

provided in the three units. 6.3kV cable interconnections between the three

units shall also be provided.

Mode of operation without turbo generatorThis mode of operation may occur if the generator trips during part or full

load operation of the plant. In such a case immediately the energy flowthrough the generator transformer will reverse and energy will be imported

from the public grid.

Mode of operation without the 150 kV grid

There are two cases to be considered:

a. At least one turbine generator is in operation in case the 150 kV

circuit breaker opens the unit will make a load rejection to the

minimum plant load and will operate in island operation. After grid


8/53

B7-5

voltage recovery, a quick re-synchronization of the unit is possible

via the 150 kV circuit breaker.

b. No turbine generator is in operation

Please refer to "Blackout mode of operation".

Blackout mode of operationA total Blackout occurs when there is an unexpected power cut on the

public utility grid and there is also no electrical power output from the turbo

generators at the plant.

Under such conditions, the critical loads like the DC consumers, turbine

emergency oil pump, computers and I & C auxiliaries will continue to

receive their uninterrupted power supply from the DC batteries and

inverters.

When the blackout occurs, the in-house diesel generators will start

automatically to supply its relevant load within 30 seconds.

The emergency power supply program will be switched in automatically by

the DCS and power feed to the rectifiers, batteries, the inverters and all

other essential loads will be restored.

The emergency diesel generator will only maintain the necessary essential

services during the shut down of the plant, but its power is not sufficient to

start up the system in case of black-out.

Power unit out of operationIf the power unit is out of operation, it shall be possible to supply the

required auxiliaries via one of the generator and unit auxiliary transformers

of Unit #1 or Unit #2.

B7.1.3 Arrangement of electrical equipment

The connection between the generator and the generator transformer as well

as the unit auxiliary transformer shall be carried out by fully insulated single

phase busbar connection systems. The turbine generator starpoint

connection shall also be of the fully insulated busbar type.

The generator transformer and the unit auxiliary transformer are located

outdoor at the side of the turbine hall, separated from each other by a fire

protection wall.

The high voltage connection at the generator transformer HV bushings is

made by buried line conductors, which connect the transformer to the new

150 kV GIS, located in a substation of the power plant.

In general, the unit related electrical equipment (switchgear, station service,

transformers, DC- and UPS systems) shall be installed in unit related

electrical rooms, located in the bunker building at the lower levels. Hence

short cabling distances to all load centers of the units is maintained.


9/53

B7-6

Electrical equipment for common use will be installed mainly in the lower

levels of the central control building or in local electrical rooms.

Local electrical rooms for station service transformers, switchgear and

subdistribution panels in other areas of the power plant shall be provided asrequired mainly for the common auxiliary systems (e.g. for coal handling,

cooling water intake, water treatment plant, etc.).

Electrical rooms will be forced ventilated.

B7.1.4 Basic electrical design criteria

The following general design criteria have been assigned to the basic

planning of the electrical system.

The electrical system shall be designed in such a way that the outage of

one component does not require the shutdown of the associated unit Redundancy of electrical plant shall strictly follow the redundancies

applied for mechanical equipment

Electrical equipment chosen shall be selected so that types and ratingsare in line with mass-produced electrical equipment, to be purchased

easily at the free market, with long-term secured spare parts availability

Maintenance-free, easy-to-service equipment of the modular,interchangeable type like motor control centers (MCC), gas-tight

batteries, shall be used

Major electrical equipment shall be type tested and certified by approvedtesting authorities.

B7.2 Scope of supply and services

B7.2.1 General

This section sets out the scope of supply of the installations covered by this

specification as well as requested supplies and services, but without

excluding other necessary components and services not mentioned.

The complete electrical equipment will be designed according to IEC

regulations or equivalent standards which fulfill at least the IECrequirements (if not specified otherwise elsewhere).


10/53

B7-7

B7.2.2 Scope of supplies

B7.2.2.1 Main scope of supply

Transformers 2 (two) generator transformers, 2-windings type, with on-load tap

changer and automatic voltage regulator

2 (two) unit auxiliary transformer 13.8kV / 6.3 kV, 2-windings type,

Several low voltage station service transformers 6.3 kV / 400 V forcommon auxiliaries (2 x 100%),

Several unit related low voltage station service transformers (2 x 100 %)

Separate low voltage station service transformers for the administrationand workshop/store building (if required).

Surge arrestors at generator transformer HV side

Transformer spray high pressure water systems, complete for generator

and unit auxiliary transformer All required transformer neutral earthing resistors for the 13.8 kV and

6.3kV system

Gas-in-oil on-line transformer condition monitoring system as specifiedin Section B7.3.1.1 for generator and unit auxiliary transformer

Medium voltage switchgear (6.3 kV system)

2 (two) 6.3 kV unit auxiliary switchgear

1 (one) 6.3 kV common auxiliary switchgear

6.3kV subdistributions, as required

to be equipped with plug-in or draw-out type power switching devices

Vacuum type circuit breakers with 220 V DC motor-driven stored energymechanism for power infeeds, transformer and large motor outfeeds, bus

couplers

Vacuum contactors with HV fuses for smaller motor outfeeds

Digital control and protection relays

High speed automatic transfer systems (as far as required)

The switchgear will also contain:

Subframes for mounting of the switchgear cubicles

Cable paralleling arrangements in separate steel-clad cubicles with

auxiliary busbar systems, connecting bars and support structures togetherwith a sufficient number of earthing studs, for all feeders with more than

two parallel cables per phase.

Monitoring and signaling equipment, mini circuit breakers for protectionand voltage transformer, switch position indicators, reporting and

operating facilities, mimic diagram

Relay recess with the protection and monitoring relays, coupling relays,mini circuit breakers, complete terminal boards, meters etc.

1 (one) fully equipped spare switchgear cubicle, however without thewithdrawable truck or module.


11/53

B7-8

Low voltage switchgear

Several 0.40kV unit main distributions, each with two sections

Several 0.40kV unit subdistributions,

Several 0.40kV common auxiliaries main distributions each with two

sections, Several 0.40kV common auxiliaries subdistributions,

Minimum 5 (five) percent fully equipped spare capacity and 10 % spareterminals at the date of handing over,

Separate 0.40kV distributions and subdistributions for the administrationand workshop/store building (if required).

The switchgears will also contain:

The relay recess with the protection and supervisory relays, completeterminal arrangements, meters etc.

The connection compartment with current and voltage transformers,

cable sealing ends, etc.

All circuit breakers will be equipped for remote operation. Local control atthe switchgear will also be possible.

DC system, inverters and associated equipment

220 V unit related batteries, nickel-cadmium,

220 V unit related rectifiers,

Minimum 1 (one) 220 V DC system for common auxiliaries consisting of2 x 100 % NiCd batteries, 2 x 100 % rectifiers and distribution,

6 (six) 240 V unit related inverters with static bypass switch and manualbypass,

3 (three) 220 V DC unit related main distribution, 3 (three) 230 V Safe AC unit related distributions,

Minimum 1 (one) 240 V safe AC system for common auxiliariesconsisting of 2 x 100 % inverter with static and manual by-pass switch

and distribution

Several 220 V/26 V DC/DC converters,

At minimum 5 (five) percent fully equipped spare capacity and 5 % spareterminals at the date of handing over.

Emergency AC power supply system

As a minimum 2 (two) emergency diesel generators complete :

Diesel engine, water-cooled, with exhaust gas turbo charger, Fully pressure-lubricated system,

Fuel supply and injection system including day tank (only if required)

for 20 h unrestricted full load operation and refilling from the LFO

common tank,

Air intake and exhaust system with exhaust gas pipe and silencers

according to local regulations,

Control and monitoring equipment for normal operation, start-up and

shut-down,

Synchronous generator complete with:


12/53

B7-9

Excitation system,

Generator protection,

Automatic synchronizing unit,

Completely equipped container for housing the emergency diesel

generator set, if not installed in a separate building.

Cables and cable trays(According to the description in section B0 Electrical Equipment and

Works)

Supply, laying and connection of power, control and measuring cablesfor power plant specific equipment including all accessories and

supporting structures

Supply and installation of all terminal boxes and cabinets,

Supply and installation of all local control and level control boxes,

All necessary fixing materials,

All necessary fire protection materials for closing the cable openingsthrough walls and ceilings as well as between switchgear and control,

measuring and switchgear cubicles, operating panels and desks, etc.

All necessary plastic protecting tubes for the cable runs,

All necessary cable connections including compression cable lugs

All necessary materials for laying the cables in the ground,

Fixing and clamping materials etc,

All necessary cable sealing ends and cable connecting sleeves includingfixing materials,

All necessary compression connectors,

All necessary number plates for identifying the cables.

Small power and lighting installations

The necessary lighting subdistribution units for internal and externallighting,

The necessary emergency lighting distributions,

The necessary lighting fixtures and installations for the internal lighting,external lighting and street lighting,

Any necessary fittings and installations for the emergency lighting,

Foundations and poles for street lighting,

Any necessary connecting and attachment materials for the wholelighting system,

Complete security lighting system around the entire plant site

Aircraft warning lights

The complete power socket system including, but not limited to:

All necessary domestic power outlets,

All necessary power sockets each with 1 x 63 A, 1 x 32 A and 2 x 16 Asockets,

All the necessary power sockets 1 x 125 A,

All the necessary material required for installation of the sockets.

Isolating transformers for the purpose of producing the protective lowvoltage for work in metal enclosures, boilers, tanks, etc.


13/53

B7-10

Grounding and lightning protection

The necessary lead-sheathed stranded copper cables for the outdoorearthing installations,

The necessary tinned stranded copper cables for indoor earthing

installations, The necessary galvanized steel bars for the earthing ring inside the

buildings,

The necessary round iron (reinforcement bar) inside the concreteincluding flexible PVC single-core cables for being laid out of the

concrete,

The necessary compression connectors or connections by Cadweldsystem for the earthing conductor crossing point connections and

junctions,

All connections to the housings of the electrical apparatus, steel frames,pipes, steep strips, etc,

All necessary disconnecting points for measuring purposes which mustbe readily accessible,

All the necessary lightning protection equipment for the protection ofpersons and structures such as lightning collectors, roof bushings, stack

rings, chimney safety ladders, lightning rods, potential equalizing

systems, spark gaps, lightning arrestors, etc.

The required connecting and fixing material.

Fire alarm system

Fire alarm central station,

Display board in the central control room,

Automatic fire alarm detectors,

Pushbutton fire alarms, Sirens,

Complete cabling and wiring, suitable for fire alarm line cabling,

Tools and GaugesThe contractor shall supply all necessary special tools and gauges required

for maintenance. This should also include tools required for inserting and

racking out the withdrawable gear. A lockable metal clad tool box shall be

provided and installed in the switchgear room to house the tools of the

switchgear.

B7.3 Special Technical Requirements

The requirements specified in Section B0 General Technical

Requirements are to apply, where applicable as well as further regulations

from other sections of this specification.


14/53

B7-11

B7.3.1 Transformers

B7.3.1.1 General

The rated output of the generator transformer shall be defined by theContractor as follows:

SGT = SGenMCR - SUnit Aux.

The rated output of the unit auxiliary transformer for Unit #1 and #2 shall be

defined by the contractor as follows:

SAux = SUnit Aux - Sgen Aux.

The rated output of the unit auxiliary transformer for unit 3 shall be defined

by the contractor as follows:

SAux = SUnit Aux.

SGT: Rated output of Generator Transformer in MVA

SGenMCR: Maximum continuous rating of generator at nominal lagging

power factor in MVA

SUnit Aux.: Power requirements of one unit related auxiliaries

(not including power requirements for the general auxiliaries)

in MVA.

SAux. : Rated output of unit auxiliary transformer in MVA

SGenAux: Power requirements of general common auxiliaries at thefinal configuration of the plant (3 power units) in MVA

The capacity of the unit auxiliary and station service transformers shall be

matched to the relevant auxiliary power requirements, under consideration

that with maximum basic load and start-up of the largest motor the voltage

drop at the busbars will not exceed 10%.

The transformer tanks, radiators and control and monitoring cabinets are to

be spray galvanized. An alternative painting system or an oil resistant

coating of tanks and radiators will be accepted as well.

The transformers shall comply with the IEC regulations, in particular IEC60076 for design, manufacturer and test and IEC 60214 for tap changers

testing.

Main transformer condition monitoring system

An approved transformer on-line condition monitoring system shall be

implemented to show the momentary condition of the cooling oil

composition as well as long term trends.


15/53

B7-12

At least the following functions shall be included:

Gas-in-oil monitoring

gas-in-oil monitor of approved type i.e. HYDRAN-Sensor, sensor and

digital transmitter in single enclosure

Necessary valves, pipes, anti-vibration mounting racks

Complete cabling and wiring from sensor to terminal blocks up to theconnection to the data analysator set

Computer-aided data analysis with laptop or external personal computer

including application software and accessories.

Monitoring shall be performed on the generator and on the unit auxiliary

transformer.

Data analysis shall be provided centrally by networking the individual

sensors.

The Tenderer is requested to propose any other monitoring functions, which

he deems necessary.

B7.3.1.2 Generator transformer

The generator transformer has to be designed as three-phase power

transformer for outdoor installation.

Transformer cooling shall be preferably of the ODAF/ONAN principle.

On the higher voltage side the transformer shall be connected by means of

buried line conductors to GIS and from there, via buried line, to the 150 kV

tower end in the Plant.

The high voltage bushings shall be provided with current transformers

(minimum 3 cores) for protection (transformer) and measuring.

The transformer neutral on the high voltage winding shall be resister

grounded.

The HV neutral bushing shall be equipped with current transformer

(2 cores) for over current and ground fault differential protection and surge

arrestors.

The low voltage side is to be equipped with connection flanges and aconnection frame to connect an isolated-phase generator main connection.

Oil- and winding temperature monitoring devices shall be provided.

The transformer shall be provided with motor-driven on-load tap changer.

The instruments and equipment necessary for tap changer control,

temperature-dependent control and monitoring of the transformer and of the

cooling system are to be housed in a cabinet to be mounted on the


16/53

B7-13

transformer. The necessary control and monitoring signals are to be wired to

terminal strips for remote control and monitoring through the DCS.

Each generator transformer shall be equipped with an automatic voltage

regulator (AVR) as specified in Section B7.3.1.6.

The AVR shall be active only if the generator circuit breaker is in OFF

position.

B7.3.1.3 Unit auxiliary transformer

The unit auxiliary transformer shall be designed as three-phase, three

windingtransformer for outdoor installation.The transformer shall be provided with flanged-on radiator cooling which is

of the ONAN/ONAF principle.

The high voltage side shall be equipped with connection flanges and a

connection frame to connect an isolated-phase generator main connection.

On the low voltage side a metal-clad auxiliary busbar system is to be

provided to which the feed-in cables for the 6.3 kV voltage switchgear

will be connected.

The busbar system housed inside the metal cladding must be designed to

permit testing of the cable and transformer connections at fixed screw

connections.

The instruments and equipment necessary for the temperature control andmonitoring are to be housed in a cabinet to be mounted on the transformer.

The necessary control and monitoring signals are to be wired to terminal

strips for remote control and monitoring through the DCS.

A five-step off-load tap changer (2 x 2.5%) with manual drive mechanism

is to be provided. This shall be operated from outside and provision shall be

made for locking it.

B7.3.1.4 Station service transformers

Station service transformers (from 6.3 kV to 0.40 kV) shall be designed as

oil-cooled three-phase transformers. The cooling shall be of ONAN

principle. They shall be installed in transformer boxes in the immediate

vicinity of the medium or low voltage switchgear.

Cast-resin insulated dry-type transformers with suitable housing (protection

class minimum IP21) located indoor close to the L.V. switchgear may be

provided alternatively.


17/53

B7-14

Dry type transformers shall be provided with winding temperature

monitoring facilities.

The high and low voltage side is to be equipped with a metal-clad auxiliary

busbar system to which the input and output cables can be connected.

An off -load tap changer is to be provided on the high voltage side.

This will be operated from outside and must be capable of being locked.

The station service transformers shall be designed so that with the whole

plant running at full load, the transformers will be loaded as follows:

80% in case of 1 x 100% transformers,

40% in case of 2 x 100% transformers.

B7.3.1.5 Transformer high pressure spray water system

The generator and unit auxiliary transformers shall be fitted with theequipment specified below:

One transformer high-pressure water spray system discharging on the

transformers. Each transformer shall be provided with one valve station and

one control and monitoring cabinet for the water spray system.

The water spray system shall be designed for manual, automatic or electrical

remote operation and shall be provided in free-standing and self-supporting

design, with the following basic equipment:

The required number of triggering and fire extinguishing nozzles, with

galvanized pipes and mountings, The necessary galvanized connecting lines from the appropriate valve

station to the nozzle pipe network,

The necessary drainage valves, struts, diaphragm sleeve valves, singlechamber valve stations with all fittings and connections, pressure-

sensitive switches for signaling and air pressure drop,

The necessary tank feed pump,

One brine control and monitoring cabinet, remote control from thecentral control room

A compressed-air, fire-fighting vessel for maintaining a reserve of fire-fighting water for a minimum spraying time of 5 minutes.

B7.3.1.6 Automatic voltage regulator

For detailed requirements regarding the voltage regulation, see also B0-

2.11.1 Voltage and Reactive Power Control.

The generator transformers shall be provided with an automatic voltage

regulator (AVR), for maintaining the voltage on the LV side within

adjustable limits.


18/53

B7-15

It shall be possible to select following operation modes:

Local electrical non-automatic

Remote electrical non-automatic

Remote automatic.

A digital type AVR of an approved design shall be provided. The set point

voltage shall be adjustable between 90% and 110% of the energizing

voltage.

The sensitivity of the AVR shall be suitable for adjustment at any value

between 0.5 % and 6% of the setpoint voltage.

A time delay adjustable between the limits of 10 and not less than 180

seconds shall be provided. This setting shall represent the maximum

operating time, which shall be reduced automatically as a function of the

amplitude and duration of the voltage deviation.

Additional, the AVR shall be blocked if the energizing voltage becomes too

low or too high. The low voltage blocking shall be adjustable between 70%

and 95% and the high voltage between 105% and 130%.

For remote control and equipment through the DCS all required interfacefacilities shall be provided. Remote automatic control shall be included into

the plant unit level automatic start up sequence control.

B7.3.1.7 Neutral earthing resistors

The transformer neutral (star) points on the 13.8kV and 6.3kV windings are

to be earthed through resistors. The earthing resistors shall be of rustless

unbreakable material installed in a metal enclosure for outdoor installation

and shall comply with the "General Technical Requirements" Section B0.

For interconnection with the transformer MV single core cables with

suitable cable terminal boxes (IPW55) shall be provided. The resistor and

the enclosure shall be designed in such a way that the surface temperature is

not dangerous for personnel.

B7.3.2 Medium voltage switchgear (6.3 kV)

The following technical requirements shall apply for the 6.3 kV switchgear.

B7.3.2.1 General

The switchgear shall be of metal-clad compartmented design for indoor

installation with draw-out type switching devices.

All incoming and outgoing feeders of the switchgear are to be equipped

with withdrawable modules for


19/53

B7-16

Circuit breakers (vacuum or SF6-type) with motor-driven stored energymechanism

Vacuum contactor with HV fuses (for smaller motor outfeeds)

Permanently installed short-circuit-proof /make proof earthing switches are

to be provided in the lower part of the switchgear cubicle and these are to belocked mechanically with the corresponding circuit breaker. In addition,

the earthing switches of the infeed panels are to be equipped with

interlocking relays wired to the terminal board in the relay recess preventing

closure of the earthing switches when the breaker at the remote end is

closed.

Bus bar earthing switches (short circuit proof/make proof) shall be provided

for each bus bar section.

In general, for all incoming and outgoing feeders requiring more than

2 parallel cables per phase, appropriate steel-enclosed paralleling

arrangements are to be provided. The cable sealing ends are to be fastenedside by side on a support structure in these steel enclosures. The connection

from the copper busbar paralleling arrangement to the switchgear cubicle is

to be made by short lengths of copper bar.

Earthing studs are to be provided in sufficient number on the copper busbars

for feeders without earthing switches.

Overvoltages on motor feeders which may occur in the event of switching

high voltage motors by vacuum contactors shall be prevented by suitable

measures (e.g. voltage limiters).

All circuit breakers must be lockable by padlock provisions in withdrawn

position.

Suitable automatic high speed transfer systems shall be provided between

the individual infeeds/bus couplers of the common auxiliaries switchgear.

Loss of one infeed to the 6.3 kV common auxiliary switchgear shall not

cause loss of any power unit.

BulkheadingThe individual cubicles are to be bulkheaded from one another by double

sheet metal partitions or approved equivalent system.

Within the cubicles, the compartments for circuit breakers, busbars,

instrument transformers and cable connections as well as the relay recesses

must be bulkheaded from one another. Sufficient pressure relief must be

provided for the case of fault arcs. For each bulkheaded compartment a

separate pressure relief must be provided. Care must be taken that in the

event of arcing no hot gases escape to the front of the cubicle (operational

side).


20/53

B7-17

Type test certificates by an approved testing authority shall be presented in

order to prove that the switchgear supplied is able to withstand fault arcs in

accordance with IEC 60 298, Appendix AA, criterion 1 to 6.

B7.3.2.2 Switchgear components

The switchgear and main equipment items shall comprise but not be

limited to:

Steel-clad, bulkheaded design, the various functional compartments(circuit breaker, busbar, cable connection and relay compartments) are

separated from one another by multiple bulkheading

Single copper busbar system

Withdrawable circuit breakers (vacuum type) with 220V DC motor-driven energy mechanism,

Withdrawable contactors or load break switches with HV fuses.

Provision are to be taken that when the switch is withdrawn, the insertioncontacts are automatically covered with sheet metal shutters so as to

prevent any danger of accidental contact

Withdrawable isolators with 220V DC motor operation for the start-upswitchgear

Universally interchangeable switchgear trucks or modules with definedtest position

Cable connection compartment with the necessary current and voltagetransformers, the make proof earthing switch, including the necessary

fixing for high voltage cables

Fuses and voltage transformers for busbar measurement and earth faultprotection

Relay recess with the protection and monitoring relays, coupling relays,measurement transducers, mini circuit breakers, complete terminal

boards, meters etc. including the illumination with fluorescent tubes

Mimic diagram on the front of each cubicle consisting of graphicalsymbol and position indication

Load transfer/high speed transfer system

Fire-proof closure to the floor of the switchgear panels to seal theoutgoing power cables

Plug-in type connections for all auxiliary contacts between fixed andwithdrawable part of switchgear.

Current and voltage transformersThe thermal withstand capability of the instrument transformers is to be

based on a disconnection time of min. 0.5 sec in the outgoing circuits to the

consumers and of min. 1.0 sec in the infeeds. All current transformers must

be mounted in the fixed part of the switchgear cubicle.

The instrument transformers secondary circuits must be wired individually

to the switchgear cubicle terminal strip. In case of current transformers,

the necessary terminals are to be equipped with short-circuit links. Cast-

resin insulated, corona-free transformers are to be employed.


21/53

B7-18

Current transformersAccuracy for metering class 0.5 M 5

Accuracy for measurement class 1.0 M 5

Accuracy for protection class 5 P 10

Accuracy for differential protection class 5 P 20.

The current transformers are to be designed capable to withstand the

dynamic and thermal short circuit stresses. Intermediate transformers are to

be avoided. For protection and measurement separate cores are to be

provided.

Voltage transformersAccuracy for measurement class 1.0

Accuracy for metering class 0.5

In infeed and measuring cubicles, three single-phase insulated voltage

transformers are to be used.

The secondary sides of voltage transformers are in general to be safeguarded

by mini circuit breakers. If the same voltage transformer is used for several

purposes (e.g. measurement, protection, metering) then individual separate

mini circuit breakers with auxiliary contact are to be provided.

Protection relaysDigital protection relays fitted with test facilities are to be used throughout.

The Contractor must ensure that the electrical plant is sufficiently protected.

All protection relays have to be selective.

As a minimum, the digital protection relays shall be provided as follows:

Infeeds and bus ties: Three-phase, dependent and independent(selectable between inverse time curves

and definite time ranges) over-current

time-lag relays with continuously

adjustable short circuit trip,

synchrocheck relays

Station service transformers: Two-phase, dependent and independent

(selectable between inverse time curves

and definite time ranges) over-current

time-lag relays, with continuouslyadjustable short-circuit trip.

Intertripping circuit between MV and

LV circuit breaker.

Transformer Buchholz protection


22/53

B7-19

High voltage motors: Instantaneous overcurrent, thermal

overload, locked rotor, ground fault by

rings core CTs.

Measuring cubicles: Three-phase earth fault measuring relays

for 6.3 kV switchgear undervoltagemonitoring relay (adjustable 50 .... 100%

voltage, 0.1 ..... 10 seconds time)

Mimic diagram and local indicationsA colored mimic diagram or an equivalent display and control unit is to be

provided on the front of each switchgear cubicle with the necessary

graphical symbols and indications, containing at least the following items:

Busbar

Breaker position indication

Breaker/ contactor operating buttons.

Earthing switch position indication

Transformer or motor symbol

Breaker position indicator for the switchgear installation being fed.

Additionally as status indication, fault annunciation

Switchgear truck in test position

Switchgear truck in operating position

Circuit breaker/load break switch/contactor tripped

Fault indication, e.g. no control voltage

no motor voltage MCB tripped.

Control of the switchgear installationsThe control of the circuit breakers/load break switch/contactor is to be

carried out with 220V DC and shall be:

Made available at least twice for each switchgear installation in themeasuring cubicle

Diode decoupled

Permanently wired from panel to panel

Safeguarded by MCBs in each panel

Tripping of MCBs shall be monitored and be indicated locally.

Each of the circuit breaker shall normally be controlled from remote, but

shall also be capable of being operated locally from the switchgear. If the

control voltage fails, the EMERGENCY OPEN operation of the switches

must be possible. In the test position of the truck, the circuit

breakers/contactors/load break switches must also be capable of being

operated locally and also remotely from the central control room.


23/53

B7-20

In the event of a protective trip of the circuit breaker/load break

switch/contactor, means must be provided to prevent reclosing which can

only be overridden again from the switchgear cubicle.

Mini circuit breakers are to be provided for:

Local controls, interlocks

Local annunciation and fault indications

Power supply to motor-driven stored energy mechanism.

The circuit breakers, contactors and load break switches of the switchgear

installations are also to be remotely controlled from the central control room

through the DCS.

Local measuring instrumentsAs minimum scope, the following measurements are to be provided locally:

Three-phase current indication in all infeeds and couplings

Single-phase current indication in phase L2 of all the outgoing feeders

Voltage indication moving coil type, cl. 1.5, with corresponding 4-wayvoltmeter selector for measuring phase L1 - N, phase L2 - N,

phase L3 - N, phase L1 - L3 in all infeeds and in the measuring cubicles.

A-meters shall be provided with one indicator for instantaneous currentindication (moving coil) cl. 1.5 with red mark at rated current and

maximum indicator with bimetallic moving cl. 3.0 and trailing pointer.

For each circuit breaker/contactor/load break switch:

Operation counter.

Remote indications and measurementsThe Contractor shall provide the following remote indications and

measurements to the CCR through the DCS:

Indications/Signals

Switchgear truck not available for operation (in test position or not run inas a group signal)

Earthing switch ON and OFF, each separate

Circuit breaker contactor/load break switch/isolator ON and OFF, eachseparate

Circuit breaker contactor/load break switch tripped through fault Miniature circuit breaker tripped (as group signal)

No control voltage (as group signal)

Earth fault

Protection activated (as group signal)

No busbar voltage

Voltage transformer mini circuit breaker tripped (as group signal).


24/53

B7-21

Measurements

Current (4....20mA) in all the infeeds (3-phase) and outgoing feeders(1-phase)

Voltage (4....20mA) in all infeeds and in the measuring panel (busbarvoltage).

B7.3.2.3 Automatic high speed transfer equipment

A high speed transfer system from one incoming feeder to the other

incoming feeder shall be provided for 6.3 kV common auxiliary switchgear.

The voltage and time safety margin before motor trip on undervoltage shall

match the residual voltage transfer and the process requirements.

The high-speed transfer system shall be started as follows:

Manually (local or remote through the DCS)

Automatic by protection relays.

Each high-speed transfer system shall comprise following:

Logical analyzer for all required control, interlocking and monitoringfunctions

Phase comparison device for continuously monitoring the phase angle,frequency and voltage

Test facilities for testing the complete transfer system up to the closingand trip coil of the circuit breakers whilst the system is ready for

operation.

According to the electrical system the high-speed transfer system shalloperate as follows:

High speed transfer - the opening and closing command issued at thesame time

Residual voltage transfer - the individual circuit breaker will be closed ata residual voltage adjustable between 20 and 50% of the rated voltage

Long time transfer - the circuit breakers are closed after an adjustabletime which insures that the residual voltage is lower than at the residual

voltage transfer.

If in case of a high speed transfer, the relevant circuit breaker does not open,

e.g. due to mechanical failures, the already closed circuit breaker shall betripped within an adjustable time.

The transfer shall be blocked in the following cases:

Short circuit on the relevant 6.3kV busbar

Incoming circuit breaker not in service conditions (withdrawn, spring notcharged, etc.)

MCB trip

Voltage on the stand-by source is not available


25/53

B7-22

If the feeding transformer will be overloaded.

Each high-speed transfer system shall be installed in free standing cubicles

with the required control and monitoring equipment on the front door (e.g.

remote heat selector switch, test push button, fault indicating light, etc.).

The control voltage shall be 220 V DC with double infeeds, diodedecoupling and voltage monitoring.

Synchro-check relays shall be provided to prevent the respective circuit

breakers from closing during synchronization while the plant's normal

supply and the diesel generator's supply are out of synchronization.

B7.3.3 Low voltage AC switchgear

B7.3.3.1 General

The 0.40 kV switchgear shall be designed as indoor switchgear installation

of sheet-steel-clad, bulkheaded type, in the plug-in principle.

The switchgear and the individual components shall comply with IEC

60439, IEC 60044, IEC 60186, IEC 60947 and BS5486 or equivalentstandards.

The switchgear shall be a type-tested assembly in accordance with IEC

60439-1.

The incoming feeders to the main distributions and outgoing feeders to sub-

distributions are to be equipped with motor-driven circuit breakers equal or

larger than 630A. All remaining outgoing feeders to the rectifiers and

inverters etc. shall be equipped with load break switches and fuses.

The copper busbars shall be equipped with an adequate number of earthing

studs.

B7.3.3.2 Switchgear components

The switchgear installations shall comprise at least:

Steel-clad switchgear cubicles, bulkheaded design, the variouscomponents are separated from one another.

Single copper busbar system.

Busbar earthing studs including earthing fittings.

Cable paralleling arrangements with auxiliary busbar systems,connecting bars for all incoming and outgoing feeders which require

more than two parallel cables.


26/53

B7-23

Fireproof enclosures to the base of the switchgear panels for sealing theoutgoing power cables.

Automatic change over system for the main and sub-distributions.

The switchgear cubicles shall be fitted with the following main items of

equipment:

Plug-in units with circuit breakers, load break switches and motorcontactors, including all necessary monitoring, measuring and controlequipment.

Shutters on the fixed part of the cubicles which prevent accidentalcontact with busbars or outgoing contacts when the plug-in unit is not in

the connected position

Busbars safeguarded against accidental contact.

Current transformers either fixed in the infeed panels or mounted on theplug-in unit.

Relay recess with the protection and monitoring relays, the completeterminal strips, etc. in the infeed panel.

Cable connection compartment with the necessary cable connectingfittings safe against accidental contact.

Plug-in unitsThe switchgear shall be supplied with plug-in units which shall be equipped

essentially with the following units:

Circuit breaker plug-in units with motor-driven stored-energy mechanismwith auxiliary relays, plug-and-socket control connections, electronic

protection relays, mini circuit breaker for monitoring and protection, and

possibly current transformers, etc. Motor plug-in units either with fuses and hand-operated load-break

switch or with motor protection switch, motor contactor, auxiliary relays,

coupling relays, plug-and-socket control connections, bimetallic trip,

control voltage mini circuit breaker, etc.

For feeders of 150 kW and more only circuit breakers shall be used.

Position indications, signals, and the designation plate shall beaccommodated on the front panels of the plug-in units.

Plug-in units with hand operated load-break switches and line-side fuses.The hand operated drive for the load-break switches shall be arranged on

the front panels of the plug-in units.

Withdrawal or engagement of the plug-in units must only be possible withthe power circuit open. To meet this requirement a mechanical/electrical

interlocking shall be provided for each plug-in unit.

Each plug-in unit shall be equipped with a defined operating, test and

inspection position. In the test position the power contacts must be

separated, so that safe testing of the remote and local control system is

ensured. In the inspection position the control circuits must also be

interrupted.


27/53

B7-24

Current transformersThe thermal withstand capability of the instrument transformers shall be

based on a disconnection time of min. 0.5 sec. in the outgoing feeders to

consumers and min. 1.0 sec. in the infeeds.

Accuracy for measurement class 1.0 M 5Accuracy for protection class 10 P 10

Cast-resin insulated, corona-free transformers shall be used. The current

transformers must withstand the dynamic and thermal short-circuit stresses.

Separate cores for protection and measurement shall be provided.

Current transformer terminals must be equipped with short-circuiting links.

Protection relay designThe relays shall be arranged for panel installation behind the doors or

windows of the individual plug-in units or integrated in the circuit breaker.Indicating devices shall be provided which enable it to be seen when a relay

has operated without the need to open the door.

Each circuit breaker shall be equipped with a three-phase, overcurrent time

relay with continuously variable short-circuit trip.

All protection relays have to be selective. The Contractor may offer

additional protection devices if he sees them necessary.

Mimic diagram and local indicationsOn the front of the switchgear cubicle of each main distribution infeed a

colored mimic diagram shall be provided, with the necessary switch position indicators, symbols and signal lamps, containing at least the

following items:

Infeed busbar

Infeed switch position

Infeed earthing switch with position indicator

Transformer symbol

0.40 kV switch position indicator together with the necessary actuatingelements

0.40 kV busbar.

Each plug-in unit shall be equipped with individual signal lamps or position

indicators, which show the following switching conditions locally:

Switch unit of plug-in unit ON/OFF

Plug-in unit not available (not engaged/test)

Plug-in unit OFF - due to fault.

Indication of test, service, isolated, tripped by protection, earthed.

Each infeed panel of the switchgears


28/53

B7-25

No control voltage.

For each circuit breaker

Breaker operations counter.

Control of the circuit breakersThe control of the circuit breakers shall be effected with 220V DC.

It must be possible for each circuit breaker to be operated locally by means

of pushbuttons CLOSE and OPEN.

If the control voltage fails, EMERGENCY-OPEN actuation of the switches

must be possible.

An anti-reclosing device that can only be overridden at the switchgear

cabinet itself shall be provided. It shall be activated when the circuit breakeris tripped by its protection relay.

In each circuit breaker plug-in unit mini circuit breakers shall be provided

for:

Local controls and interlocks

Local signals and fault indications

Local power supply to motor-driven stored energy mechanism.

Tripping of the mini circuit breakers shall be indicated locally.

The circuit breakers of the switchgear installations shall be remotely

controlled from the central control room through the DCS. Appropriate load

transfer features shall be provided between the infeeds/bus couplers.

Control of the Motor Plug-in UnitsThe control of the motor plug-in units shall be effected with 230 V AC.

The control voltage is made by suitable transformers 380/240 V for each

half-bar of main switchgear and distribution.

The monitored control voltage shall be permanently wired from plug-in unit

to plug-in unit so that in each main switchgear and distribution each half-bar

has a separate control voltage circuit. In each motor plug-in unit the controlvoltage shall be protected by a mini circuit breaker, auxiliary changeover

contacts of these shall be wired for trip indication to the central control

room.

The motor plug-in units are to be remotely controlled from the central

control room. Therefore, two coupling relays (ON/OFF, OPEN/CLOSE)

are to be provided.


29/53

B7-26

The self-holding of the contactors for continuously running motors must be

provided in the plug-in units.

An undervoltage monitoring device for monitoring the busbar voltage

shall be provided in each distribution and each half-bar of the main

switchgear. The response value of the monitoring devices must beadjustable from 50 - 100% voltage, the delay time shall be adjustable from

1 to 15 seconds. This device shall provide necessary input to the DCS

system specified in Section B8 for the defined disconnection from the

automatic control level of all respective low voltage motors in the case of

the failure of the busbar voltage.

The emergency consumers shall be reconnected after the emergency diesel

generator has been started and emergency power is available.

Local measuring instrumentsFor measuring instruments only square flush-mounting types class 1.5

shall be used.

As a minimum requirement the following local measurements shall be

provided:

Three-phase current indication of all infeeds and outgoing feeds(including bus couplers) which are equipped with circuit breakers

Single-phase current indication on the plug-in units with hand operatedload-break switches and line-side HRC fuses for outgoing feeds of 250

A or more and to the rectifiers and the electronic change-over units of

Subsection "DC and safe AC systems and associated equipment"

Single-phase current indication on the plug-in units for motors equal to

or greater than 75 kW Voltage indication with suitable 4-way voltmeter selector for

measurement of phase L1 - N, phase L2 - N, and on each busbar phase

L3 - N, phase L1 - L2 in all infeeds of the switchgear installations

Remote indications and measurementsThe Contractor shall provide the following remote measurements and

signals to the CCR trough DCS.

Indications/signalsFor each remote controlled plug- in unit:

Plug-in unit not available (in test position or withdrawn) Switch unit of plug-in unit ON/OFF, each separate

Plug-in unit faulty

For each main distribution half bar and each subdistribution:

No control voltage (as group signal)

Protection activated (as group signal)

No busbar voltage.


30/53

B7-27

Remote measurements (all measurements single phase):

Current (4...20 mA) in all infeeds and bus couplers equipped with circuitbreakers

Current (4...20 mA) in all feeders equipped with circuit breakers

Voltage (4...20 mA) in all infeeds equipped with circuit breakers and inall infeeds of distributions.

Current (4...20 mA) in all motor plug-in units > 75 kW.

B7.3.4 DC and Safe AC systems and associated equipment

B7.3.4.1 General

The main distributions are to be provided as indoor, steel-enclosed cubiclesand are to be furnished with fix mounted equipment

The rectifiers and inverters are to be arranged in sheet steel cubicles, which

are to be matched to the distribution cubicles in respect of height and other

dimensions.

The rectifiers and inverters shall be designed for operation with natural

cooling. If air-cooling is required, then 2 x 100% air fans with monitoring

and alarm signal must be provided.

Main distributions for 220 V DC shall comprise two busbar sections. A

dedicated 100% rectifier-charger unit shall feed each busbar section. One100% battery shall be provided to be fed by one rectifier unit.

The cubicle groups of DC consumers are supplied from each bar via 2 x

100% cable connections, which are decoupled by diodes in the consumercubicles.

The 230 V, 50Hz safe AC shall comprise a single busbar distribution feeded

by a 1 x 100% inverter equipped with static bypass switch and a manual

bypass switch.

The outgoing circuits in the safe AC main distributions are to be equipped

with fuse- and load-break switches, fuses and contactors, mini-circuitbreakers, etc.

The individual cubicles are to be bulkheaded against one another by sheetmetal walls or equivalent material.


31/53

B7-28

B7.3.4.2 Switchgear (DC, safe AC)

The 220 V DC switchgear and the 230 V Safe AC switchgear shall be

designed as indoor switchgear of sheet-steel-clad type however with fixed

installed equipment.

The infeed switches of the main distributions are to be provided as load

breaker switches. The infeeds from the battery are to be taken via isolating

fuses (fuses shall be monitored).

All outgoing feeders from the main switchgear distribution to consumers are

to be equipped with monitored fuses and hand-operated load-break switches

or with MCBs with auxiliary contacts, unless remote control is required,

where in this case, motor-operated circuit breakers shall be provided.

A voltmeter, an undervoltage relay and an overvoltage relay shall be

provided for each busbar.

The 220 V DC systems shall each be equipped with an earth fault and

insulation monitoring device.

The cable connections between rectifiers and/or batteries and/or busbars are

to be carried out with single-conductor cables.

Mimic diagram and local indicationsColored mimic diagrams are to be provided in each case on the front of the

infeed cubicles with the necessary switch position indications, device

symbols and alarm lamps.

The mimic diagram for the DC systems has to contain at least the following:

0.40 kV busbar of the main switchgear with position indication for theload break switch for the rectifier supply

Symbols for rectifier and battery

Infeed circuit breakers with position indication and the necessaryoperating elements

DC main distribution busbar.

The mimic diagram for the safe AC system has to contain at least the

following:

0.38 kV switchgear with position indication for the 0.40 kV loadbreak switch

220 V DC main distribution with position indication for the outgoingload break switch for the inverter

Inverter and change-over device symbols with ON-OFF positionindication in each case and the necessary operating elements

Safe AC distribution

Frequency indicator.


32/53

B7-29

Control signalization and position indication of the direct current and safe

AC installation is to be provided also in the central control room through the

DCS.

Each unit shall be equipped with individual signal lamps and position

indications that show the following switching conditions locally:

Switch unit ON/OFF

Unit not available (not engaged/test)

Unit OFF - due to fault.

The following signals shall be additionally provided in the infeed panels of

the switchgear:

No control voltage 220 V DC

No busbar voltage

Ground fault (for the 220 V DC system only).

Circuit breakers shall be equipped with operation counters.

Control and signalizationThe control of the circuit breakers and motor units shall be carried out as

described in clause "Low Voltage AC Switchgear".

Local auxiliary relays and measuring instrumentsAll infeeds to DC switchgears shall be equipped with ammeters.

For the rectifiers and inverters, the incoming and outgoing currents and

voltages are to be indicated separately. The busbar voltages of the main220 V DC distributions are also to be indicated.

The current and voltage measurements for the 230 V Safe AC is

to be executed in the same way as for the 0.38 kV distributions in Section

"Low Voltage AC Switchgear".

Remote indications and measurements

The remote indications of the circuit breakers and motor unit shall be

carried out as described in Section "Low Voltage AC Switchgear".

The minimum scope of measurement transducers for measurement in the

central control room are:

Battery current and voltage

Current measuring transducers for all infeeds

Voltage measuring transducers for each half busbar voltage.


33/53

B7-30

B7.3.4.3 Battery charging equipment

Each battery charger must be suitable for the charging and floating of the

nickel-cadmium battery and for supplying of all the DC consumers and the

inverters for the 230 V Safe AC system at the same time. Above

requirements shall also be applicable if the battery was drained prior to startof charging.

The rectifiers are to be provided as thyristor controlled devices with current-

voltage characteristic for stand-by parallel operation with the associated

batteries.

The following technical features and monitoring equipment is to be

provided for the individual battery chargers:

Radio interference suppression of the battery chargers according to theappropriate IEC regulations

Monitoring the charging circuit for interruption Voltage monitoring of the incoming three-phase supply, with an

overvoltage of + 15% and an undervoltage of - 15%, automatic

disconnection of the battery charger must occur

Voltage monitoring of the DC output, with an overvoltage of + 15%,automatic disconnection of the battery charger must occur.

All cases of disconnection must be indicated as a fault alarm in the front

door of the unit.

The local fault alarms and disconnections are to be combined as a common

alarm - rectifier fault - to the central control room (DCS).

The battery chargers are to be equipped with high rate charging stages that

can be set at 1.7 V/cell between 1 to 6 hours after input failure.

On the front of the rectifier cubicles, the Contractor has to provide all the

necessary monitoring equipment, measuring instruments, other devices,

switches, indicator lamps and corresponding fixings for the cables.

Alternatively the Contractor may offer an integrated numeric control device

(visible during normal operation through inspection window in front door),

which combines all functions.

B7.3.4.4 Batteries

For the DC Systems, the Contractor shall supply batteries of the Ni Cd

type.

Battery main fuses in a separate fuse box to be provided. The battery fuses

shall be monitored.


34/53

B7-31

The intercell connections shall be fully insulated. Welded intercell

connections are not permitted.

The batteries are to be mounted on insulated subframes with the necessary

consoles and fixing material.

Each battery shall have the capacity to supply the load for a period of at

least one (1) hour.

B7.3.4.5 Inverter with electronic change-over equipment

In order to be able to maintain an uninterruptable supply in the event of grid

and generating failure, an inverter with automatic static bypass -over

equipment and manual bypass switch/facility is to be provided.

The static inverter must be suitable for 100% of the power requirement.

The following features and monitoring equipment is to be provided for the

AC inverter:

Radio interference suppression according to the appropriate IECpublications

DC undervoltage monitoring

AC overvoltage monitoring

AC undervoltage monitoring.

On activation of the above devices, switch-over to power supply from the

AC bus shall occur; the fault is to be individually indicated locally.

The local fault alarms are to be combined as a common alarm - inverter

fault - to the central control room (DCS).

The inverter is to be protected on the input and output sides and is to be

equipped with the necessary isolating points. It must be possible to block

the inverter on the input side in the case of high rate battery charging or they

must be so designed that no damage will occur during this phase of

charging.

In case of operation in bypass mode backfeeding into the 220V DC system

shall not be possible.

On the front of the inverter cubicles, the Contractor has to provide all the

necessary monitoring equipment, measuring instruments, other devices,

switches, indicator lamps and corresponding fixings for the cables.

Alternatively the Contractor may offer an integrated numeric control device

(visible during normal operation through inspection window in front door),

which combines all functions.


35/53

B7-32

In the case of a short circuit at a consumer on the safe busbar, the voltage

tolerances shall not be exceeded.

Sizing of fuses and inverter output in case of short circuits shall be properly

coordinated and shall be fully selective under all operating conditions.

A static bypass switch is to be provided and shall enable automatic,

uninterrupted, synchronous switchover to the consumer busbar in the event

of total inverter failure or high voltage dip on the safe busbar.

Automatic and manual activation of the static bypass switch shall be

possible.

The change-over device provided shall be equipped with thyristor switches,

control electronics and a check-out system. The checkout system must make

it possible to test the correct functioning of the unit without disturbing the

operation of the consumers.

B7.3.4.6 DC/DC Converters (if applicable)

I&C cabinets and other consumers requiring 24 V DC supply will be

supplied from the 220 V DC system via 220 V/26 V DC/DC converters.

Each 26 V consumer will be supplied from 2 x 100% DC/DC converters

that are decoupled by diodes in the consumer cubicles. In case of a failure of

one of the converters, the remaining one shall be capable of supplying the

complete load without interruption and within the required voltagetolerances.

The DC/DC converters shall be of modular design and shall be integrated

into sheet steel cabinets.

Local indicatorsThe following indications shall be provided locally:

Input fuse monitoring (for each DC/DC converter)

Undervoltage input

Undervoltage/overvoltage output

Output current and output voltage Overload

Signalization of fault signals shall also be provided at the central control

room (DCS).


36/53

B7-33

B7.3.5 Emergency AC power supply system

GeneralAn emergency power supply shall be provided by emergency diesel

generator(s) as a complete package, which shall supply AC power to all

essential consumers of the plant in case of a blackout. After a definedvoltage drop of the 0.40 kV common auxiliary busbar the diesel generator(s)

shall cut in automatically and shall supply all essential loads so that the

required controlled shut down procedure of the plant can be carried out

without damaging any of the plant equipment.

In case of a complete blackout of the auxiliary power supply, the emergency

diesel generator set shall be sufficient to meet the electrical demand of:

All consumers connected to the 0.40 kV "essential" distribution boardsrequired for safe shutdown of the plant

Additionally 20% safety margin.

The diesel generators shall preferably be supplied in a container, fully

installed, workshop tested and ready for operation.

B7.3.5.1 Diesel engine and auxiliaries

GeneralThe engine shall be water-cooled, with a closed circuit radiator and fan and

shall be equipped with an exhaust gas turbo-charger for indoor installation.

LFO shall be the common fuel.

A suitable electrical heating of the cooling water during standstill of thediesel generator set shall be provided to allow for the specified starting time.

Electrical motor and battery with charger shall start the diesel engine. The

capacity of the battery shall be such as to ensure three consecutive starts of

the diesel engine within 10 minutes.

The diesel engine shall be directly coupled to the generator and both

installed together on a common base frame. Vibration absorbers shall be

used to prevent transmission of vibrations to the surrounding area.

Lubrication system

The engine and the generator shall be fully pressure-lubricated. The main oilpump shall be gear-driven from the main shaft. Where necessary, a suitable

periodic lubrication equipment shall be provided to keep the engine in

readiness to start at any time.

Fuel supply and injection systemAn integrated fuel meter shall be installed, suitably connected to the fuel

admission and return system, to measure the actual consumption of the

engine.


37/53

B7-34

For the supply of the diesel engine with fuel the Contractor shall provide a

daily tank of adequate capacity (only if required) and refilling from the LFO

common tank.

The Contractor shall provide all necessary means such as pumps, pipes,

filters etc. to accomplish the filling of the daily tank from the LFO commontank.

The daily tank shall be fitted with visual level indicator and level alarm

devices for remote indication.

The suction of the extraction line shall be arranged at least 10 cm above the

daily tank bottom or otherwise suitably positioned in order not to take in

sludge or water which may have accumulated. Furthermore, a flame trap

shall protect the ventilation openings of the tank.

Air intake and exhaust system

The engine shall be fitted with an outdoor installed oil wetted air filter.

Temperature-resistant materials shall be used for the exhaust piping and the

required expansion bellows. Exhaust silencers shall be galvanized.

Expansion joints in the exhaust pipe shall be made of metal.

Flexible connections to the air intake duct, exhaust line and all other

external pipework shall be provided.

B7.3.5.2 Control and monitoring equipment

The engine shall be equipped with all necessary local switches and controlequipment for starting, stopping and speed variations etc.

Start-up and shutdown of the set shall be possible from the local control

board and from the central control room through the DCS.

The set shall start-up automatically to the required load when the normal

busbar voltage (400 V AC) fails.

Only overspeed sensing element and shutdown mechanism separate from

the regular governor apparatus and governor drive shall be accepted. The

overspeed trip shall act on the injection pump independent of the governor

link and shall remain operative even if the governor would accidentally bedisconnected.

The following control, indication and alarm equipment shall be provided as

a minimum on the local control board:

Level indication of the fuel tank with alarm at 20%

Pressure indication of the lube oil with low pressure alarm and tripsignals

Temperature indication of the bearings with high temperature alarm


38/53

B7-35

Temperature alarms of the generator winding

Emergency diesel generating set in operation (indication)

Generator overload alarm

Operating hour meter and start-up counter

Speed indication with alarm and trip signals

Generator voltage, current, frequency, active and reactive powerindication

Automatic synchronizing equipment

Manual synchronizing equipment such as double voltmeter, doublefrequency meter, synchronoscope, etc.

Manual/automatic synchronizing selector switch

Start/stop push buttons

Manual/automatic voltage regulator selector switch

Switches for manual adjustment of generator voltage

Generator circuit breaker ON/OFF control switch and indication

Generator protection relays activation (individual alarm and trip signals

per each protection relay) Other alarm and trip signals.

Alarms shall be annunciated individually on the local annunciator unit on

the local control board and remotely in the central control room as a group

alarms.

After starting of the emergency diesel generator the emergency consumers

shall be connected to their switchgears in groups by the DCS.

B7.3.5.3 Diesel Generator

The generator shall be air-cooled with forced ventilation and shall comply

with IEC 60034.

A heater shall be provided to protect the generator against humidity during

stand-still (automatically initiated when the set is being out of service).

The generator winding insulation shall be according to class F. The

temperature rise, however, at rated load shall not exceed the figures for class

B insulation.

Six Pt 100 temperature sensors shall be provided within the stator windings,

wired to terminal boxes.

The generator shall tolerate the sudden application or rejection of 50% of its

rated power without unacceptably high voltage fluctuations in excess of

5%.

A static or brushless rotating diode rectifier excitation system shall be

provided. The rotating diodes shall be easily accessible for maintenance.


39/53

B7-36

A solid state type voltage regulator with automatic and manual control to

control the set within a deviation of 0.5% from no-load to full load at

rated frequency, shall be provided.

The diesel generator set shall be equipped with automatic synchronizing

device for parallel operation with the grid. This is for testing the enginefrom time to time in the load condition and for switch-over to the normal

grid after an emergency operation of the diesel generator sets.

The protection relays of the digital type, as indicated below, shall be

regarded as the minimum scope, but shall not be limited to the following:

Voltage controlled inverse time overcurrent protection

Reverse power protection Overvoltage protection

Overtemperature protection (stator windings)

Overcurrent protection

Overload protection.

B7.3.6 Cables and cable supporting structures

B7.3.6.1 Cables

The detailed requirements for power, control and measuring cable detailed

in Section B0 "General Technical Requirements" are to be regarded as basic

reference for this specification.

In addition, direct buried cables shall be of armoured type.

As much as possible, cables should be laid in overhead trays and in

exclusive structures, not along with pipes.

The cables shall be manufactured in accordance with IEC Standards, shall

be reliable and maintenance free.

B7.3.6.2 Cable supporting structures

The requirements for cable trays, cable risers, hanger rods, screws, clamps

and all fixing material, etc, detailed in Section B0 "General Technical

Requirements" are to be regarded as basic reference for this specification.


40/53

B7-37

B7.3.6.3 Terminal boxes and local control boxes

The requirements for local control and level control cabinets or boxes,

terminal boxes and cabinets are detailed in Section B0 "General Technical

Requirements" are to be regarded as basic reference for this specification.

B7.3.7 Lighting and small power installations

B7.3.7.1 Lighting system

GeneralFor protection against contact with live components, all lighting fixtures

must be suitable for the following protection measures:

Protective conductor connection, or Protective insulationAnd must visibly carry the accepted symbol to indicate this.

In plant areas subject to danger of explosion the necessary explosion-proof

lighting fittings, cable connection boxes and pushbuttons are to be used.

The external and internal lighting is to be designed so that the lighting

illumination intensities as stated in the data sheets "Performance and Design

Data" shall be achieved.

The lighting intensities stipulated shall be verified both by calculation and

measurement.

Lighting subdistribution unitsMetal-clad or plastic-clad subdistribution units suitable for flush or surface

mounting on the walls are to be provided. Each lighting subdistribution unit

must at least be equipped with:

Manual feed-in change-over switches with I - 0 - II positions

One ammeter in the feed-in system

One voltmeter with 4-way change-over switch for measurementsbetween the individual phases and the neutral conductor and between two

phases to detect the busbar voltage 5 busbars for 3-phase system, neutral and earth

The necessary MCBs for lighting circuits and control

The necessary MCBs for domestic power outlets (sockets)

The necessary current relays and contactors for pushbutton energizing,de-energizing of lighting circuits

The necessary daylight-controlled switching circuits for automaticcontrol of external lighting circuits in open-air installations and housed

areas exposed to direct daylight. The adjusting range of the daylight-

controlled switching circuits must be from 2 to 100 Lux.


41/53

B7-38

For indoor and outdoor lighting and for the emergency lighting separate

lighting distribution units shall be provided (i.e. separation of power

sources).

The lighting subdistribution units are to be designed so that after handingover a complete 20 per cent spare space is still available.

External lightingCables with a cross-section of at least 2.5 mm are to be laid as lighting

cable for fluorescent lamps.

The lights must be connected in a 3-phase circuit, so that in the event of

failure of one phase only each third lamp will fail. A 5-core power copper

cable with a minimum cross-section of 6 mm is to be laid as lighting cable

for metal-vapor lamps.

Control of external lighting shall be effected automatically with daylight-controlled switching circuits. For each lighting subdistribution unit of

external lighting purposes there must be provided one separate daylight-

controlled switching circuit.

The street lighting fittings are to be installed as totally enclosed anti-glare

column-top luminaries cut-off type angled at 15 to the horizontal with a

light source height and a light source spacing according to the required

minimum lighting intensity.

The housing of the lighting fitting, which is subdivided into a lamp

compartment and an auxiliary gear compartment, shall be fitted with

metal-vapor lamps of ellipsoidal or tubular shape.

The electrical components housed in the auxiliary gear compartment, such

as p.f. correction capacitors, stabilizing impedance, starter and suppressorsare to be mounted jointly on an insulating board capable of being swung

out, fixed in position and removed for maintenance purposes. Each lighting

column must contain the necessary internal wiring (3 x 2.5 mm copper,

PVC) from each lighting fitting on the top of the lighting column to the

connection compartment above the ground.

For safety reasons the lamp housing shall be provided with a door switch to

disconnect the starter voltage on opening the fitting.

The p.f. correction equipment of the lighting fitting must achieve a powerfactor of no less than 0.9.

Suitable starters are to be provided for the halogen lamps, so that hot lamps

can be restarted immediately or at any time during the cooling stage.


42/53

B7-39

The specular reflectors mounted in the lamp compartment shall be provided

with facilities for adjusting the focusing of the lamp in two perpendicular

axes.

For the external lighting installation, one-piece steel columns with

continuous taper and welded-on steel mounting plate are to be used.

The corrosion protection of the lighting columns shall be executed by hot-

dip galvanizing on the inner and outer faces.

The lighting columns are to be provided with the following equipment as

the minimum:

Cable entry hole in the flange plate

Cable connection compartment above ground, with welded-on mountingbar including fixing screws for attachment of the lighting column boxes

Lighting column connection boxes. These are to be made of

thermoplastic material with transparent cover, fitted with fuse base andfuse, also connecting terminals for low voltage cables to a maximum of

three cables each 4 x 6 mm, including cable glands

PVC copper cable 3 x 2.5 mm between the lighting column connectionboxes and each lighting fitting

Earthing screws with suitable bimetallic feature are to be provided forattaching the lead-coated copper conductor of the earthing system

Column top lighting fittings (one, two or four lighting fittings on onelighting column according to the requirements) with halogen lamp.

Suitable column foundations are to be provided.

Aircraft warning lightsAircraft warning lights shall be in accordance with ICAO and local

regulations.

Internal lightingFor rooms, either in the power station or surrounding buildings, where a

headroom o

b7 electrical works

Documents