Design basis Report

Project: 印度 TIRODA（提隆达）3×660MW 燃煤电站

TIRODA THERMAL POWER PROJECT 1980 MW (2x660 MW Phase - I+1x660MW Phase-II)

Tiroda, Gondia District, Maharashtra Owner: ADANI POWER MAHARASHTRA PRIVATE LIMITED TIRODA, MAHARASHTRA Owner’s Consultant :

FICHTNER Consulting Engineers (India) Private Limited and BLACK & VEATCH

Vendor:

SICHUAN MACHINERY & EQUIPMENT IMP. & EXP. CO., LTD

西南电力设计院 SOUTHWEST ELECTRIC POWER DESIGN INSTITUTE

APMPL DOC.NO. Revision TIR1-CBE-OTH-BE-X-001 0

PROJECT DOC. TITLE :

DESIGN BASIS REPORT FOR ELECTRICAL PART DOC. NO.:

50-F303C-D01-01 Revision 0 APPROVAL STATUS :

1 2009.04 REVISDE AS PER APML'S COMMENTS

0 2008.11 FIRST REVISION

INITIALS SIGN INITIALS SIGN INITIALS SIGN DETAILS OF REVISION REV DATE

PREPARED CHECKED APPROVED

2

CONTENTS

CLAUSE NO. DESCRIPTION PAGE No

1 GENERAL DESCRIPTION········································································································································· 5

1.1 INTENT OF DESIGN BASIC REPORT················································································································· 5

1.2 SCOPE OF DESIGN················································································································································ 5

1.3 DESIGN PHILOSOPHY ·········································································································································· 5

2 ELECTIC CONNECTION··········································································································································· 6

2.1 SLD FOR MAIN CONNECTION····························································································································· 6

2.2 SLD FOR HV-LV AUXILIARY POWER SYSTEM ······························································································ 7

3 SHORT CIRCUIT CURRENT CALCULATION AND EQUIPMENT ELECTION············································ 12

3.1 RESULT OF SHORT CIRCUIT CURRENT CALCULATION ········································································· 12

3.2 PARAMETERS OF MAIN EQUIPMENT ············································································································ 13

4 GENERATOR AND EXCITATION ·························································································································· 19

4.1 TYPE OF GENERATOR ········································································································································ 19

4.2 RATING····································································································································································· 19

4.3 DESIGN CRITERIA ················································································································································ 20

4.4 EXCITATION SYSTEM ········································································································································· 20

5 DESCRIPTION OF ELECTRIC EQUIPMENT LAYOUT··················································································· 21

5.1 LAYOUT OF GENERATOR OUTPUT SYSTEM ······························································································ 21

5.2 LAYOUT OF GT UT & ST ····································································································································· 21

5.3 LAYOUT OF 400KV SWITCHYARD ·················································································································· 21

5.4 LAYOUT OF 220KV SWITCHYARD··················································································································· 22

5.5 LAYOUT OF HV/LV SWITCHGEAR ··················································································································· 22

6 DC SYSTEM & UPS··················································································································································· 23

6.1 DC SYSTEM···························································································································································· 23

6.2 UPS ·········································································································································································· 24

7 ELECTRICAL PROTECTION & CONTROL & AUTOMECHANISM ······························································· 25

3

7.1 PROTECTION·························································································································································· 25

7.2 400KV & 220KV SWITCHYARD COMPUTERIZED MONITORING AND CONTROL SYSTEM··············· 30

7.3 CONTROL AND INSTRUMENTATION··············································································································· 31

7.4 CONTROL SYSTEM OF AUXILIARY WORKSHOP·························································································· 32

7.5 CHANGE-OVER MODE········································································································································· 33

7.6 UNIT FAULT WAVE RECORDER ······················································································································· 33

8 LIGHTNING PROTECTION & EARTHING SYSTEM ························································································ 33

8.1 LIGHTNING PROTECTION SYSTEM ················································································································ 33

8.2 EARTHING SYSTEM ············································································································································· 34

9 LIGHTING AND MAINTENANCE SYSTEM ········································································································· 34

9.1 POWER SUPPLY SYSTEM ·································································································································· 34

9.2 CONTROL OF THE LIGHTING SYSTEM ·········································································································· 36

9.3 LIGHTING DISTRIBUTION BOX ························································································································· 36

9.4 CABLE, WIRE·························································································································································· 37

9.5 RACEWAY ······························································································································································· 37

10 CABLES & CABLING ············································································································································· 37

10.1 CABLES ································································································································································· 37

10.2 CABLING································································································································································ 38

4

ANNEXURE

ANNEXURE I

SIZING CALCULATION FOR GENERATOR NEUTRAL GROUNDING SYSTEM ANNEXURE II

SIZING CALCULATION FOR IPB&SPB ANNEXURE III SHORT CIRCUIT CURRENT CALCULATION ANNEXURE IV

CALCULATION FOR CT SELECTION ANNEXURE V

CALCULATION FOR PT SELECTION ANNEXURE VI

CALCULATION FOR UNIT 220V BATTERY AND CHARGER ANNEXURE VII

CALCULATION FOR UNIT AND COMMON AC UPS SYSTEM ANNEXURE VIII

MCC LOADS CALCULATION

5

1 General Description 1.1 Intent Of Design Basic Report

In this design basis report, the design criteria and principle of electrical system and

equipment of the plant, the equipment main parameters, control & operation philosophy,

metering & protection shall be described.

1.2 Scope of Design

The scope of this design includes all electrical system of the plant. The interface between

the power plant and the transmission line shall be defined at the clamp of outgoing feeder

mast inside power plant.

1.3 Design Philosophy

1.3.1 Basis of design

The contract between SCMEC and APMPL.

The contract between SCMEC/APMPL and manufacturer of generator.

The contract between SCMEC and SWEPDI.

All minutes of meeting for electrical up to now.

1.3.2 Code & Standard

Electrical equipment and system for this project shall be designed, constructed, tested

and installed in accordance with the latest editions of GB standards.

Indian Electricity Rules & Acts and Applicable Indian standards shall be also considered

as well.

It shall be as per IEC standard and as per the contract specification.

1.3.3 Environmental condition

The equipment shall be capable of continuous full load operation under the following

conditions:(based on “Basic design technical requirement lists for TIRODA project (Input

from APMPL)”)

(1) Air temperature Units Value Design ambient air temperature: ℃ 50 (2) Relative humidity Design humidity: % 95 (3) Wind speed Average monthly highest: km/hr 5.9

6

Average monthly lowest: km/hr 1.6 Basic wind speed: m/sec 47 (4) Rainfall 24 Hours Max： mm 395 Hourly Max： mm 150 15 Min： mm 100 (5) Seismic Zone (As per IS: 1893) II (6) Plant elevation: (above flood leve) m 292

1.3.4 Electrical design condition

(1) Voltage Levels

Following voltage levels shall be adopted for power station auxiliary motors.

Consumer Voltage Levels Fault level

P>2000 KW 11 kV

160 kW< P≤2000 kW 6.6 kV 40kA/3s

0.2kW<P≤160 kW

415 V

50kA/1s

AC

P≤0.2 kW 240V

DC 220V 25kA/1s

(2) Range Of Variation

Voltage Variation :+_ 5%

Frequency Variation :47.5Hz to 51.5Hz

Combined Voltage and frequency Variation : 10% (Absolute sum)

220V DC system voltage variations shall be limited for -15% (187V) to +10% (242V)

2 Electic connection 2.1 SLD For Main Connection

2.1.1 Capacity of this plant

For phase-I of this project 3 nos. of 660MW T-G unit shall be build up , and 2 nos. shall

be more for phase-II.

7

2.1.2 Outputing of generator

For phase-I 3 sets of 660MW T-G unit shall be separately connected to 400kV switchyard

(inside power plant) with generator-transformer unit connection mode. Generator circuit-

breaker shall not be adopted.

2.1.3 Start-up power

Power for Unit final commissioning is envisaged from 400 kV Switchyard only through

Station Transformer. Startup power from 220 kV switchyard shall be used for pre-

commissioning activities of the plant auxiliries, till 400 kV Switchyard is charged. Rating

of this transformer is proposed as 31.5 MVA.

2.1.4 400kV switchyard

Power generated at the plant shall be evacuated at 400kV level. And the 400kV

switchyard(inside power plant) shall adopt 1&1/2 breaker configuration. 3 nos. G-T unit

and 3 nos. station transformer shall be connected to the 400kV switchyard. Due to the

nos. of 400kV outgoing lines shall be 4,at the same time,bus reactor & bus equipment

shall be adopted. So 400kV switchyard total no.of bays shall be 12.(4 numbers outgoing

lines, 3 GTs, 3 STs, 2 Bus reactors along with Bus CVTs)

400kV main bus of phase-I shall have capability to connect with phase-II by switch.

2.1.5 Type of generator transformer & switchyard equipment

(1) The generator transformers of this plant shall be single-phase type, and a spare

phase of generator transformer shall be set .

(2) Both 400kV & 220kV switchyard shall adopt outdoor type equipments.

2.1.6 Type of equipments earthing

400kV system : solid grounded.

220kV system: solid grounded.

2.2 SLD For HV-LV Auxiliary power system

2.2.1 HV auxiliary power system

2.2.1.1 General

The HV Power System shall supply power to HV auxiliary loads of the plant and 2 voltage

levels i.e. 11kV(3phase 3 wire,motor above 2 MW & transformers),6.6kV(3phase 3 wire,

motor above 200 kW and upto 2000 kW) shall be adopted for HV auxiliary power system.

The 11kV motor loads,11kV / 6.6kV unit/station auxiliary transformers and 11kV /

0.415kV service transformers shall be fed from 11kV switchgears. The 6.6 kV motor

8

loads shall be fed from 6.6 kV switchgears.

HV auxiliary power system shall be grounded through resistor and earth fault current for

NGR for 11 kV and 6.6 kV system shall be limited to 400Amps.

2.2.1.2 Description

For each 660MW unit there shall be 2 nos. unit transformer (22/11.5kV,double-winding)

rated 35MVA,which derive power from the corresponding generator outlet terminal

through IPBD,and 1 no station transformer (22/11.5-11.5kV,split-winding) rated 80/40-

40MVA,which derives power from 400kV switchyard.

The 11kV unit switchgears and the 11kV station switchgears shall be fed from the Unit

Transformers (UTs) and Station Transformers (STs) respectively. 2 nos. 11kV unit

section(section-A,section-B) and 2 nos. 11kV station section(section-A,section-B) shall

be set for each 660MW unit. 11kV unit section shall supply power for unit loads i.e.

ESP,turbine and boiler loads,and 11kV station section shall supply power for station

loads i.e. coal handling,ash handling,water supply system ect. Tie feeders shall be

provided between station switchgear and unit switchgear so that during non availability of

one unit transformer, the station transformer shall feed the loads connected to the

respective unit bus. Automatic fast changeover scheme for changeover of supply from

Unit switchgear to station switchgear in the event of UT outage shall be provided.

There also shall be 2 nos. unit auxiliaries transformer(11/6.6kV,double-winding) rated

16MVA for each 660MW uint,and 2 nos. station auxiliaries transformer(11/6.6kV,double-

winding) rated 5MVAfor the plant. The 6.6kV unit switchgears and the 6.6kV station

switchgears shall be fed from the uint auxiliaries transformers (UATs) and the station

auxiliaries transformers (SATs) respectively. There shall be 2 nos. 6.6kV unit

section(section-A,section-B) for each 660MW unit and 2 nos. 6.6kV station

section(section-1A,section-1B) for the plant.

1 no. start-up transformer (220/11.5kV,double-winding) rated 31.5MVA shall be set for

the plant ,which derives power form 220kV switchyard. The 11kV start-up switchgears

shall be fed from start-up transformer. 11 kV startup Switchgear shall have one bus

section only. Startup switchgear shall be connected to Station Switchboard 1A/1B of Unit-

1 only.

For 11 kV system, segregated phase busduct shall be uesed. For 6.6 kV system,

busducts shall be not envisaged,cables shall be used.

9

One motor and one transformer type spare feeder shall be provided (Highest size of

motor and transformer) on each 11kV/6.6kV bus section.

2.2.2 LV auxiliary power system

2.2.2.1 General

For feeding the 415/240V AC loads of the plant, LV switchgear power control

centers(PCCs) and motor control centres (MCCs) shall be provided. The switchboard

shall derive power from the designated service transformers.

The LV auxiliary power system shall be composed by AC power supply system and

emergency power system.

The LV auxiliary power system shall be grounded directly.

2.2.2.2 AC power supply system description

LV service transformers,supplied power to 415/240V system,shall derive power from

11kV unit/station bus sections. 2x100% rated Service transformers shall be provided for

each auxiliary system,each transformer shall be connected to PCC bus section through

a incomer breaker. Each PCC bus shall be devided to two sections and the two sections

shall be connected together through a bus coupler breaker. The incomer and bus coupler

breakers shall make it possible for a switchgear bus section to be fed from two separate

sources with auto & manual live changeover facilities.

Normally each section of PCC bus shall be fed by its own incomer and the bus coupler

breaker shall be open. In case of the incomer failed, under-voltage actuated changeover

facility shall work, the other source shall take place by tripping of failed incomer and

closing of bus coupler breaker. After restoration of normal supply, the incomer breaker

shall be closed, and the bus bus coupler breaker shall be either automatically or

manually tripped. The LV service transformer shall distribute power through feeder

breakers to motors rated 75 kW and above,and to motor control centers (MCC).

LV PCCs shall be used to feed balanced 3-ph,4-wire, 415V non-motor loads and MCCs

shall be used to feed balanced 3-ph, 415V motor loads. 1-Ph, 240V AC loads shall be fed

from ACDB (AC distribution board) or PDBs (power distribution board). ACDBs and

PDBs shall receive power from PCC.

LV transformers located indoor in the Power house building shall be of dry type,and

those located outdoor in the Off site areas such as ESP,CHP, AHP, WTP, CT etc. shall

be of oil filled type.The max. rating shalll be limited to 2500 kVA in order to restrict LV

10

circuit fault level to 50kA(rms). Rating of LV service transformer shall be either

11/0.433kV or 6.6/0.433 V. LV Switchboards shall be rated for 415 V.The transformers

shall have off-load taps of ±2x2.5% on 11/6.6kV side for constant voltage on LV side,in

case HV voltage variation.

1.1 kV class non-segregated phase bus duct shall be provided for connection between all

LV service transformers and their respective 415V switchgears.

2.2.2.3 Emergency power system description

Emergency power system shall be set for the palnt. The function of the emergency power

system is to provide power to facilitate an orderly and safe shutdown of the plant in case

the loss of all unit and station power services. 1 no. diesel generator of suitable rating for

the unit shall be set for each 660MW unit. The rating of such DG sets shall be 1000kW.

In case of non availability of unit DG set ,A standby DG set shall be set.

There shall be two DG set rooms which shall be located at the transformeryard outside

column-A of turbine house.

Each emergency generator consists of one diesel engine and one generator. The diesel

engine shall burn diesel fuel. The emergency generator shall be connected to relative

415/240V emergency switchgear buses,after loss of the auxiliary power sources, the

emergency generator shall supply power to the emergency buses. The standby DG set

shall be interconnected to all 3unit emergency switchgear.

The normal condition of the emergency generator shall be de-energized and in ready

condition.The emergency condition occurs when there is no power available from the unit

auxiliary and station auxiliary transformers. The emergency generator shall run and

supply power to emergency loads.

The emergency generator shalll be periodically tested with the plant in order to confirm its

ready-to-start condition. It shall be manually started, brought up to speed and voltage,

synchronized onto 415/240V bus, and loaded upto the generator nameplate rating.

2.2.3 AC&DC motors

2.2.3.1 General

I) Motors shall be furnished in accordance with both this general specification and the

accompanying driven equipment specification.

II) In case of any discrepancy, the driven equipment specification shall govern.

11

III) The motors shall be installed in hot, humid and tropical atmosphere,highly polluted

with coal dust. Canopy to be provided to all outdoor installed motors.

IV) For motor installed outdoor and exposed to direct sun rays, the effect of solar heat

shall be considered in the determination of the design ambient temperature.

2.2.3.2 Running requirments

I) Motor shall run continuously at rated output over the entire range of voltage and

frequency variations as given in the annexure.

II) The motor shall be capable of operating satisfactorily at full load for 5 minutes without

injurious heating with 75% rated voltage at motor terminals.

2.2.3.3 Starting requirements

I) Motor shall be designed for direct on line starting at full voltage. Starting current shall

not exceed 6 times full load current for all HT auxiliaries, except B.F.P Motor, BFP motors

it shall be 4.5 times only.

II) No further tolerances are applicable on starting current specified above for H.T motors.

III) For LT motor the applicable staring current shall be 6 times full load current subject to

IS tolerance.

IV) The motor shall be capable of withstanding the stresses imposed if started at 110%

rated voltage.

V) Motor shall start with rated load and accelerate to full speed with 80% rated voltage at

motor terminals except BFP motor. In case of BFP motor it shall be 75% rated voltage.

VI) Motor shall be capable of three equally spread starts per hour, two starts in quick

succession from cold condition and one restart from hot condition.

VII) Pump motor subject to reverse rotation shall be designed to withstand the stresses

encountered when starting with shaft rotating at 125% rated speed in reverse direction.

2.2.3.4 Stress during bus transfer

I) The motor may be subjected to sudden application of 150% rated voltage during bus

transfer,due to the phase difference between the incoming voltage and motor residual

voltage.

II) The motor shall be designed to withstand any torsional and/or high current stresses

which may result, without experiencing any deterioration in the normal life and

performance characteristics

2.2.3.5 Locked Rotor Withstand Time

12

I) The locked rotor withstand time under hot condition at 110% rated voltage shall be

more than motor starting time by at least 2.5 seconds for motors upto 20 seconds starting

time and by 5 seconds for motor with more than 20 seconds starting time.

II) Starting time mentioned above is at minimum permissible voltage of 80% rated voltage.

III) Hot thermal withstand curve shall have a margin of at least 10% over the full load

current of the motor to permit relay setting utilizing motor rated capacity.

2.2.3.6 Winding and Insulation

I) All insulated winding shall be of copper.

II) All Motors shall have class F insulation but, limited to class B temperature rise.

III) Windings shall be impregnated to make them non-hygroscopic and oil resistant.

2.2.3.7 Tropical Protection

I) All motors shall have fungus protection involving special treatment of insulation and

metal against fungus, insects and corrosion.

II) All fittingsand hardwares shall be corrosion resistant.

3 Short Circuit Current Calculation And Equipment Election

Short circuit current of this project is calculated by ETAP software.

3.1 Result of short circuit current calculation

Values of the short-circuit point Short-circuit

current point Initial Sym rms (kA) Peak (kA)

400kV main bus 27.4 75

Outlet of Generator 226.5 618.1

LV side of UT-1A(11kV

bus)

36.3 96.6

LV side of UT-1B(11kV

bus)

31.7 84.7

LV side of UAT-1A(6.6kV

bus)

23.7 61.9

LV side of UAT-1B(6.6kV

bus)

24.4 63.7

LV side of ST-1(11kV bus) 30 77.3

13

LV side of SAT-

1A/1B(6.6kV bus)

19.4 50.1

HV side of Start-up Tr.

(220kV )

6.4 17.4

LV side of Start-up Tr.

(11kV bus)

27.3 81

3.2 Parameters of main equipment

3.2.1 Transformers

3.2.1.1 Generator tansformer:

(1) Type single phase, outdoor

two winding

(2) Rating 3x270MVA

(3)Voltage ratio

HV/LV(tentative) 420±2×2.5%/22kV

(4) Winding connection and vector group

HV - Star LV - Delta Vector - Ynd11

(5) Impedance value 14%(tentative)

(6) Voltage regulation off-load tap changing

(7) System earthing (a) HV (b) LV

Effectively -

(8) Rated frequency 50Hz

(9) Cooling system ONAN/ONAF/OFAF

3.2.1.2 Unit tansformer:

(1) Type three phase, outdoor

two winding

(2) Rating 35MVA

(3) Voltage ratio HV/LV 22±8×1.25%/11.5kV


Dyn1



14


- Resistance


(9) Cooling system ONAN/ONAF

3.2.1.3 Station transformer:


split winding

(2) Rating 80/40-40MVA



YN,yn0-yn0

(5) Impedance value 16.5%(tentative)

(6) Voltage regulation on-load tap changing


Solidly Earthed Resistance



3.2.1.4 Start-up tansformer:


two winding

(2) Rating 31.5MVA



YN,yn0

(5) Impedance value 10.5%(tentative)

(6) Voltage regulation on-load tap changing


Solidly earthed Resistance



3.2.1.5 Unit auxiliaries tansformer:

15


two winding

(2) Rating 16MVA



D,yn11




Resistance Resistance



3.2.1.6 Station auxiliaries tansformer:


two winding

(2) Rating 5MVA



D,yn11




Resistance Resistance



3.2.1.7 Service auxiliaries tansformer:

(1) Type three phase, indoor

two winding，dry type

(2) Rating match the requirement

(3) Voltage ratio HV/LV 11/0.433 kV or

6.6/0.433 kV

16


Dyn11

(5) Impedance value match the requirement



Resistance Solidly earthed


(9) Cooling system ONAN

3.2.2 400kV and 220kV switchyard equipments

3.2.2.1 Circuit Breaker

400kV 220kV

(1) Type SF6,outdoor SF6,outdoor

(2) Nominal voltage 400kV 220kV

(3) Highest System voltage 420kV 245kV

(4) Short circuit breaking current

40kA for 1sec. 40kA for 1sec.

(5) Making current (peak) 100kA 100kA

(6) One minute power frequency withstand voltage

630kV(rms) 460kV(rms)

(7) Lightning withstand voltage (peak)

1425kV 1050kV

(8) Creepage distance 25mm/kV 25mm/kV

(9) Rated frequency 50Hz 50Hz

3.2.2.2 Isolator

400kV 220kV

(1) Type outdoor, double break type outdoor, double break type




630kV(rms)

(a) Between poles and earth


(b) Across isolating distance


17

(5) Lightning withstand voltage (peak)

(a) Between poles and earth

1425kV 1050kV

(b) Across isolating distance

1425kV 1200kV

(6) Main blade Motor & Manual Motor & Manual

(7) Earth blade Motor & Manual Motor & Manual



3.2.2.3 Current transformer

400kV 220kV

(1) Type Outdoor, SF6 or oil filled

hermetically sealed

Outdoor, SF6 or oil filled

hermetically sealed



(4) No. of cores (5) Primary current ratio

Refer SLD of Main

connection

Refer SLD of Main

connection

(6) Secondary current 1A 1A



3.2.2.4 Capacitor voltage transformers

400kV 220kV

(1) Type Outdoor, oil filled

hermetically sealed

Outdoor, oil filled

hermetically sealed



(4) No. of primary / secondary windings (5) Primary / secondary winding voltage

Refer SLD of Main

connection

Refer SLD of Main

connection



3.2.2.5 Lightning arrestors

18

400kV 220kV

(1) Type outdoor, gapless outdoor, gapless


(3) Discharge class 20kA. 10kA.



3.2.3 Bus duct

3.2.3.1 Isolated phase bus duct (IPBD)

(1) Type Continuous,enclosed type

(2) Type of cooling self-cooling

(3) Material of conductor Aluminum

(4) Material of enclosure Aluminum

(5) Rating of current Match the requirement

3.2.3.2 Segregated Phase Bus Ducts (SPBD)

(1) Type Continuous,enclosed type

(2) Type of cooling Natural air

(3) Material of conductor Aluminum

(4) Material of enclosure Aluminum

(5) Rating of current Match the requirement

11kV and 6.6kV equipment shall be suitable for un-earthed (non-effectively) system. And

short-circuit withstand capability of 11kV and 6.6kV equipment shall be 40kA for three (3)

seconds.

3.2.4 Switchgear

3.2.4.1 HV switchgear

11kV 6.6kV

(1) Type indoor, metal clad indoor, metal clad

(2) Nominal voltage 11kV 6.6kV

(3)Maximum system

voltage

12kV 7.2kV

(4) phases and frequency 3-phase,50Hz 3-phase,50Hz

(5) One minute power 28kV(rms) 20kV(rms)

19

frequency withstand voltage

(6) Short circuit current rating and duration

40kA for 1 sec 40kA for 1 sec

(7) Momentary withstand current

100kA(peak) 100kA(peak)

(8) System neutral earthing

Resistance earthed Resistance earthed

(9) Material of bus bars Aluminium Aluminium

(10) Enclosure IP4X IP4X

3.2.4.2 LV switchgear

415/240V

(1) Type indoor, metal clad

(2) Nominal voltage 415V

(3) phases and frequency 3-phase,4-wire 50Hz


2.5kV(rms)

(5) Short circuit current rating and duration

50kA for 1 sec

(6) Momentary withstand current

125kA(peak)

(7) System neutral earthing

Solidly earthed

(8) Material of bus bars Aluminium

(9) Enclosure IP-54

4 Generator and excitation

4.1 Type of generator

The synchronous generator shall be hydrogen/water cooled and directly driven by the

steam turbine at 3000 rpm.The Generator shall be 3 phase, 2 pole, with phase and

neutral terminals brought out for connection to isolated phase bus duct.

4.2 Rating

(1) Type QFSN-660-2

(2) Rated output 660MW

(3) Power factor 0.85(lagging)

(4) Terminal voltage 22kV

20

(5) Frequency 50Hz

(6) Short Circuit Ratio Not less than 0.48

(7) Class of Insulation

Class F but limited to class B temperature rise

(8) Efficiency 98.8%

(9) The maximum

continuous rating

Correspond to the output

of turbine

(10) Cooling system

Stator coil Water inner-cooled

Rotor coil Hydrogen inner-cooled

Stator core Hydrogen cooled

4.3 Design Criteria

The Generator shall be capable of withstanding, without injury, a three phase short

circuit at the terminals for three (3) seconds when operating at the rated output and

power factor, at 5% over voltage with fixed excitation.

Generator shall be capable of continuous operation at rated output through out the

frequency range of 47.5 to 51.5 Hz and voltage range of of +/-5% or absolute sum of

combined voltage and frequency variation of 5% without exceeding class B temperature

limits.

4.4 Excitation system

A complete generator excitation and voltage regulating system shall be provided with the

generator. The excitation system shall be static and the excitation system shall meet the

performance requirements of generator.

The excitation system provides control of generator terminal voltage by controlling

current supplied to the generator field. The AVR shall be digital type and have dual

automatic channels with a follow-up control to ensure a smooth change-over from one to

another. AUTO/MANNUAL control mode shall be provided. Some of the protective and

limit circuits are volts/hertz regulator, reactive current compensator, over excitation/

under excitation limiters, and field earth detection, and power system stabilizer and so on.

Excitation transformer shall be dry type and starting power of excitation shall be supplied

from 415V auxiliary system.

The excitation system is consists of the following main equipments: Excitation

21

transformer(ET), Automatic Voltage Regulator(AVR), Thyristor rectifier cubicle, field

breaker cubicle, excitation-starting device，excitation control and protection devices, etc.

All the equipments of excitation system shall be located at 0m level of main building.

5 Description of electric equipment layout

5.1 Layout of Generator Output system

The I.P.B.D. system shall transfer power from the generator terminals to the LV winding

terminals of the generator transformer, Tap off busducts for Unit Transformers ,excitation

transformer and Voltage Transformer & Surge Protection (VT & SP) cubicles shall be

provided. The generator neutral shall be connected to the neutral grounding transformer.

A resistor shall be connected across the secondary of this transformer.

The bus duct shall be self-cooling. The bus duct shall be pressurized with clean, dry

compressed air to prevent condensation and infiltration of dust into the enclosures,and

the bus duct shall be equipped with heater to prevent condensation during times out of

service.

5.2 Layout of GT UT & ST

Generator transformers(GT) , unit transformers(UT)/unit auxiliary transformers (UAT) and

station transformers(ST)/station auxiliary transformers(SAT) shall be all located outside

column A of turbine house.The central line of GT shall be 57 meters in front of column A

of turbine house, UTs shall be arranged between column A of turbine house and the

corresponding GT, and STs shall be arranged nearby the corresponding GT. SAT-1A,1B

and UAT-1A,1B shall be arranged together between GT-1 and GT-2, UAT-2A,2B shall be

arranged together between GT-2 and GT-3, UAT-3A,3B shall be arranged at the right

side of GT-3.

3 nos. 400kV surge arrester shall be arranged in front of each GT at the HV side.The

11kV side of UT and ST shall be connected to 11kV switchgears through non-segregated

phase bus duct. The 6.6kV side of UAT/SAT shall be connected to 11kV switchgears

through cables.The 11kV side of STT shall be connected to 11kV switchgear through

11kV cable.

Fire walls shall be set between single-phase of GT/unit transformers ect.

5.3 Layout of 400kV switchyard

22

A 400kV switchyard shall be provided for evacuation of power generated at the plant.

The 400kV switchyard shall adopt 1&1/2 breaker scheme. The 400kV switchyard shall

have 12 bays.The standard length required for a 400kV bay shall be 27 meters. Rating of

the main bus of 400kV switchyard shall be 4000A and short circuit rating of 400kV main

bus shall be consided as 40kA rms &100kA Ap. ACSR conductor shall be adopted for

the 400kV switchyard. For each 400kV incoming/outgoing line isolators and CVTs shall

be set, and WTs for outgoing line.The switchyard shall be provided with access ways

near the current transformers and circuit breakers.

The switchyard shall be enclosed wall around for safety and to prohibit unauthorized

persons from entering.The dimensions of the 400kV switchyard shall be 240 mtr.

(N/S)x220 mtr.(E/W).

5.4 Layout of 220kV switchyard

A 220kV switchyard shall also be provided to derive start-up power for the power plant.

Start-up transformer and 220kV electric equipments(i.e. CB,CT,Isolators) shall be

arranged at 220kV switchyard.

Start-up transformer shall be connected to 220kV outgoing line through a 220kV circuit

breaker. For this, space of 39 mtr.(N/S)x220 mtr.(E/W) shall be provided in the layout for

220kV switchyard.

5.5 Layout of HV/LV switchgear

5.5.1 Layout of HV switchgear

The 11kV start-up section shall be located in a switchgear room near the start-up

transformer.

The 11kV/6.6kV unit/station sections shall be all located on 0.0m and -3.0m-0.0m for

cable vault in turbine house between column A and column B. For No.1 unit, the 11kV

unit and station section- A/B shall be located between column 11 and column 12, 6.6kV

unit section-A/B shall be located between column 12 and column 13,11kV start-up

section-A/B and 6.6kV station section-A/B shall be located between column 13 and

column 14.And for No.2 & No.3 unit, the 11kV unit and station section- A/B shall be

located between column 24 and column 25/column 26 and clumn 27 respectively,and

6.6kV unit section-A/B shall be located between column 25 and column 26/column 27

and column 28 respectively.

Cable entry shall be from bottom and busduct entry shall be from top.

23

5.5.2 Layout of LV switchgear

The 0.415kV unit sections shall be all placed on 8.5m,and 5.5m-8.5m for cable vault. in

turbine house between column A and column B.

The 0.415kV station sections shall be placed on 8.5m floor in turbine house next to

corresponding 6.6kV unit sections.

ESP switchgears for each unit shall be placed in corresponding ESP switchgear room.

LV switchgears of other auxiliary systems in the plant shall be centralized placed at

corresponding switchgear rooms.

Cable entry shall be from bottom and busduct entry shall be from top. LV service

transformers shall be connected to their respective PCC through non-segregated-phase-

bus-duct.

6 DC System & UPS

6.1 DC System

The DC Power Supply System provides a reliable source of power for critical control

and power functions during normal and emergency plant operating conditions.

6.1.1 Major Components

(1) Unit 220V DC system for power and control

This DC System shall consist of the following major components:

a) Two (2) x 100% rated 220V, 1300Ah Nickel Cadmium type battery for each unit

b) Two (2) x 100% battery charger (comprising float cum boost function) for each unit,

rated current of each charger is 21X30A.

c) DC switchboard with two bus sections and a bus coupler to distribute 220V DC

power to DC loads.

(2) 220V DC system for 400kV&220kV Switchyard

This DC System shall consist of the following major components:

a) Two (2) x 100% rated 220V, Nickel Cadmium type battery.

b) Two (2) x 100% battery charger (comprising float cum boost function).

c) DC switchboard with two bus sections and a bus coupler to distribute 220V DC

power to DC loads.

(3) Three sets of 80Ah Auxiliary plant 220V DC system

Some essential auxiliary plant shall be provided with one set of 220V 80Ah DC system. It

consists of 30A battery chargers, DC incoming and distribution panels. Auxiliary plant

24

battery shall be ‘Valve regulated sealed lead acid’ type.

6.1.2 Description

The battery chargers will receive 3-phase, AC power from 415V switchboard. Under

normal operating conditions, The chargers will continuously float charge the batteries

while simultaneously supplying power to the DC loads. Each charger will be capable of

boost charging a fully discharged battery to a fully charged condition within 12 hours

while simultaneously supplying power to the DC loads.

Under abnormal or emergency conditions when power from the AC Power Supply

(415V) System is unavailable, the batteries shall supply power to the DC control loads for

1 hours at least and to essential DC motors loads for 1.5 hours or 3 hours(only for seal oil

pump)at least. The chargers will boost charge the discharged batteries when 415 volt

power becomes available from the AC Power System.

A ground detection scheme will be provided to detect grounds on either polarity of

the DC Power Supply System for annunciation in the Central Control Room.

The cubicles of unit DC system are located in DC & UPS distribution room which

located in the 6.9 meters floor of central control building.

The cubicles of switchyard DC system are located in 400kV switchyard relay room.

6.2 UPS

In this project, each unit shall be provided with one set of parallel redundant (Rated

capacity: 2X125kVA)Uninterruptible Power System (UPS) and unit UPS shall be applied

for essential function such as unit distribution control system (DCS), automatic device,

intelligent device, I&C protection, adjusting device, I&C instrument etc. Three (3) unit

shall be provided a common parallel redundant (Rated capacity: 2X25kVA)

Uninterruptible Power System (UPS) and common UPS shall be applied for essential

function such as common DCS, automatic device, intelligent device, I&C instrument etc.

UPS shall be AC 415/240V input, AC 240V output, 50Hz.

Unit and common UPS system shall be of parallel redundant consisting of 2X100%

chargers, 2X100% rectifier, 2X100% inverters, 2X100% static-over switch, 100% Battery

and bypass maintenance switch, isolate transformer, regulating transformer, AC

distribution board etc. DC supply for UPS shall be derived from dedicated Batteries and

assembled in panel. The batteries shall be sizing to supply the total load for a period of 1

hour in the event of loss of normal supplies.

25

The cubicles of UPS system are located in DC & UPS distribution room which

located in the 6.9 meters floor of central control building.

7 Electrical Protection & Control & Automechanism

7.1 Protection

7.1.1 The protection systems will be digital, microprocessor based devices with monitoring,

measurement and communication capability.

Two sets of integrated protection relay (redundant scheme) will be provided only for

each generator. The protection relay functions shall be grouped in two groups each with

separate CT and VT inputs , trip channel and trip device. Each integrated protection relay

(each cubicle) includes main and back-up protection functions ,and which using a common

CT and VT inputs. The others electric devices such as generator transformer, unit

transformers, station transformers and startup transformer shall be provided one set of

integrated protection relay, and main and back-up protection functions shall be separate.

7.1.2 The G-T unit protections shall be classified to initiate the following three classes of

tripping:

a) Class-A trip mode for critical electrical faults in the generator, generator

transformer and unit transformer systems.

In this mode of tripping, for faults in the GT and UT, the unit is directly tripped by

simultaneously shutting down the turbine and opening the GT HV circuit breaker and UT LV

side circuit breaker along with tripping of the excitation system.

b) Class-B trip mode for non-critical electrical faults in the generator system.

In this mode of tripping, the turbine is shut down first and the generator is tripped

subsequently by a low forward power relays by opening the GT HV circuit breaker and

tripping of the excitation system. This mode of tripping is adopted for all mechanical faults

and non-critical electrical faults.

c) Class-C trip mode for abnormal operating conditions and system disturbances.

In this mode of tripping, the generator is isolated from the power system by tripping

the GT HV circuit breaker for faults beyond the generator system. In this case, the unit

continues to run with HP-LP bypass system and supplies the auxiliary loads.

Accordingly, all the relays shall be divided into the above three modes of tripping.

7.1.3 Protection scheme

26

(1) Generator Protection

The Generator protection relay will be provided comprising the following:

i) Differential

ii) Stator Interturn fault

iii) Stator earth fault 95%

iv) Stator earth fault 100%

iv) Loss of excitation

v) Negative phase sequence over current

vi) Reverse power

vii) Rotor earth fault

viii) Under/over frequency

ix) Under/over voltage

x) Thermal overload

xi) Voltage restrained overcurrent

xii) over excitation

xiii) Out of step

xiv) Back-energization protection

xv) Startup/shutdown protection

xvi) Low forward power

xvii) Cooling water-loss

xviii) ETS (from I&C)

xix) VT and CT supervision

(2) Transformer Protection

a Generator Transformer

The generator transformer protection system will be provided comprising the following:

i) Overall differential

ii) Differential

iii) Restricted earth fault

iv) Complex-voltage lockout overcurrent

v) Earth fault

vi) Backup earth fault

vii) Over excitation

27

viii) Bucholz

ix) Winding temp

x) Oil temp

xi) Pressure relief

xii) Oil level

xiii) VT and CT supervision

b Excitation Transformer

The excitation transformer protection system will comprise the following:

i) ET instantaneous overcurrent

ii) ET overcurrent

iii) ET winding thermal overload

iv) ET winding temp.

c Unit Transformer

The unit auxiliary transformer protection system will comprise the following:

i) Differential

ii) Restricted earth fault

iii) Complex-voltage lockout overcurrent

iv) LV branch low-voltage lockout overcurrent

v) LV side earth fault

vi) LV side backup earth fault

vii) Transformer Buchholz

viii) Winding temperature

ix) Oil temperature

x) Pressure relief

xi) Oil level

xii) VT and CT supervision

All the protection relays mentioned above shall be housed in the electrical relay room

which located in the 13.7 meters floor of central control building.

d Station Transformer & Startup Transformer

The station service transformer & startup Transformer protection system will comprise the

following:

i) Differential

28

ii) HV/LV side restricted earth fault

iii) Over excitation

iv) Complex-voltage lockout overcurrent

v) HV side earth fault

vi) HV side backup earth fault

vii) LV branch low-voltage lockout overcurrent

viii) LV side earth fault

ix) LV side backup earth fault

x) Transformer Buchholz

xi) Winding temperature

xii) Oil temperature

xiii) Pressure relief

xiv) Oil level

xv) VT and CT supervision

The protection relays mentioned above shall be housed in 400kV switchyard relay

room.

(3) 11&6.6kV Medium Voltage Switchgear

The protection relay will be selected and set to provide a coordinated tripping

philosophy to mitigate the faulted condition and to provide an integrated control, monitoring,

measurement and protection function.

Incoming (Source) Breakers The incoming breakers will provide the following minimum protections:

i) Overcurrent

ii) Earth fault

Feeder Breakers The feeder breakers will provide the following minimum protections:

i) Instantaneous overcurrent

ii) Overcurrent

iii) Earth fault

Tie Circuit Breaker Each tie breaker will provide the following minimum protections:

i) Overcurrent

ii) Earth fault

29

Unit Service Transformer Feeder Each unit service transformer will provide the following minimum protections:

i) Differential protection (for transformer rated ≥2000 kW)

ii) Instantaneous overcurrent

iii) Restricted earth fault

iv) Overcurrent

iii) HV/LV side earth fault

iv) HV/LV side backup earth fault

v) Overloads.

vi) High winding/oil temperature.

Motor Feeder Each motor feeder will provide the following minimum protections:

i) Differential protection (for motor rated ≥ 2000 kW)

ii) Thermal overload

iii) Instantaneous over-current & overcurrent

iv) Earth fault

v) Backup earth fault

vi) Unbalance loading/Single phasing

vii) Locked rotor (50 L/R) or stalling

viii) Under-voltage

(4) 415/240V Unit Service Switchgear

415/240V unit service switchgear (USS) feeders will provide the following minimum

protection features:

i) Thermal overload protection

ii) Phase fault protection

iii) Earth fault protection

(5) 415/240V Motor Control Centers

Motor Control Centers (MCC) will provide the following minimum protections:

i) Short circuit

ii) Thermal overload protection

iii) Stalling protection

iv) Phase failure protection

30

v) Earth fault protection(specialty earth fault protection device shall be selected for

motor rated above 55 kW)

vi) Under-voltage

7.2 400kV & 220kV Switchyard Computerized Monitoring And Control System

The 400kV & 220kV Switchyard Computerized Monitoring And Control

System(SCMCS) shall be an integrated system comprising control & monitoring cell, fiber-

optic cable redundant communication buses, centralized 100% redundant computerized

operator cum engineering stations, man-machine interfaces (MMI), printers, gateways

modems, etc. It shall perform the following main functions:

• ON/Off interlocked operation of 400kV&220kV circuit breakers and disconnection

switches (isolators).

• Synchronizing with voltage, phase and frequency checking prior to breaker closing.

• Monitoring the status of circuit breakers, disconnect switches, earth switches and

protective devices.

• Measurement, recording and display of instantaneous and integrated electrical analog

quantities with time-tagging.

• Monitoring the trip circuits of circuit breakers.

• Monitoring the number of operations, operating time and integrated magnitude of

interrupted current of circuit breakers.

• Fault recording and analysis.

• Sequence of event recording.

• Trending and archiving

• Graphic mimic representation

• Generating and acknowledging/resetting of alarms

• Self-diagnostics and self-monitoring

Two (2) nos. Operator station for SCMCS shall be located in Switchyard Control

Room which will be the main operating site and one (1) in Central Control Room (CCR) of

power plant as a backup.

Information exchange shall be provided between plant DCS and SCMCS through a

suitable, fast, reliable and redundant communication.

31

The cubicles of SCMCS system are mainly located in 400kV switchyard relay room

and switchyard control room.

7.3 Control And Instrumentation

The control, indication, measurements, annunciation and sequential event logging for

each generator and its subsystems and complete unit and station auxiliary power supply

system shall be provided in DCS system through Operator station/keyboard.

The electrical equipment which shall be controlled or supervised in DCS are as follows:

----Generator-transformer unit and excitation system

----Station transformer & startup transformer

----11kV&6.6kV power supply system

----415/240V power supply system serving main building system including ESP PC

----Diesel generator and emergency auxiliary power system

----HV/LV Motor serving main building system

----Unit DC system（supervising only）

----Unit & common UPS（supervising only）

Meanwhile, control switches or pushbuttons which are essential for safe shutdown

under emergency condition shall be provided as follows: generator circuit breaker tripping,

fielding circuit breaker tripping, diesel generator start.

A separate hardwired Generator Control Panel (GCP) shall be provided for each

generator for auto/manual synchronising of generator. The manual synchronizing initiated

by the operator shall be possible via a synchro-check relay in the manual mode. Auto/

Manual selection for synchronizing of generator shall be provided in DCS. When the “Auto”

mode is selected, synchronizing shall be initiated from DCS through auto synchroniser.

When the “Manual” mode is selected, synchronizing shall be done from generator control

panel manually. In Generator Control Panel (GCP), the following meters for generator shall

be provided for safe shutdown of the units: ampere meter, voltmeter, frequency meter and

so on.

Energy metering panel(Energy accounting and audit meter) shall be provided in electric

relay room of central control building for generator, generator transformer, unit transformer

and station transformer. Main meter and standby meter shall be provided for generator

32

energy metering. For generator active energy (Wh) meter, accuracy class of 0.2s shall be

provided. For generator reactive energy(Var) meter, accuracy class of 1.0 shall be provided.

Auxiliary plant electrical system shall be controlled locally in related local control room

or PCs/MCCs. For auxiliary plant electrical system, essential meters shall be set on local

PCs/MCCs panels according to relevant standards.

For the detailed design criteria and scope of supply of DCS please refer to I&C

description.

7.4 Control System of Auxiliary Workshop

7.4.1 Coal Handling Plant Control System

A coal handling PLC(Programmable Logic Controller) system shall be provided to

control and monitor the coal handling plant.

A set of CCTV system consist of monitor, main control computers and camera will be

provided for coal handing system.

Control system in coal handling control room include CRT and PLC which will be dual

redundant processor .All inputs/outputs shall be connected to I/O modules via intermediate

relays. Remote I/O station will be designed in coal bunker bay, Dual redundant

communication construction will be adopted between PLC local station and remote station.

The control system shall provide three distinct levels of control for the Coal Handling

Plant as follows:

Level 1 Monitoring from the Center Control Room

Level 2 Control from the Coal Plant Control Building

Level 3 Control from the field adjacent to the respective machinery item.

The coal handling plant shall be capable of being controlled in the following modes.

(a) Automatic Mode - the plant is started and stopped automatically in

accordance with the selected handling routines.

(b) Manual Mode - All drives can be started and stopped individually via the LCD

based on sequence requirement.

(c) Local Mode – All drives can be started and stopped by locally with select

switch with key.

(d) Emergency Mode - Should the controller fail emergency operation shall be

provided using the local control switches such as rope switches and emergency push

buttons.

33

The control system panels will be arranged in coal handling control room and remote

I/O room.

7.4.2 Control System of ESP

A process control, electrical control and instrumentation system(PLC) as a part of

electrical precipitator system necessary shall be provided to control and monitor Precipitator

collection process.

The PLC panels will be installed in ESP distribution room and CRT will be arranged in

ESP control room which located in ESP control building. The information of ESP can be

sent to DCS via communication interface and the important signals or command (ie, ”

start”, ”stop”, ”local/remote mode”, “precipitator operate” ,” precipitator fault” etc.) will be

connected to DCS by hard-wired connection.

Three distinct levels of operation shall be provided.

Level 1 Remote monitoring from Central Control Room

Level 2 Remote Control and Monitoring from ESP control room

Level 3 Local manual control of motors and valves.

7.5 Change-Over Mode

One automatic microprocessor based high-speed busbar transfer device will be

provided for each unit 11kV&6.6kV section.

The automatic change over for 415V breaker shall be initiated and controlled by the

DCS system.

7.6 Unit Fault Wave Recorder

A set of electric fault wave recorder shall be provided for each unit.

Mostly the following important electric information shall be recorded for fault event

analysis: main protection signals, status of electric equipment and major electric parameter

of main generation circuits.

Sampling rate per cycle of electric fault wave recorder shall be above 10kHz.

8 Lightning protection & Earthing system

8.1 Lightning protection system

Lightning protection system shall mainly consist of lightning rods and horizontal roof

conductors.

For cooling towers shall comprise of horizontal circumferential conductors at the top. For

34

switchyard, lightning protection shall be provided. Each down conductor shall be

connected to a rod electrode, which in turn shall be connected to the station earthing

system.

Surge arresters shall be mounted on the HV terminals of the generator transformers,

station transformers and the 400kV/220kV outgoning lines to protect the transformers

and 400kV/220kV switchyard equipments from voltage surges.

Lightning protection shall also be provided for Boiler and station building as well as other

buildings as required by the relevant codes.

8.2 Earthing system

Earthing system shall consist of earth grids and electrodes buried in soil in the plant area,

embedded in concrete inside the buildings to which all the electrical equipment, metallic

structures shall be connected to have earth continuity for safety reasons. Conductors

buried in ground or embedded in concrete shall be galvanized steel and galvanised steel

rod electrodes of suitable diameter and length shall be adopted.

Earthing conductors in outdoor areas shall be installed at a minimum depth of 600 mm.

The earthing conductor shall be sized for a life of 30 years under the corrosive conditions

of site.

9 Lighting and maintenance system

9.1 Power supply system

9.1.1 Normal lighting

The normal A.C. lighting system shall be provided for throughout the plant, The A.C.

lighting system shall be of 415/240V,3-phase 4-wire, 50HZ, neutral directly earthed

system. The voltage for lamp shall be of 240V.

The lighting of main building shall be supplied by normal lighting panels which installed in

LV auxiliary switchgear room, The lighting of other auxiliary building shall be supplied by

the PCs or MCCs nearby.

9.1.2 Emergency lighting

Emergency D.C. lighting shall be arranged in important areas of main building and

central control room and the main entrances. D.C. lighting system shall derive power

from emergency lighting inverter.

The lamp with self-contained battery shall be used for the emergency lighting in isolated

35

areas, such as coal handling system, electrostatic precipitator control building. 20﹪

percentage of emergency (DG based)lighting and battery (plant as self contained)

backed lighting to be indicated as against of total lighting.

9.1.3 Table of Lighting Levels

Normal Lighting Emergency Lighting

(Lux) (Lux)

PCR 300 30

Offices 300

Toilets 30

Meal Rooms 200

Laboratories 300

Workshops 100 10

Locker Rooms 100 10

Switchrooms (electrical) 100 10

Maintenance Area 150

Cable Rooms (or Floor) 30 10

Turbine Bay Main

Lighting 160 10

Walkways 30 10

Boiler 100 10

Coal Plant operating

Locations within Buildings 100 10

Tripper Conveyor Floor 100 10

Tunnels (if required) 40 10

Access Ladders/Stairs 40 10

External Storage Tanks 10 -

External Plant Building 50

Street Lighting Security 15

36

Telephone Booths 300 -

9.1.4 Maintenance system

The maintenance power box shall be located in every floor of the main building and the

other auxiliary plant .The maintenance power box shall supply to welding machine,

maintenance lighting and the other electric tool, The maintenance power supply system

shall be of 415/240V ,3 -phase 4- wire ,50HZ, neutral directly earthed system.

The maintenance power for the coal handling system, water supply system and the other

auxiliary buildings shall be supplied by the PCCs or MCCs nearby.

9.1.5 Maintenance Lighting

The maintenance lighting voltage shall be 24V, which shall derive power from the

240/24V step-down transformer from 240V socket. The maintenance voltage for the

boiler shall be12V,which shall be supplied by the 240/12V transformer from the low

voltage socket box in every floor.

9.1.6 Lighting fixtures

High pressure sodium (H.P.S) fixture shall be used as outdoor street lighting, indoor

Lighting System (Turbine house, C.W.P house, and etc),

Fluorescent fixture shall be used for general indoor lighting (Admin. Building, electrical

room, switchgear room, main control building, and etc).

Incandescent fixture shall be used as essential DC lighting. 9.2 Control of the Lighting System

The lighting for main building shall be generally concentrate controlled by MCB in lighting

distribution box.

Lighting in individual unattended room shall be controlled by local switches at entrance or

exit.

The lighting for road, transformer and other outdoor area shall be controlled by photo-

electricity cell and be manual or automatic controlled in local lighting distribution box with

a by-pass switch.

The lighting for boiler body shall be remote controlled in boiler house grade floor or

concentrate controlled in respective lighting distribution box.

9.3 Lighting distribution box

The lighting distribution box shall be located in the areas to conveniently operated, and

37

lighting distribution box shall be surface mounted in main building and built-in mounted in

office and control building area. It shall be provided with a incoming circuit breaker .The

branch circuit breaker shall be of miniature molded case, The lighting distribution box

shall be in modular steel structure with front lockable hinged door.RCCB(residual current

circuit breaker) to be provided with only socket circuits for protection against earth

leakage.

9.4 Cable, Wire

The roadway lighting cables shall be PVC insulated, steel strip armoured and PVC

sheathed overall.

The connection cable between lighting distribution box and aircraft warning lighting

fixtures shall be PVC insulated, steel wire armored and PVC sheathed overall.

The PVC insulated copper wire shall be used in other area. The branch circuit cable

section shall be of minimum 2.5mm2.

9.5 Raceway

The lighting wire shall be laid in hot-dip galvanized steel pipe .

The minimum diameter of hot-dip galvanized steel pipe shall be 20mm.

The conduit in turbine house and boiler house shall be generally exposed and embedded

where is subject to mechanical injury.

The sealed junction box shall be provided in exposed conduit system.

10 Cables & Cabling

10.1 Cables

(1) HV Cables

11kV and 6.6kV unearthed grade cables shall be used for the plant as HT cables. HT

cables shall be unearthed grade with stranded & compacted aluminium conductors,

extruded XLPE insulated. HV Cables shall have FRLS PVC outer sheath. Buried cables

shall be armoured type.

(2) LV Cables

LT Power Cable shall be 1100 V grade, single / multicore, stranded aluminium conductor,

XLPE insulated, with FRLS PVC inner sheath and outer sheath made of FRLS PVC.

(3) Control Cables

Control cables shall be 1100V grade, multicore, high conductivity annealed plain copper

38

conductor, Extruded PVC insulated, with Extruded PVC inner sheath and outer sheath

made of Extruded FRLS PVC.

10.2 Cabling

(1) General

Cable racks and cable trenches shall be adopted for cable carrier system. Overhead

racks and cable trenches shall be of different sizes depending on the number of cables

laid in that route.

(2) Cable tray

All cable trays shall be of ladder type construction and be made of galvanized steel.

Spacing between the cable tray supports shall be not more than 1500 mm, except fittings

(elbows, tees, etc.) which shall be supported at each splice.

Cable tray fittings shall have a radius equal to or greater than the minimum bending

radius of the cables they contain. At least a 150 mm clearance shall be maintained

between the top of a tray and beams, piping, or other obstacles to facilitate installation of

cables in the tray.

(3) Conduit

Conduit systems shall be used in supporting and protecting electrical cable. Galvanized

rigid steel conduit shall be used for all conduit

Design basis Report

Documents

Transcript of Design basis Report