Reactor Protection

(1)

REACTOR PROTECTION

PREPARED BY

GOPALA KRISHNA PALEPU

ADE/MRT(PROTECTION)

[email protected], Mobile:9440336984

(2)

MAIN-1 & MAIN-2

PROTECTION FOR

SHUNT REACTOR

ADOPTED IN

ONE AND HALF

CIRCUIT BREAKER

SCHEME

PREPARED BY

GOPALA KRISHNA PALEPU

ADE/MRT(PROTECTION)

(3)

BASICS OF SHUNT REACTOR

1. TYPES OF REACTORS :

A. BASED ON REACTOR CONNECTION i. SHUNT REACTOR.

ii. SERIES REACTOR.

B. BASED ON REACTOR LOCATION i. BUS REACTOR

ii. LINE REACTOR

C. BASED ON CONTROL

i. 3-PH OIL IMMERSED REACTOR WITH GAPPED IRON CORE.

ii. THYRISTOR CONTROLLED REACTOR (STATIC VAR COMPENSATOR)

(APTRANSCO UTILISING SHUNT REACTORS FOR BUS & LINE IN 400KV NETWORK) 2. NEED OF SHUNT REACTOR:

A. LINE REACTOR

SHUNT REACTORS ARE USED IN ORDER TO COMPENSATE FOR THE CAPACITIVE SHUNT REACTANCE OF TRANSMISSION LINES. THE REACTOR IS CONNECTED PARALLEL TO THE LINE. THE LOCATION OF REACTOR IS OUT GOING SIDE OF LINE i.e AFTER CIRCUIT BREAKER. LENGTH OF LINE IS MORE THERE MAY BE VOLTAGE IS RAISING DUE TO FARANTI EFFECT(CAPACITANCE) DURING CHARGING. IN CASE OF ZONE-2 (OPEN JUMPER) FAULT, THE FAULT CLEARED BY REMOTE END IS FAST, BUT THIS END IT WILL TAKE TIME DELAY DUE TO ZONE-2. DURING THIS TIME, VOLTAGE MAY RAISING. SO, LINE REACTOR IS USED FOR CONTROLLING THE SWITCHING OVER VOLTAGES AND SAFEGUARD THE OPERATING EQUIPMENT. NORMALLY IT IS ALWAYS IN SERVICE. NORMALLY BOTH ENDS LINE REACTORS ARE PROVIDED. THE ELECTRICAL INTERLOCK IS PROVIDED THAT IF REACTOR ISOLATOR CLOSSED POSITION ONLY WILL GIVE PERMIT TO CLOSE THE LINE ISOLATOR. SIMILARLY FOR OPENING REACTOR ISOLATOR THE LINE ISOLATOR SHOULD BE IN OPEN POSITION. NEUTRAL REACTOR CONNECTED BETWEEN THE STAR POINT OF EHV SHUNT REACTOR AND THE GROUND, LIMITS THE SECONDARY ARC CURRENT TO A LOW VALUE OF AROUND 10 AMPS TYPICALLY FOR 400KV SYSTEM TO ENSURE COMPLETE DE-IONISATION OF ARC PATH WHEN EHV SYSTEM DEVELOPS A SINGLE LINE TO GROUND FAULT. ARC EXTINCTION DURING LINE SINGLE-PHASE AUTORECLOSE DEAD TIME IS ASSISTED BY THIS NEUTRAL REACTOR.

(4)

B. BUS REACTOR

THE REACTOR IS CONNECTED PARALLEL TO THE BUS i.e LIKE A FEEDER/LINE.

DURING LIGHTLY LOADED CONDITIONS THERE MAY BE POSSIBULITY OF RAISING

BUS VOLTAGES. FOR SAFEGUARD THE OPERATING EQUIPMENT BUS REACTORS

ARE UTILISING. NORMALLY IT IS NOT IN SERVICE. WHENEVER THE VOLTAGE

RAISES TO 4%TO 5% MORE THAN THE RATED VOLTAGE THIS MAY BE KEPT IN

SERVICE AND 2% TO 3% LESS THAN THE RATED VOLTAGE THIS MAY BE KEPT OUT

OF SERVICE.

3. SELECTION OF REACTOR

A. LINE REACTOR

NORMALLY LINE REACTORS ARE PROVIDED IF THE LINE IS MORE OR EQUAL TO

250KM. IN APTRANSCO NETWORK MAXIMUM LENTH OF LINE IS 350KM. AS PER

SYSTEM STUDIES RECOMANDATIONS IF LINE LENGTH IS 250KM TO 300KM 50MVAR

REACTOR IS TO BE USED. IF MORE THAN 300KM 63MVAR REACTOR IS TO BE

USED.

B. BUS REACTOR

NORMALLY BUS REACTORS ARE PROVIDED IF THE SUBSTATION BUS VOLTAGE IS

RAISING 5% MORE THAN THE RATED VOLTAGE DURING LIGHTLY LOADED

CONDITION. BASED ON THE SYSTEM STUDIES RECOMANDATIONS BUS REACTORS

ARE TO BE PROVIDED. CALCULATIONS ARE REQUIRED FOR PROVIDING BUS

REACTOR. IN THIS THERE IS NO STANDARDISATION.

4. LOCATION OF REACTORS WITH CAPACITY IN APTRANSCO

A. LINE REACTOR

1. 400KV KALAPAKA-KHAMMAM 1 AT BOTH ENDS – 63MVAR

2. 400KV KALAPAKA-KHAMMAM 2 AT BOTH ENDS – 63MVAR

B. BUS REACTOR

1. 400KV KALAPAKA SS – 2 X 50 MVAR

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5. PURPOSE OF SHUNT REACTOR PROTECTION

THE PURPOSE OF THE PROTECTION RELAYING IS TO DISCONNECT THE REACTOR AND LIMIT DAMAGE IN CASE OF INTERNAL SHORT CIRCUITS, EARTH FAULTS, INTERTURN FAULTS AND OVER VOLTAGE OR OVER LOAD.THE REACTOR FORMS CERTAIN

IMPEDENCE FOR RATED FREQUENCY, AND AS IT IS SHUNT CONNECTED, AS OVER LOAD MAY BE CAUSED BY OVER VOLTAGE OR HARMONICS IN VOLTAGE AND CURRENT.

6. PROTECTION DEVICES INBUILT OR MOUNTED ON REACTOR

A. OIL IMMERSED REACTOR USUALLY HAVE A GAS DETECTOR AND OIL SURGE. DETECTOR (BUCHHOLZ ALARAM & TRIP DEVICES), WHICH ARE EXCELLENT FOR DETECTING INTERNAL FAULTS.

B. TEMPARATURE MONITORS FOR OIL & WINDING PROVIDE GOOD OVER LOAD PROTECTION.

C. PRESSURE RELIEF DEVICE IS PROVIDED TO SAFE GUARD THE REACTOR FROM HIGH PRESURES.

7. REACTOR DIFFERENTIAL PROTECTION

IT IS WIDELY USED AS INSTANTANEOUS PROTECTION FOR SHORT CIRCUIT FAULTS WITH IN THE DIFFERENTIAL ZONE. THIS IS TREATED AS MAIN-1 PROT FOR REACTOR.

IT CAN BE OF HIGH IMPEDENCE TYPE OR OF A SENSITIVE CURRENT STABILISED TYPE. HIGH IMPEDENCE DIFFERENTIAL PROTECTION RELAYS REQUIRE AN EQUAL CT TURNS RATIO ON THE PHASE AND NEUTRAL SIDE. SENSITIVITY IS 5% OF NOMINAL REACTOR CT CURRENT.

8. BACK-UP PROTECTION

A VARIETY OF RELAYS ARE AVAILABLE.

A. OVER CURRENT & EARTH FAULT PROTECTION. ( 50, 50N, 51, 51N, 67, 67N - ANY COMBINATION OF THESE)

B. UNDER IMPEDENCE / DISTANCE ( Z<)(21R). C. NEUTRAL DISPLACEMENT PROTECTION (Un>). 9. RESTRICTED EARTH FAULT PROTECTION

IF, FOR SOME REASON, A SENSITIVE DIFFERENTIAL PROTECTION NOT CHOOSEN A RESTRICTED EARTH FAULT PROTECTION CAN BE UTILISED.

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SHUNT REACTOR (BUS & LINE)

(ONE AND HALF CIRCUIT BREAKER SYSTEM )

LINE 1

1-89 1-89A 1-52CB 1-CT

₃

3

3-89 3-89A 3-52CB 3-CT

3

2-52CB 2-CT 2-89A 2-89B 1-89L BUS-1 BUS-2 P1 P1 P1 P2 _P2 P2

UUU

LINE

SHUNT

REACTOR

1-89R

UUU

BUS

SHUNT

REACTOR

.

3-89R

UU

.

IL

INTER LOCK FACILITY: WHEN 1-89R CLOSES ONLY PERMIT TO CLOSE 1-89L AND

1-89L OPENS ONLY PERMIT TO OPEN 1-89R.

IL

1-PH NEUTRAL GROUNDING REACTOR

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REACTOR BUSHING CT INFORMATION

CAPACITY OF 400KV REACTORS : 50, 63, 80, 125 MVAR

NGR

SHUNT REACTOR

ITEM

Sr

NO

EARTH

SIDE

LINE SIDE

STAR / NEUTRAL SIDE

400KV / LINE SIDE

CORE-2

CORE-1

CORE-4

CORE -3

CORE-2

CORE-1

CORE-5

CORE-4

CORE-3

CORE -2

CORE-1

200/1

WTI

200/1

2000-

1000-500/1

2000-

1000-500/1

200/1

RATIO

1 NEUTRAN BUSHING CT : CORE-1 : BEFORE STAR FORMATION IN RYB PHASES

64 R

REF1/2

64 R

REF2

64 R

REF1

87 R

DIFF

MET

FOR 21L1

/TEED-2 /

BBC

FOR 21L2

/TEED-1 /

BBM

21 R

IMP

64 R

REF1

87 R

DIFF

PURPOSE

5 PS

PS

CLASS OF

ACURACY

4 1 OHM

1 OHM

10 – 5

– 2.5

OHM

10 – 5 –

2.5 OHM

1 OHM

R

CT

IN OHMS

3 200V

200V

Parameters of

WTI CT for each winding shall be

provided by the contractor

1.0 CL

AND

BURDEN

10 VA

1000-

500-250V

1000-

500-250V

200V

V

KNEE

FOR PS

& VA FOR

MET

2

(8)

SHUNT REACTOR PROTECTION

400KV SIDE

21R – 3Ph, REACTOR BACKUP IMPEDANCE RELAY OF

SUITABLY SHAPED CHARECRESTICS EITHER SINGLE /

DOUBLE ZONE TYPE.

CORE-3

87 BBC/BB-2

21L2

(M_CT+T_CT – R_CT)

87 TEED-2

(M_CT, T_CT, R_CT)

21L2

(M_CT+T_CT–R_CT)

CORE-4

87 BBM/BB-1

21L1

(M_CT+T_CT – R_CT)

87 TEED-1

(M_CT, T_CT, R_CT)

21L1

(M_CT+T_CT–R_CT)

CORE-5

64R - REACTOR RESTRICTED EARTH FAULT PROTECTION

OF1-POLE HIGH IMPEDANCE TYPE.(REF1)

CORE-2

87R – 3Ph, 2Wdg REACTOR DIFFERENTIAL RELAY EITHER

LOW or HIGH IMPEDANCE TYPE.

CORE-1

BUS

LINE

BUS

LINE

DOUBLE BUS & TRANSFER

BUS SYSTEM

ONE & HALF BREAKER

SYSTEM

CORES

(9)

SHUNT REACTOR PROTECTION

NEUTRAL GROUNDING REACTOR SIDE

-64 REF2

-64 REF1

CORE-1

STAR / NEUTRAL SIDE

87R – 3Ph, 2Wdg REACTOR DIFFERENTIAL RELAY EITHER

LOW / HIGH IMPEDANCE TYPE.

CORE-3

64R - REACTOR RESTRICTED EARTH FAULT PROTECTION

OF1-POLE HIGH IMPEDANCE TYPE .(REF1)

CORE-4

-64 REF 1 / 2

-64 REF1

CORE-2

WINDING TEMPARETURE OF REACTOR

CORE-2

METERING OF REACTOR

CORE-1

BUS

LINE

BUS

LINE

DOUBLE BUS & TRANSFER

BUS SYSTEM

ONE & HALF BREAKER

SYSTEM

(10)

UUU

LINE

SHUNT

REACTOR

.

1-PH NEUTRAL GROUNDING REACTOR

3

3 UUU

3

3 UUU

3

3 UUU

3

CORE -1 CORE -2 CORE -3 CORE -4 CORE -5 CORE -1 CORE -2 CORE -3 CORE -4 CORE -1 CORE -2

REACTOR BUSHING CT

INFORMATION

(11)

UUU

BUS

SHUNT

REACTOR

.

3

3 UUU

3

3 UUU

3

CORE -1 CORE -2 CORE -3 CORE -4 CORE -5 CORE -1 CORE -2 CORE -3 CORE -4

REACTOR BUSHING CT

INFORMATION

(12)

ONE & HALF BREAKER LINE & BUS SHUNT REACTOR PROTECTION SCHEME

87BB1 87BB2 CVT CVT VBB1 VBB2 79 25 79 25 79 25 VBB2 BF BF VL2 / VL1 ORVBB1 VL1 / VL2 ORVBB2 VBB1 FEEDER1 / LINE1 87L 21M2 CVT VL1 BF VL1 BUSBAR-1 BUSBAR-2 TEED-1 TEED-2

PROTECTION OF BUS REACTOR 21M1 VL1

VL1 / VBB1

VL2 / VBB2

FOR REACTOR PROTECTION &

METERING VOLTAGE SELECTION RELAYS FOR BUS-1, BUS-2& LINE ARE PROVIDED .

U U

U

U U

U

87R 64R OR 21R

U U

U

87R 64R VL1/VBB 1/VBB 2 VBB1/VBB2 21R

(13)

LINE/BUS REACTOR DIFFERENTIAL PROTECTION

(LOW IMPEDANCE DIFFERENTIAL PROTECTION)

3

R-CT HV BUSHING CORE-1 CTR: 200/1A CLASS: PS 1S2 1S2 1S2 1S1 1S1 1S1 P2 P2 P2 CT MB

3 3 3

R-CT STAR BUSHING CORE-3 CTR: 200/1A CLASS: PS 3S1 3S1 3S1 3S2 3S2 3S2 P2 P2 P2 CT MB

C

E

DISPLAY

ACTIVE START TRIP

RET 670

NORMALLY

LOW / HIGH IMPEDENCE

DIFFERENTIAL RELAY IS

USED FOR BUS / LINE

REACTOR

DIFFERENTIAL

PROTECTION

(14)

C

E

DISPLAY

ACTIVE START TRIP

RET 670

3

R-CT HV BUSHING CT CORE-1 CTR: 200/1A CLASS: PS R-CT STAR BUSHING CT CORE-3 CTR: 200/1A CLASS: PS P2 P2 P2 P2 P2 P2 P1 P1 P1 P1 P1 P1 1S2 1S2 1S2 3S2 3S2 3S2 1S1 1S1 1S1 3S1 3S1 3S1

LINE/BUS REACTOR DIFFERENTIAL PROTECTION

(HIGH IMPEDANCE DIFFERENTIAL PROTECTION)

IN CASE OF REACTOR BUSHING CT P2 IS AWAY FROM REACTOR & P1 IS TOWARDS REACTOR

NORMALLY

LOW / HIGH IMPEDENCE

DIFFERENTIAL RELAY IS

USED FOR BUS / LINE

REACTOR

DIFFERENTIAL

PROTECTION

(15)

C

E

DISPLAY

ACTIVE START TRIP

RET 670

3

P2 P2 P2 P2 P2 P2 P1 P1 P1 P1 P1 P1 2S2 2S2 2S2 4S2 4S2 4S2 4S1 4S1 4S1 2S1 2S1 2S1

LINE/BUS REACTOR REF PROTECTION

(NGR IS NOT AVAIALBLE) R-CT HV BUSHING CT CORE-2 CTR: 200/1A CLASS: PS R-CT STAR BUSHING CT CORE-4 CTR: 200/1A CLASS: PS

NORMALLY

HIGH IMPEDENCE

VOLTAGE/CURRENT

OPERATED SINGLE

POLE RELAY IS USED

FOR BUS / LINE

REACTOR RESTRICTED

EARTH FAULT

PROTECTION.

PRESENTLY

NUMERICAL

DIFFERENTIAL RELAYS

HAVING IN BUILT

FUNCTION OF 2 REF OR

2 SEF PROTECTIONS.

(16)

3

3 LINE REACTOR REF PROTECTION

(NGR IS AVAIALBLE) R-CT HV BUSHING CT CORE-2 CTR: 200/1A CLASS: PS NGR-CT EARTH BUSHING CT CORE-2 CTR: 200/1A CLASS: PS

C

E

DISPLAY

ACTIVE START TRIP

RET 670

NORMALLY

HIGH IMPEDENCE

VOLTAGE/CURRENT

OPERATED SINGLE

POLE RELAY IS USED

FOR BUS / LINE

REACTOR RESTRICTED

EARTH FAULT

PROTECTION.

PRESENTLY

NUMERICAL

DIFFERENTIAL RELAYS

HAVING IN BUILT

FUNCTION OF 2 REF OR

2 SEF PROTECTIONS.

(17)

3

3 LINE REACTOR 2 NOs REF PROTECTIONS

(NGR IS AVAIALBLE) R-CT HV BUSHING CT CORE-2 CTR: 200/1A CLASS: PS R-CT STAR BUSHING CT CORE-4 CTR: 200/1A CLASS: PS

3 3 3

1S2 1S2 1S2 1S1 1S1 1S1 P1 P1 P1 CT MB

C

E

DISPLAY

ACTIVE START TRIP

RET 670

P2 P2 P2

3 3 3

2S1 2S1 2S1 2S2 2S2 2S2 P2 P2 P2 CT MB P1 P1 P1 NORMALLY HIGH IMPEDENCE VOLTAGE/CURRENT OPERATED SINGLE POLE RELAY IS USED

FOR BUS / LINE REACTOR RESTRICTED EARTH FAULT

PROTECTION.

PRESENTLY NUMERICAL DIFFERENTIAL RELAYS HAVING

IN BUILT FUNCTION OF 2 REF OR 2 SEF PROTECTIONS.

NGR-CT BUSHING CT CORE - 1 & 2

CTR: 200/1A

(18)

C

E

DISPLAY

ACTIVE START TRIP

REL 670

3

IR3 / A311 IY3 / A331 IB3 / A351 IN3 / A371 3S2 3S2 3S2 3S1 3S1 3S1 P2 P2 P2 CT MB VR11 / E111 VY11 / E131 VB11 / E151 VN11 / E171

LINE/BUS REACTOR B/U IMPEDANCE PROTECTION

R-CT HV BUSHING CT CORE-3 CTR: 200/1A CLASS: PS CVT SELECTION BUS-1 CVT / BUS-2 CVT / LINE CVT CORE-1 VA : 200 CLASS: 3P

(19)

LINE REACTOR PROTECTION FOR LINE

(MAIN-1 PROTECTION)

C

E

DISPLAY

ACTIVE START TRIP

REL 521

3

IR5 / A511 IY5 / A531 IB5 / A551 IN5 / A571 1-CT CORE-5 CTR: 2000-1000-500/1A CLASS: PS 2-BCT CORE-5 CTR: 2000-1000-500/1A CLASS: PS 5S4 5S4 5S4 5S2 5S2 5S2 P2 P2 P2 CT MB P2 P2 P2 5S4 5S4 5S4 5S2 5S2 5S2 VR11 / E111 VY11 / E131 VB11 / E151 VN11 / E171 1-CVT CORE – 1 200VA CLASS: 3P

3

LR-CT 400KV CORE-5 CTR: 2000-1000-500/1A CLASS: PS P1 P1 P1 5S2 5S2 5S2 5S4 5S4 5S4

(20)

LINE REACTOR PROTECTION FOR LINE

(MAIN-2 PROTECTION)

C

E

DISPLAY

ACTIVE START TRIP

REL 316

3

IR4 / A411 IY4 / A431 IB4 / A451 IN4 / A471 1-CT CORE-4 CTR: 2000-1000-500/1A CLASS: PS 2-BCT CORE-4 CTR: 2000-1000-500/1A CLASS: PS 4S4 4S4 4S4 4S2 4S2 4S2 P2 P2 P2 CT MB P2 P2 P2 4S4 4S4 4S4 4S2 4S2 4S2 VR21 / E211 VY21 / E231 VB21 / E251 VN21 / E271 1-CVT CORE – 2 200VA CLASS: 3P

3

LR-CT 400KV CORE-4 CTR: 2000-1000-500/1A CLASS: PS P1 P1 P1 4S2 4S2 4S2 4S4 4S4 4S4

(21)

BUS REACTOR TEED-1 PROTECTION

{BAY3&2}

C

E

DISPLAY

ACTIVE START TRIP

RET 670

3

3-CT CORE-5 CTR: 2000-1000-500/1A CLASS: PS BR-LCT CORE-5 CTR: 2000-1000-500/1A CLASS: PS P2 P2 P2 P1 P1 P1

3

2-CT CORE-1 CTR: 2000-1000-500/1A CLASS: PS P1 P1 P1 P2 P2 P2 P1 P1 P1 P2 P2 P2 5S4 5S4 5S4 5S2 5S2 5S2 1S4 1S4 1S4 1S2 1S2 1S2 4S4 4S4 4S4 4S2

4S2 4S2 IT WORKS ON CIRCULATING CURRENT PRINCIPLE AND IT IS

HIGH IMPEDENCE DIFFERENTIAL RELAY. TEED-1 PROTECTION FOR BAY 2&3 AND THE FOLLOWING CTs & CORES ARE USED 3-CT(CORE-5), 2-CT(CORE-1) & BR-CT (CORE-5) ARE STARRED AND CONNECTED TO TEED-1 PROTECTION

IR5

IY5

IB5

IN5

IR5

IY5

IB5

IN5

IR1

IY1

IB1

IN1

(22)

BUS REACTOR TEED-2 PROTECTION

{BAY3&2}

3

3-CT CORE-4 CTR: 2000-1000-500/1A CLASS: PS BR-CT CORE-4 CTR: 2000-1000-500/1A CLASS: PS 4S4 4S4 4S4 4S2 4S2 4S2 P2 P2 P2 CT MB CT MB P2 P2 P2 4S2 4S2 4S2 4S4 4S4 4S4

3 3 3

2-CT CORE-2 CTR: 2000-1000-500/1A CLASS: PS 2S2 2S2 2S2 2S4 2S4 2S4 P2 P2 P2 CT MB

C

E

DISPLAY

ACTIVE START TRIP

RET 670

RAICA

LBB/BFR

RAICA

LBB/BFR

IT WORKS ON KIRCHOFF’S CURRENT PRINCIPLE & IT IS PERCENTAGE BIASED LOW IMPEDENCE DIFFERENTIAL RELAY. TEED-2 PROTECTION FOR BAY 2&3 IS THE

FOLLOWING CTs & CORES ARE USED. 3-CT(CORE-4), 2-CT(CORE-2) & BR-CT

(CORE-4) ARE CONNECTED TO TEED-2 PROTECTION.

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OVER EXCITATION/FLUX RELAY

{FOR LINE & BUS REACTORS}

RATUB

V/F RELAY

LINE

RATUB

V/F RELAY

BUS

CVT SELECTION BUS-1 CVT / BUS-2 CVT / LINE CVT CORE-1 VA : 200 CLASS: 3P VOLTAGE SELECTION BUS-1 PT / BUS-2 PT CORE-1 VA : 200 CLASS: 3P

(24)

3

IR2 / D211 IY2 / D231 IB2 / D251 IN2 / D271 R-CT STAR BUSHING CT CORE-2 CTR: 200/1A CLASS: 0.2 2S2 2S2 2S2 2S1 2S1 2S1 P2 P2 P2 CT MB VR31 / E311 VY31 / E331 VB31 / E351 VN31 / E371 BASED ON SELECTION

LINE CVT / BUS-1 CVT / BUS-2 CVT CORE – 3

100VA CLASS: 0.2

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CARRIER INTERTRIPPING OF LINE SHUNT REACTOR

LINE SHUNT REACTOR PROTECTION TRIPPINGS WILL BE USED AS DIRECT TRIPPINGS OF LINE IN ADDITION TO OTHER TRIPPINGS. BUS SHUNT REACTOR NEED NOT REQUIRE CARRIER INTER TRIPPING FACILITY.

87R REACTOR DIFFERENTIAL RELAY 21R REACTOR IMPEDENCE RELAY

64R RESTRICTED EARTH FAULT RELAY

ABB

NSD 50

DC +VE FROM PANEL

G4AD V9LC 2

DC –VE FROM PANEL

G4AD V9LC 1

LINE PROTECTION

COUPLER PANEL-1

ABB

NSD 50

DC +VE FROM PANEL

G4AD V9LC 2

DC –VE FROM PANEL

G4AD V9LC 1

LINE PROTECTION

COUPLER PANEL-2

RET 670 REL 670 RET 670

REACTORS INTERNAL FAULTS

87R REACTOR DIFFERENTIAL RELAY 21R REACTOR IMPEDENCE RELAY

64R RESTRICTED EARTH FAULT RELAY

REACTORS INTERNAL FAULTS GROUP-1/A TRIPPINGS

GROUP-2/B TRIPPINGS RET 670

REL 670 RET 670