Generator Data

Direct Axis Tran Reactance Xd´=20.8%Direct Axis Syn Reactance Xs = 182.5%

Rated MVA = 247

Rated Voltage = 15.75kVRated Amp = 9054A ,SCR:0.586

GT

UATG

ener

a to r

GT Rated MVA = 250MVAImpedance 14% ,420/15.75kVRated voltage 400kV,Ynd1Fault MVA 40kA (27712MVA)

UAT rated MVA 16MVARated voltage 15.75/6.9kVImpedance 7%,Dyn11

GEN

R

Generator & Out-Line Equipments

GT YNd1

UAT

GEN

NGT

CB122 3

4

ISO-D

ISO-A

ISO-B

ISO-C

M1

M2

TRCB

CB

UNIT BUS

UNIT BUS

CT500/ 1

CT-3600 / 510000 / 5

CT-3CT-310000 / 5

CT- 3

NCT 150 / 1

7

6

CT-3

CT-31600/11600 / 5

11 NCT400/ 1

Gen-PT-3

8

9. 95400A 10sec

9

NCT1600 / 5

NCT200/11600 / 5

NGR

NGR

15.75 kV/ 240V75 KVA

NGR0. 456340A 5min

BUS

1

GRP

Bus-PT-3

GCB

FBOPEN

UATC/O

GCBOPEN

A / B / A / B / C

BOILER TRIP A TURBINE

TRIPA / B

TURBINE

TRIP

10

BCT400/1

5

10000/5

100% Stator E/F &Inter-turn Fault

Dyn11

GCB OPEN & TLR operated

LA

List of Relays for Generator Protection

NO NAME OF RELAY PURPOSE ACTION

1 DIFFERENTIAL PROT. (87G) PROTECTION TRIPPING , CLASS-A

2 100% STATOR E/F (64G) PROTECTION TRIPPING, CLASS-A

3 ROTOR EARTH FAULT (64R) PROTECTION TRIPPING, CLASS-A

4 INTER-TURN FAULT (95G) PROTECTION TRIPPING, CLASS-A

5 STATOR BACK UP E/F (51NG) PROTECTION TRIPPING, CLASS-A

6 LOCAL BKR. BACKUP (50Z) PROTECTION TRIPPING, CLASS-A

7 BACKUP IMPD PRE-SYN (21G1) PROTECTION TRIPPING, CLASS-A

8 BACKUP IMP. POST-SYN (21G2) PROTECTION TRIPPING, CLASS-A

9 OVER VOLT. STAGE-1 (59G1) PROTECTION AVR AUTO C/O MAN CH

10 OVER VOLT. STAGE-2 (59G2) PROTECTION TRIPPING, CLASS-A

11 LOW FORWARD POWER (37G) PROTECTION TRIPPING, CLASS-C

12 REVERSE POWER (32G) PROTECTION TRIPPING, CLASS-B

13 OVER FREQUENCY (81F2) PROTECTION TRIPPING, CLASS-B

14 FIELD FAILURE (40G) PROTECTION TRIPPING, CLASS-B

15 UNDER FREQUENCY,(81F1) PROTECTION TRIPPING, CLASS-C

16 THERMAL OVERLOAD (51GTh) PROTECTION TRIPPING, CLASS-C

17 NEGATIVE PH SEQUENCE(46G) PROTECTION TRIPPING, CLASS-C

18 POLE SLIPPING (78G) PROTECTION TRIPPING, CLASS-C

19 CHECK SYNCHRONISING (25G) PROTECTION CLOSING PERMISSIVE

CLASS-A MFR,TLR & GEN CKT. BKR.OPEN, CLASS-B TLR,GEN CKT BKR OPEN, CLASS-CGEN CKT BKR

Generator Differential Relay(87G)

GEN GT

87 Class-A TripIop=10%

Stab. Res

CT-2 CT-3

Generator Stator Earth Fault(64G)

GEN GT

N Dis Unit & 3rd Her Unit

Generator Winding

Blnd Zone

N L3rd Her UnitNeutral Dis

Unit

Class-A Trip with tdPVMM163

V3

VN3

VL3

VL3

VN3

Slop

e m

1

Slope m2

Generator Rotor Earth Fault(64R)

Gen Fld Wndg

Main Exct

Resistance

Rotor E/F Relay

Class –A Trip

DC

Meas.volt Um

50V+/-

<80kOhm –Alarm & <5kOhm-Trip

Generator Field Failure Relay(40G)

GEN

40GClass-B Trip with td 2.0 Sec

-X

Z1=1.5Ohm

Z2=25.9Ohm

+R

Syn Gen.

Ind.Gen

Load

Loss of Field

U/V (<75%) Class-B Trip Inst.

CT-2

Generator Low Forward Power Relay(37G)

GEN

37G

Power Flow

GT

UAT

UAT

GCB

Class-C Trip TLRFB Close

TLR Reset

Blocking

CT-2

Generator Reverse Power Relay(32G)

GEN GT

32G

UAT

UAT

GCB

TLR Class-C Trip with Td 2.5 Sec

Power Flow

Class-B Trip with Td 5.0 Sec

Setting: 0.5%Pn

Ch. Angle: 90Deg

VBY

VR

VYVB

IRIV θ

)

CT-2

Generator Under Frequency Relay(81F1)

GEN

Class-C Trip with Td 2.5 Sec

81G1

Generator Over Frequency Relay(81F2)

GEN

Class-B Trip with Td 2.5 Sec

81G2

Generator Pole Slipping relay(ZTO)

GEN

78GClass-C Trip

75deg

Load AreaSource

Area+R

X

Dir. Unit (A)

Blinder Unit (B)

Ope

ratin

g .Z

one

R

Locus of Pole Slip

Typical Power Swing Locus

40msT

CT-2

Generator Negative Phase Seq.(RARIB)

GEN

46G

Class-C Trip Start of time measure at (8% of Im)

0.1

1.0

10

100

1000

10 100 250Insc

(t/K)

5005

K=8

Operating Curve

CT-2

Generator Over voltage(Stage-I)59G1

GEN

59G1AVR Change over from Auto to Man

Setting 110% 2.0Sec

Generator Over voltage(Stage-II)59G2

GEN

59G2

Setting 120% 1.0Sec

Class-A Trip

Generator Over current Relay(51G)

GEN

51GAlarm only

CT-2

Generator Thermal Over Load(51Gth)

GEN

51GthClass C Trip

Thermal current setting=0.92XIn

Heating Time constant TH =1min

t=THln(Ieq/Is)²

(Ieq/Is)²-1.0609CT-2

Generator Intern Fault Protection(95G)

95G

NGR

IVT 110/80v

IVT 25.4/110v

R

Y

B

PT Supply

Setting 7.5v0.456

Generator Stator Backup Earth Fault(51NG)

Class-A TripN Dis Unit

GEN GT

51NG

NGR

0.456ohm

0.456 /300A

150/1 A

15.75kV/240V,75kVA

Generator LBB Protection (50Z)

GEN GT

GCB

50Z

UAT

UAT

Class-A Trip with td

+ ve Trip relay

Optd (86)

CT-1

Generator Check-Syn. Relay(25)

GEN GT

CHK. SYN. RELAY

EHV BUS

GEN PT

(VR-Y)

BUS PT

(VR-N)

YNd1

VR-N

R

YB

R

Y

BN

T=1/(fR-fI)

VR

VI

VR

VI

V

t

P

21G1 Gen Backup Impd. Relay(Pre-Syn)

GEN GT

21G1Class-A Trip with td

GCB

GCB OFF

14.24%UAT

UAT

7%

Reverse Reach 25%

of Frd

16%

Z=1.5ohm Td=0.5s

CT-2

21G2 Gen Backup Impd. Relay (Post-Synchronize)

GEN GT

21G121G2

GCB

Class-A Trip with td

IBT 12%

Reverse Reach 25%

of Frd

UAT

UAT

UAT

Z=1.68ohm Td=2.0s

CT-3