Various Generator protection Schemes, ,generator protection ,rotor faults ,stator faults ,low impedance grounding ,high impedance grounding ,field ground fault protection ,negative sequence time overcurrent relay ,generator capability curve

4.  ROTOR ELECTRICAL FAULTS
 LOSS OF EXCITATION
 LOSS OF SYNCHRONISM
 FAILURE OF PRIME MOVER
 LUBRICATION OIL FAILURE
 OVER SPEEDING
 CORE LAMINATION FAILURE

5.  STATOR ELECTRICAL FAULTS
 OVER LOADS
 OVER VOLTAGE
 UN BALANCED LOADING
 OVER FLUXING

6. 6
BASIC SYNCHRONOUS GENERATOR
GENERATOR PROTECTION

7. 7
1.ARMATURE WINDING- STATOR
2.FIELD WINDING-ROTOR.
RELATIVE MOTION BETWEEN THESE TWO
WHICH IS ACHIEVED BY THE
3.Prime Mover-TURBINE.

8.  Capacity – 247MVA
 Stator Voltage – 15KV/15.75KV)
 Stator current – 9060 Amps
 Rotor Voltage – 310V
 Rotor Current – 2600Amps.
 Frequency – 50 Hz. Speed –3000RPM

9.  Capacity – 222MVA
 Stator Voltage – 13.8
 Stator current – 9297 Amps
 Rotor Voltage – 336V
 Rotor Current – 2180Amps.
 Frequency – 50 Hz. Speed –136RPM

10. N = 120F/P
N – Rotational Speed RPM
F - Frequency Hz
P – Number of Poles

11. 11
SYNCHRONOUS GENERATOR TYPES
GENERATOR PROTECTION

12. 12
TYPICAL UNIT GENERATOR – TRANSFORMER
CONFIGURATION

13. 13
Device Function
21
Distance Relay. Backup for system
and generator zone phase faults.
24
Volts/Hz protection for generator
over excitation.
32
Reverse power relay. Anti-
motoring protection.
40 Loss-of-field protection.
46
Negative sequence unbalance
current protection for the
generator.
ANSI DEVICE NUMBERS

14. 14
Device Function
49 Stator Thermal Protection.
51GN Time over current ground relay.
51TN Backup for ground faults.
51V
Voltage-controlled or voltage-
restrained time over current
relay. Backup for system and
generator phase faults.
59 Overvoltage protection.
59GN
Overvoltage relay. Stator ground
fault protection for a generator.
ANSI DEVICE NUMBERS

15. 15
Device Function
78 Loss-of-synchronism protection.
81
Frequency relay. Both
underfrequency protection.
86 Hand-reset lockout auxiliary relay.
87G
Differential relay. Primary phase-
fault protection for the generator.
87N Stator ground fault differential .
87T
Differential relay. Primary
protection for the transformer.
87U
Differential relay for overall
generator and transformer
protection.
ANSI DEVICE NUMBERS

16. 16
LOW IMPEDANCE GROUNDING
GENERATOR PROTECTION

17. 17
HIGH IMPEDANCE GROUNDING
GENERATOR PROTECTION

19. 19
NEGATIVE SUENCE RELAYS – BASIC DESIGN

20. 20
GENERATOR CAPABILITY CURVE
LOSS OF FIELD PROTECTION