Page 313 - Practical Power System and Protective Relays Commissioning

Protection Relays Settings Chapter | 19 307

FIGURE 19.6.1 Generator and transformer data.

333 MW xd 5 191% xd 5 33%
0
Xdv 5 22% F 5 50 Hz
2
I 2 5 15% I .t 5 10 S CT 5 13,000/1 22 kV
Power Factor (PF) 5 0.8 S 5 417 MVA
Unit transformer (T 2 )
25/15/15 MVA 22/6.4/6.4 kV
Z% 5 8% at 15 MVA
Generator transformer (T 1 )
420 MVA 225/22 kV Z% 5 14%
Station transformer (T 3 )
25/15/15 MVA
220/6.4/6.4 kV
Z% 5 8.2% at 15 MVA
CTs 5 13,000/1
1. Stator earth fault protection
95% stator earth fault relay (R 1 )
Maximum fault current in neutral 5 20 A
1
I set 5 (1 0.95) 20. 5 0.2 A
5
t to be set to 5 0.05 second.
Tripping action:
1. HV CB of transformer T 1 ;
2. T 2 6.4 kV incoming feeder tripping;
3. Turbine tripping;
4. Generator excitation tripping.