From the above Table-I, it may be observed that SIL of 1200kV AC system is about 6030MW which is about 2½ times SIL of 765kV system and 11½ times SIL of 400kV system. With development of 1200kV Transmission network, the ROW can be optimized.
B. Insulation Co-ordination of 1200KV AC System
1) Switching Over Voltage:
Common practice in long EHV system for controlling switching over voltages during any switching operation is to equip circuit breaker with pre-insertion resistor (PIR) which