On EHV lines, during re energisation (specially in auto reclose operations), heavy switching transients are generated. However, they must be controlled as SIWL level is around 2.5 pu.
Ciruit breakers, for voltages of 400kV or above, for line circuits are equipped with Pre Insertion Resistors to limit the magnitude and effect of switching overvoltages to within permissible limits.
They also help in bringing down the probability of breaker restriking.
circuit breaker
Re: circuit breaker
