Analysis of failure of a circuit breaker employed for capacitor switching: A review

It is common practice to install shunt capacitors to improve the power factor and voltage profile at all voltage levels in the power system. Almost all type of load including domestic user's appliances is inductive. Due to low water level agricultural load are also increasing. All these conditions lead to poor power factor and large amount of reactive power flows through the transmission line and voltage drop occurs. Hence, in several areas low voltage pockets are created. To improve this low power factor, adequate compensation is to be provided at load end point. Due to increasing load/consumers it is very difficult to insist every consumer to provide compensating device. Ultimately power transmission companies have decided to provide the capacitor bank at the feeding substation at various voltage levels such as 11KV, 33KV and EHV levels also. And now a day it is well accepted practice to install a capacitor bank at the feeding substation for improving the power factor of the system. The major problem with the capacitor bank is the interrupter failure i.e. the failure of circuit breaker employed for its switching. It is reported by power distribution and transmission companies that breaker failure occurs before its specified number of operation. In order to understand this problem, I thought of taking a topic of dissertation work which relates to the failure of circuit breaker employed for capacitor switching.