Mitigation of current restrict of MV circuit breakers in shunt capacitor by metal oxide arrester

The Medium-voltage (MV) circuit breakers can fail to interrupt three-phase fault currents when power systems have transient recovery voltage (TRV) characteristics which exceed the rating of the circuit breaker. Surge arresters protect equipment of transmission and distribution systems. Arresters installed today are all metal-oxide (MO) arresters without gaps. This paper presents the application of MO surge arresters as a switching overvoltage protection of capacitor bank Medium-voltage circuit breakers. Based on an existing MV-Capacitor bank on PSCAD-EMTDC , the simulation is performed to show the effectiveness of the surge arrester in reducing circuit breaker TRVs and in minimizing the probability of circuit breaker restricts. The energy requirements of the surge arresters and the overvoltage protection levels of the capacitors for different surge arrester arrangements are calculated.