In case of switching capacitor bank by high voltage vacuum circuit breaker

reignition over voltage due to reignition of the circuit breaker causes insulation damage between poles of capacitor and even breakdown. In view of the fault circumstance of 35 kV shunt capacitor device and the damage of the capacitor of certain 220 kV substation and also in combination with the fault recording diagrams

switching of the vacuum circuit breaker and the setting of the protection value

it is defined by analysis that the cause for this fault is due to the re-strike over voltage of the high voltage vacuum circuit breaker during switching the capacitor device

which leads to insulation damage between poles of the capacitor. As for accident damage of the capacitor this time

the corresponding measures and suggestions from such aspects as equipment selection and protection setting of the shunt capacitor device are proposed for the reference of on-site operation and maintenance personnel.