As for frequent tripping of circuit breaker due to imbalance voltage of 10 kV II-IC 324#、II-3C 330# capacitor bay at 220 kV Ying Feng Qiao substation

the capacitance on the capacitor bank is measured

and individual capacitance measurement is carried out on the phase of capacitor exceeding the rated value.It is found by the result: the capacitance value over the rating results in the secondary imbalance voltage of discharge coil rising to 7.56 V

which exceeding the protection fixed value（3 V） and leading to alarm.The capacitor with disqualified capacitance shall be replaced to keep three-phase capacitance balance and to eliminate imbalance voltage.