An explosion accident of a 40.5 kV circuit breaker for switching current-limiting reactor is analyzed.Through spot inspection

fault signal analysis and dissection of the fault breaker

the accident process is inferred.It is determined that rupture of the elastic cylindrical pin connecting the shaft and the inner connecting lever is the direct cause of the accident.The waveform from switching stroke property test of the same type of the circuit breaker indicates that the poor performance of the bumper is the essential cause of the accident.