Discrimination of partial discharge type in SF/sub 6/ gas by simultaneous measurement of current waveform and light emission

An attempt was made to give experimental evidence for partial discharge (PD) physical models where the discharge type changes from streamer to leader while PDs are taking place to breakdown in SF/sub 6/ gas. The authors investigated the fundamental phase-resolved PD characteristics as well as the light emission characteristics of PD as a function of AC applied voltage and SF/sub 6/ gas pressure. The results of the light emission revealed that two kinds of luminous types, sphere like and filamentary brightness PDs, appear depending on AC applied voltage and SF/sub 6/ gas pressure. By introducing the simultaneous measuring technique of a single PD current pulse waveform and light emission at around the positive peak of the applied AC voltage, one can identify the two types of PD, streamer and leader.