Discrimination technique of streamer and leader type of partial discharge in SF6 gas using UHF method

The relationship between PD current pulse waveform at the PD source and radiated electromagnetic (EM) waveform is investigated, due to a metallic particle in SF₆ gas. Leader discharge with the larger PD charge magnitude and the longer propagation length than those of streamer discharge can be an indicator of breakdown in SF₆ gas. Simultaneous and synchronous measurement of PD current and EM signals in SF₆ gas revealed that the streamer discharge and leader discharge could be discriminated in both time and frequency components, respectively. Compared with the streamer discharge in our experiment, the leader discharge is characterized by the longer rise/fall time. The partial discharge that has relatively little frequency components of 1500 MHz with electromagnetic waves can be presumed a leader discharge. This means that by applying the new technique, the streamer and leader types of PD in SF₆ gas can be discriminated in UHF detecting system.