Experimental study of streamer inception and transition characteristics for live working gap under switching impulse

The switching impulse discharge characteristics are the basis for determining the minimum approach distance in equipotential live working (EPLW) gap. The discharge mechanism of the EPLW gap is not fully deterministic currently. In this study, two actual EPLW gaps and two simplified gaps including sphere–plane gap and bundle conductor + rod-plane gap are established, and the discharge mechanism of these gaps is investigated. The result indicates that the discharge characteristics of sim-worker's back and feet are similar to the simplified electrode. For the sim-worker's back, the streamer inception time delay, inception voltage, injected charge, and transition time are 93.3 μs, 765 kV, 6.19 μC, and 44.7 μs, respectively. The current waveforms of the sim-worker's back and the sphere electrode (R = 0.3 m) exhibit similar characteristics, both containing single pulse, and streamer length nearly half the gap. For the sim-worker's feet, the corresponding values are 28.5 μs, 307 kV, 0.67 μC, and 81.6 μs, similar to the bundle conductor + rod electrode (R = 5 cm), with multiple pulse current waveforms and streamer length of 0.49 m, also similar to the bundle conductor + rod electrode (R = 5 cm). The result can contribute to lineman safety protection and simplified gap design for live working.