Stepping Development of 6-m Long-Gap Discharge Produced by Standard Switching Impulse

A switching overvoltage discharge experiment was conducted on a simulated tower head. The gap spacings among the six-multiple conductor, the cross arm, and the tower were 6.07 m, respectively. The discharge development driven by a 250/2500-μs standard switching impulse was captured by a high-speed camera. The images show that the discharge path presents a stepping mode, and only one streamer guides the leader development. The discharge forms a snake-like route. Each segment of the stepping development is with a length of 1-3.5 m, and the observed curve angle ranges from 40° to 60°.