Surface Flashover Phenomenon Under 180-ns Quasi-Square Wave With Voltage of Several Hundred Kilovolts

Experiments on the surface flashover under 180-ns quasi-square waves with voltage of several hundred kilovolts are reported. In the experiments, employing a 280-kV 180-ns full-width at half-maximum (FWHM) voltage on the load, no flashover occurred. When the voltage was up to 350 kV, even 420 kV, surface flashover along the insulator occurred, and it started at the top part of the applied voltage pulse, so the FWHM of the output voltage of pulse generator was reduced to 150 ns, even 120 ns. Also, the experiment results show that surface flashover channel could be recovered quickly if a heteropolarity voltage was applied on the flashover channel. Finally, the characteristics of the surface flashover are present, including the flashover time, flashover current, and resistance.