Partial discharge inception and degradation characteristics of inverter-fed motor sample under surge voltage condition

Surge voltages with the rise time of the order of nano-seconds may cause partial discharge (PD) and result in the degradation of electrical insulation performance of the inverter-fed motor coils. We investigated the PD inception and degradation characteristics of twisted pair samples under surge voltage condition. Experimental results firstly revealed that there existed no obvious correlation between PD inception voltage (PDIV) and the rise time of surge voltage. Secondly, PD propagation and degradation characteristics were also investigated under the higher voltage application, and discussed in terms of charge behavior in air gap and on enamel surface. Finally, we obtained the dependence of time leading to BD on enamel coating thickness of the wire.