Effect of dielectric surfaces on the nature of partial discharges

A mathematical model for a short gap breakdown in air was employed to examine the nature of the initiating discharge on the dielectric surface of a dielectric/metallic electrode gap of 0.500 mm separation in a uniform electric field at atmospheric pressure. The calculations demonstrate that in the absence of field enhancing surface asperities, the incipient discharge, occurring on a dielectric surface, exhibits the pronounced breakdown channel expansion characteristic of pulseless glow discharges