Dynamic Characteristics of the Discharge in Short Air-gap with Unsymmetrical Dielectric-covered Electrodes

With the purpose of studying partial discharge in the short-gap of the insulating coordination and deeply understanding kinetic behavior of gas discharge in gas-dielectric insulation, in this paper, the formation reasons and the discharge character of air-gap discharge under unsymmetrical dielectric covered electrodes is numerically investigated on the basis of one-dimensional fluid model. The paper presents results stemming from an analysis of the influences of the applied voltage amplitude, gap distance, as well as dielectric layer thickness on the insulation structure. The simulation results show that the peak values of the discharge current and the electric field are asymmetry in the former and the latter half-cycle, because of the different secondary electron emission coefficients of the metal electrode and the dielectric electrode. In the case of small gap width, multiple current pulses can be formed in each half-cycle of applied voltage. When the applied voltage is fixed, the gap distance and layer thickness can influence the number and the amplitude of current pulses.