The study of the discharge mechanism and characteristics of micro-voids in the solid dielectric

The insulation breakdown caused by micro-voids discharge in solid dielectrics is one of the main causes of insulation failure of the electrical equipment. The concentration of electric field arose from micro-voids can´t be measured from the outside directly, so the theoretical calculation is of great significance to the equipment insulation design, the work requirements of the electric field and fault detection. On the basis of nonlinear transient multi-coupled computational model, this paper studies the impact of the size, the location, the number of the micro-voids and the space charge on the discharge process. The size of the micro-void that is the easiest to discharge is determined. The temperature of the dielectric and the micro-voids will rise after discharging, resulting in the increasing of the conductivity and the mobility of the space charge both of which affect the electric field distribution in turn. So the distribution of the temperature is also analyzed in this paper.