Kinetics of the thermal breakdown of dielectrics

The kinetics of thermal breakdown of a dielectric is investigated by the computer simulation method using the two-dimensional model of a dielectric with heterogeneous structure. The material is assumed to be placed in an external homogeneous electric field and is divided into the cells of different local electric field strength. The output, redistribution, and dissipation of heat from the cells are taken into consideration. It is supposed that overheating of a cell leads to its destruction, and the breakdown takes place when two electrodes are joined together by a continuous chain of damaged cells. The correlation between the damage kinetics and the dependence of the average temperature of a dielectric on time is found. The equation connecting the breakdown time, material properties, and operating conditions is suggested.