Numerical analysis of dielectric breakdown in polypropylene film based on thermal and electronic composite breakdown model

DC electrical breakdown of polypropylene film was studied experimentally and theoretically. The temperature region was divided into two regions, and qualitative analysis of experimental results suggested an electronic breakdown in the low-temperature region and a thermal process in the high-temperature region. A novel breakdown model was proposed by introducing the electronic-breakdown criterion with thickness dependence in the bulk into the thermal-breakdown process due to the transient conduction current. The model could successfully explain the breakdown characteristics, not only in the low temperature, but also in the high-temperature region. This model suggested that the electronic breakdown occurs by hetero space charge at the anode at about 100°C. Experimental results of charging and discharging currents and breakdown tests with different combinations of electrode metals at 100°C supported the prediction of this breakdown model