Dielectric Strength and Space Charge of Ethylene Propylene Rubber under Different Pre-stress

In order to find out the influence mechanism of the space charge distribution characteristics on the dielectric strength of ethylene propylene rubber (EPR), the space charge distribution of EPR at different electric field and temperatures was measured by pulse electroacoustic technique in the paper. AC and negative DC dielectric strength of EPR under different pre-stress conditions was measured. The results were analyzed by the WEIBULL theory. Combined with the avalanche breakdown theory and the space charge packet migration characteristics, the relationship of space charge and dielectric strength of EPR was investigated. The experimental results show that the breakdown process of EPR depends on the polarity and magnitude of pre-stress which closely relates to space charge distribution.