Dielectric Strength of Ethylene Propylene Rubber under Thermal and Mechanical Stress

In order to find out the effect of temperature and mechanical stress on the dielectric breakdown strength of Ethylene Propylene Rubber (EPR), AC breakdown tests of EPR samples were carried out at different temperatures and compressive stress. Two-parameter Weibull statistical distribution was used to analyze the breakdown strength. The experimental results show that the dielectric strength of EPR decreases with the increase of temperature when only temperature is applied. Under the same temperature, the breakdown strength of EPR firstly increases with the compressive stress rising, gradually reaches a maximum and finally shows a decreasing tendency. It's due to the effect of compressive stress on the intermolecular distance and thermal expansion of EPR.