Trap Distribution and Flashover Characteristics of Carbon-Black-Filled EPDM in Low Temperature

The power leading insulation of high-temperature superconductivity (HTS) equipment has to confront the electric field concentration and huge temperature differential, which puts forward higher requirements for insulation materials. Surface flashover will lead to the failure of the power leading insulation. Ethylene propylene diene terpolymer (EPDM) has been proved to be a potential application in HTS power leading insulation. Doping of carbon black (CB) nanoparticles into EPDM can improve the polymer insulating properties for HTS equipment. However, the effects of low temperature on flashover as well as the correlated trap distribution of CB-filled EPDM have not been completely researched. In this paper, the samples were prepared by mixing CB nanoparticles into EPDM with the content of 0, 1, 3, and 5 wt%. The depolarization current was measured to estimate the trap characteristics of the nanocomposites at the temperatures of 193, 243, and 293 K. Needle-plate flashover experiments were performed at the same condition. Obtained results indicate that low temperature will change the effect of nanoparticles doping on the depolarization current and trap distribution. The surface flashover strength is significantly promoted by CB nanoparticle doping, which has strong correlation with the trap characteristics.