Space Charge Accumulation in Silicone Rubber Influenced by Poole-Frenkel Effect

Abstract

With the rapid increase of electrical energy consumption in metropolises, more and more power cables are utilized in power grid or urban power network to transmit and distribute electrical energy. Silicone rubber is widely used as polymeric insulating materials of power cable accessories due to their excellent electrical and thermal performances. However, under high dc electric field space charges can accumulate inside the silicone rubber, which will distort the electric field in the bulk of the material, influencing the reliability and safety of operation. A bipolar charge injection and transport model is adopted to investigate the accumulation of space charges and distortion of electric field in silicone rubber. It is found that when charge injection rate is higher than the charge migration rate, space charges will accumulate in the material and the accumulation increases with an increase in electric field. The influence of the Poole-Frenkel effect is then studied. It is found that stronger Poole-Frenkel effect can enhance the nonlinearity of effective carrier mobility of silicone rubber, reducing the accumulation of space charges. This indicates that tuning the nonlinearity of effective carrier mobility by nano-doping can suppress space charges, improving the reliability of power cable accessories.