Space charge evolution and its effects on electrical tree degradation in silicone rubber at varied temperature under polarity reversal voltage

Electrical tree is one of the main reasons for cable failure. In this paper, the space charge evolution and electrical tree characteristics under polarity reversal voltage with varied temperature in silicone rubber (SIR) are carried out. Results show that as temperature rises from 30 °C to 120 °C, electrical tree initiation voltage declines by 17.8%. Meanwhile, the trees become denser, and the tree length is larger correspondingly. In order to ascertain the charge transportation and its influence on tree initiation process under polarity reversal voltage, we build a bipolar carrier transportation model with needle-plate electrode. Space charge transportation characteristics and corresponding electric field are simulated. Moreover, the evolution model of electrical tree under polarity reversal voltage is discussed. The presence of homo space charge leads electric field to become larger during the voltage reversal process. The segment relaxation of SIR and more, deeper space charge injection make tree initiate more easily at higher temperature.