Effect of Cryogenic Temperature on Tree Characteristics in Silicone Rubber/SiO2 Nanocomposites Under Repetitive Pulse Voltage

Silicone rubber (SiR) is an important insulating material in high-voltage cable accessories. Electrical tree is a typical electrical aging inside SiR insulation and will cause breakdown when it reaches the ground. The tree characteristics may be changed by the cryogenic temperature because of the changing physicochemical properties. Besides, at temperatures above 273 K, addition of nanoparticles into SiR has been proved to have the effect of improving insulating properties. However, the effect of temperature and nanoparticles from 273 to 77 K under repetitive pulse voltage has not been researched. In this paper, the samples were prepared by mixing nano-SiO2 into liquid SiR and the proportion was set to be 0 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, and 2.0 wt%, respectively. The experiment temperature was set to be 243, 213, 183, and 77 K. Repetitive pulse voltage was employed to generate electrical trees between the needle-plate electrodes. The growing process of electrical tree was recorded by a microscope system and pictures were captured. The experiment results indicated that both the cryogenic temperature and nanoparticles influence the treeing process in SiR/SiO2 nanocomposites.