An Investigation on Discharge Fault of Outdoor Oil-Filled Cable Terminal at Low Temperature

Recently, there have been many accidents in oil-filled cable terminals, which are closely related to the low-temperature extreme weather (as low as −30°C). Preliminary analysis believes that the solidification of silicone oil is the principal cause. In order to explore the mechanism of accidents, the partial discharge experiments, silicone oil solidification process observation, and electric field simulation were studied to investigate the impact of silicone oil states on the electrical performance of cable terminals. The results show that, under low-temperature, silicone oil will undergo obvious solidification and shrinkage, causing the interface defects to expose again. The maximum distortion field strength value reaches 6.48 kV/mm which is significantly promotes partial discharge. Therefore, silicone oil phase change will have an irreversible effect on the interface insulation of the cable terminal.