Effect of Temperature and Humidity on the Surface Charge Decay of Silicone Rubber

This paper focuses on the silicone rubber insulator widely used in HVDC (High Voltage Direct Current) system. In the process of using, the insulation of silicone rubber insulator is affected by different environmental factors. So this paper focuses on temperature and relative humidity's influence on the surface charge decay and take a systematical study. As for the experiment, after charging by needle-plate electrode, the potential distribution on the surface of silicone rubber was measured by the two axis measuring platform. Then the surface charge distribution was obtained by surface charge calculation algorithm of the translation invariant system. This paper gives the surface charge distribution under different temperatures from 10 to 50 degrees centigrade and different relative humidity from 10 to 90 percent by dissipating for an hour. At the same time, through the analysis of the surface charge distribution, the surface potential decay curve and the measurement results of insulator trap energy level, which can present the surface charge's dominant decay path, it was found that the higher the temperature especially over 50 degrees centigrade, the higher the relative humidity, the faster the surface charge decays. And the surface charge mainly decays through the volume conductivity at low humidity. At high humidity, the surface charge decays mainly along the surface. Especially, when the relative humidity increases to 60%, the dominant path of surface charge decay has changed. The conclusions in this paper can provide guidance for safe operation of insulator.