Effects of temperature on the partial discharge characteristics of silicone oil

High voltage cable systems tend to have a higher risk of insulation failure at joints and terminations than the main body. One of the insulating liquids used in cable sealing end (CSE) is silicone oil. Increase in temperature is known to affect the physical and dielectric properties of insulation materials. This study investigates the partial discharge characteristics of a silicone oil at different temperatures from 20 °C to 80 °C. The sample used in this study is a high-viscosity silicone oil, which has a dynamic viscosity of 13,000 cP at 20 °C. From the PD measurements obtained, it showed that partial discharge inception voltages (PDIV) are comparable at different temperatures. The PD magnitude showed consistent results at various temperatures indicating insignificant effect of temperature on the PD magnitude. On the other hand, PD repetition rate decreased with the increase of temperature where the PD repetition rate at 80 °C is 30% lower than that at 20 °C at applied voltage of 45 kV.