Dielectric Response of Silicone Rubber Composites for Outdoor Insulation at Elevated Temperatures

Composite insulator has been widely used worldwide, especially in polluted areas and ultra-high voltage systems. However, premature degradation of silicone rubber housing significantly affects the long-term performance, which may be attributed to the internal interface introduced by fillers. Dielectric response is able to characterize the interfacial state, while the temperature involved in previous research is relatively low. As a result, the polarization process stemming from the interface is not prominent enough. Therefore, in this research, the dielectric response of silicone rubber composite over broad ranges of frequency and temperature (up to $200^{\circ} \mathrm{C}$) is investigated. Dissado-Hill model is applied to decouple the overall response, especially at elevated temperatures. The activation of the polarization process originating from ATHmatrix interface is further analyzed, which is dominant at elevated temperatures. The temperature dependence of characteristic frequency is in great consistent with previous results with a better accuracy. Based on the results, dielectric response is a feasible approach to characterize the internal interfacial state qualitatively and quantitatively.