Detection and characterization of thermal degradation of HTV silicone rubber used in high voltage composite insulator taking into account abnormal temperature heating

Recently, the abnormal temperature heating was observed on some degraded high voltage silicone rubber composite insulator, this phenomena may be caused by the leakage current or inner discharge, this abnormal heating seriously affects the safe and stable operation of the composite insulator, therefore, the detection and characterization of thermal degradation of high temperature vulcanization (HTV) silicone rubber are necessary for maintaining and optimizing the application of HTV silicone rubber. In present research, the thermal degradation test was performed under aerobic conditions, which is consistent with the actual situation. Then, a variety of physical and chemical characterization methods were used to study the characteristics of HTV before and after degradation. Based on these experiments and characterization, the degradation mechanism of HTV silicone rubber under thermal condition was explained and proposed, i.e. as for the matrix, two reciprocal processes, i.e. the broken of siloxane main chain and the oxidative cross-linking of siloxane main chain, occur simultaneously, and as for the ATH filler, thermally decomposition occur. The present work is helpful for better understanding of the thermal degradation behavior of silicone rubber material used in high voltage silicone rubber composite insulator.