Mechanism and quantitative characterization of color fading phenomenon of HTV composite insulators silicone rubber

The silicone rubber of composite insulator is a kind of polymer organic material, as a result of the environmental stress under long-term operating. The performance of insulators directly affects the safe operation of the transmission lines. The aging of silicone rubber is related to not only the complex operating environment, but also the aging resistance ability. In China, High Temperature Vulcanized (HTV) silicone rubber is applied to manufacture the sheds and sheath of composite insulators for decades. Hardening and color fading are two significant aging phenomena in most cases. The aim of this paper is to study the color fading mechanism of HTV silicone rubber and develop a method to quantify its color fading degree for field application. In this paper, 18 composite insulator specimens are collected and analyzed. Test results show that there is a positive correlation between color fading and silicone rubber's microstructural change. As a result, a quantitative measuring method of silicone rubber's color fading degree has been developed from this study, which could be applied in field tests to help field engineers to decide the aging level of composite insulators.