Non-destructive Condition Assessment of silicone rubber composite insulators

Thanks to its light weight and anti-pollution flashover characteristic, High Temperature Vulcanized (HTV) silicone rubber is now a main component of the housing and shed material of composite insulators, which are widely used in China in recent years. However, as a polymer material, the weathering resistance of composite insulators is an issue worthy of attention for degradation phenomena such as cracking, chalking, color fading etc., were reported in many parts of China. In this paper, more than 30 composite insulators´ shed samples were collected from the power grid of a city located in the northern part of China and a series of tests have been conducted on these samples. Test indexes were divided into into two groups to characterize the operation performance of composite insulators. Color change and hardness were selected as the two key indexes for field engineers to assess the degradation level of composite insulators and the method of hardness and swelling ratio tests were applied to quantify the color change level. Tests results show that these two indexes are precise, convenient and non-destructive.