Study on Breakdown of HTV Silicone Rubber After Water Invasion

Decay-Like fracture of composite insulators had become a problem that has plagued the operating department in recent years. People had found that there were perforations on the silicone rubber house of the Decay-Like fracture insulators. It was speculated that the breakdown of the silicone rubber house during operation was the cause of perforation. The effect of water invasion on the breakdown characteristics of HTV silicone rubber was studied in this paper. Firstly, the water absorption test was carried out on HTV silicone rubber, and the water absorption characteristics of the material based on the Langmuir diffusion model were obtained. The change law of the content of free water and bound water during the water absorption process were studied. Secondly, we measured the breakdown voltage of silicone rubber under different water absorption degrees, and the relationship between free water content, as well as bound water, and the breakdown voltage of silicone rubber was obtained, respectively. We found that the free water content in the silicone rubber has a good correspondence with the breakdown voltage. We proposed that the breakdown voltage drop of HTV silicone rubber was caused by the formation of a water bridge under electric field.