Performance of insulators treated with semiconductive silicone rubber coating during fog and polluted conditions

Ice accumulation on insulator surface imposes serious problems on power systems. One approach is to develop a hydrophobic coating with semiconducting characteristic resulting in heat generation, which is only coated on the bottom side. This paper focuses on the performance of the insulators treated with semiconductive coating during fog and pollution conditions. Three kinds of samples were tested, including insulator without any coating, insulator coated with normal RTV coatings and the one with semiconductive coatings. The artificial pollution tests were carried out in a fog chamber. The leakage current and the flashover voltage during the fog and polluted conditions were investigated. FEM calculation was also used to help understand the anti-contaminate performance. Test results indicate that the pollution flashover voltage of the semiconductive ones is almost twice of the pure ones, but a little lower than the RTV ones. The primary causes of high pollution flashover voltage are the joint action of the hydrophobicity of the coating and the drying effect generated by the leakage current.