Xiangyang Peng

Study of anti-icing performance of insulator strings bottom-coated with semiconductive silicone rubber coating

Prevention of icing flashover on transmission lines has become an important problem. A new method for mitigating effects of glaze ice on energized insulators has been developed. Semiconductive silicone rubber was painted on the bottom of suspension disc insulators, while the upper ceramic surface was untreated. An electrically conductive path was formed when supercooled water or droplets bridged the uncoated areas. The power loss was limited when there was no precipitation. The heat and partial discharge energy generated by the leakage current melted the original ice accretion on the insulator surface. The electrical performance of the insulator string with this kind of coating under freezing rain conditions was comparable with that of a clean insulator string. The impact of the ambient temperature on the anti-icing performance was also evaluated. In addition, the performance of the insulator with bottom surface semiconductive coating under fog conditions was compared with an uncoated string.

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.