Analysis on operating performance of RTV coated insulators used in dry area

Room temperature vulcanized (RTV) silicone rubber coating is a type of anti-pollution flashover coating which has been widely used in China. Featuring good hydrophobicity and adhesive property, RTV coatings are applied to insulators to increase the pollution flashover voltage of insulator strings. Shanxi province is a main coal producing area in China where the airborne contaminant is heavy with relatively low humidity and dry climate. In this paper, several macro performance tests were conducted on RTV coated insulators collected from Shanxi province which have been in operation for more than five years. Tests results show that the collected insulators maintain good appearance with no peeling off or color fading phenomena observed. It is also found that the hydrophobicity of RTV coated insulators declines obviously after the surface contaminant is removed and the functional group analysis shows the change of ATH filler after years´ of service. It is concluded that in some dry and rainless areas, contaminants accumulated on the insulators may protect the RTV from environmental stresses such as rainfall and sunshine, which in fact plays a significant role in the hydrophobicity maintenance of RTV coated insulators. In these areas, RTV coated insulators may have longer lifespan than those used in humid areas.