Flashover mechanism of RTV coated insulators

The use of room temperature vulcanized (RTV) silicone rubber (SIR) coatings for improving the contamination performance of existing ceramic insulation has become popular. RTV SIR coatings work on the principle of providing a high surface resistance even in the presence of moisture and contamination, hence, limiting the leakage current to harmless levels. This paper deals with the flashover mechanism and performance of contaminated RTV SIR coated insulators under wet conditions. Four types of profiles of insulators with RTV SIR coating were evaluated. The withstanding voltage and flashover tests were performed on these insulators. The equivalent salt deposit density and the non-soluble deposit density were measured. Based on the analysis of leakage current monitored, the flashover mechanism of RTV SIR coated insulators was proposed in this paper.