Performance of RTV Insulator Coatings Based on Filler Type

This paper discusses the performance of RTV silicone rubber high voltage insulator coatings (HVIC) based on the type of filler used. The present-day emphasis on evaluating coating performance is based on their ability to withstand dry band arcing heat in the IEC 60587 inclined plane tracking and erosion (IPT). This has led to RTV coatings having either alumina trihydrate or quartz filler. At high filler loadings, both types of fillers show similar performance in the IPT. However, a significant difference in performance is observed in salt-fog tests which can be attributed to the type of filler in the coating formulation. This paper discusses these results to emphasize that hydrophobicity retention is the key performance indicator of RTV HVIC and that quartz is the preferred filler.