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Abstract
Coating of room-temperature vulcanized RTV) silicone rubber is increasingly being used by power transmission utilities. This is to overcome the contamination problems encountered in porcelain and glass insulators particularly under wet conditions. An important property of the RTV silicone rubber coating is its ability to restore the hyDROPhobicity of the surface after a layer of contamination builds up on it. This layer continues to suppress the development of leakage current, dry band arcing and flashover. The porcelain and glass insulators have high surface energy. They are wet readily when exposed to fog, dew, or rain. When these traditional insulators operate under moisture and contamination conditions, there is a high possibility of suffering from leakage current, leading to flashover which is followed by an outage of the power system. A clean fog chamber has been fabricated and a data acquisition system (DAS) was prepared to conduct tests on insulator samples. The hyDROPhobicity is determined by measuring the static contact angle between the tangent to a DROPlet of distilled water and the horizontal insulator surface. The electrical performance of the RTV silicone rubber insulator coatings in the clean fog chamber has been experimentally investigated. The influences of coating thickness and pollution level on the leakage current were investigated Mechanisms by which these two parameters affect the performance of coated insulators are suggested, investigated and discussed.