Investigation on Field-Aged RTV-Coated Insulators Used in Heavily Contaminated Areas

The characteristics of field-aged room temperature vulcanized (RTV) silicone rubber coatings were investigated for use in heavily contaminated areas with emphases on the antipollution flashover performance of aged RTV-coated insulators. An atomic absorption spectrophotometer and ion chromatography (IC) were employed to study the composition of contamination deposited on the insulators, with scanning electron microscopy used to analyze the configuration of the contamination and the aged coatings. The results showed that the sample insulators were heavily polluted with significant changes of the coatings due to field aging compared to new RTV coatings. Flashover did not occur in voltage withstand tests even with high voltage. In addition, the wetting process of the lower surface was not in phase with that of the upper surface during the pollution tests, which increased the pollution flashover voltage on the sample insulators more than the reduced influence on flashover voltage caused by highly soluble salts deposited on the surfaces of the samples. All of the results showed that RTV coatings provided long available term of protection against the pollution flashover, even in heavily contaminated areas