Suppression of leakage current and improving insulator voltage withstand using silicone compound coating

This paper describes the results investigation on application of silicone compound coating of ceramic high voltage insulator. Pin ceramic insulators with operating voltage of 20 kV were used as samples. Novagard silicone grease was used as the coating compound. The effects of temperature, humidity and various artificial pollutants were investigated. The experimental results show that application of silicone compound coatings suppressed leakage currents significantly under contaminated environment. Under high humidity of more than 90 % higher leakage current and lower flash over voltage were observed. The coating on the wet-polluted insulators results in a very poor improvement of the insulator properties. This showed coating method affected the performance of the coating. Coating of ceramic insulator surface suppressed the magnitude as well as the harmonic content of the leakage current. At the same time it also increased the flash over voltage