Increasing the performances of various Types Outdoor Insulators by using RTV Silicone Rubber Coating

Abstract

Insulator is one of the most important equipments in an electric power system. Since long time ago ceramic insulators are widely used in transmission as well as in distribution lines. As outdoor insulators, the insulators are subjected to outdoor environmental stresses such as humidity, temperature and pollution. Under polluted and wet condition, high leakage current may flow on the insulator surface. As the result a dry band arching may take place and in the long time it may degrade the insulator and initiate the insulator flash over leading to the failure of the lines. Several efforts may be taken to improve the insulator performance under polluted condition. They are increasing the number of insulator strings, modification of insulator design to increase the creep age distance and regular washing. This paper presents the investigation results on the silicone coating on ceramic insulators under laboratory and real environmental conditions. It was found that the coating was significantly suppressed the magnitude of leakage current and drastically eliminated the harmonic content. The coating also drastically suppressed the corona on the insulator and reduced the surface temperature. The coating also significantly increased the flash over voltage of the insulator. Leakage current analysis and simulation showed significant improvement of surface resistance of insulator after application of RTV coating under most environmental conditions compared to those of uncoated insulators. Overall investigation results indicated significant improvement of insulator performances by applying RTV silicone rubber coating.