RTV Insulator Coating: State of the Art and Research Needs

Abstract

Initially applications of RTV silicone material have been conceived as a remedial measure to mitigate pollution-related flashovers of insulators suffering poor service performance. Nowadays the pre-coating solution, coating process carried out in factory on new insulators, is prevailing and is one of the possibilities to be considered for insulation solution in harsh environment, either for new installation or for substitution of insulators with poor performance. Their use is increasing exponentially and nowadays more than 7 million pre-coated cap and pin insulator units are installed on overhead lines around the world. The solution is also extensively used for power-station insulators.

The paper describes the pre-coating evolution, from manual process to a fully automatic solution. The fully automatic pre-coating system leads to increase in quality and productivity, guaranteeing uniformity of the coating thickness. Furthermore, automatic system works in controlled environment, reducing silicone waste and contact of operators with chemical products, drastically decreasing environmental pollution, production costs and risks for workers.

Despite the evident market evolution, no international agreed Standard on high voltage insulators coating is yet available. The new CIGRE WG B2.69 aims to give a valuable contribution toward Standardization, summarizing the knowledge available on the matter and the state of the art. A voluntary international R&D program has been also established to investigate the performance of different coating solutions in various harsh environment conditions. The R&D program foresees realization of experimental campaign aiming at increasing the confidence on the RTV silicone coating solution, as a contribution to the Standardization development. The R&D program and experimental tests are presented and discussed in the paper.