Porcelain insulator maintenance with RTV silicone rubber coatings

The selection, application and performance of RTV (room-temperature vulcanizing) coatings for the maintenance of porcelain insulators are examined. The ability of coating systems to suppress leakage current, thereby eliminating the cause of wood pole fires and flashover, is discussed. The conditions associated with the temporary loss of coating hydrophobicity and its return are also discussed. Coating life expectancy is considered in terms of the pollution conditions, the frequency of maintenance cleaning, and the formulation of the RTV coating system. It is concluded that RTV coating systems perform by virtue of the fact that they are able to suppress leakage current. This enables insulation systems to attain increased flashover performance of about 30% over uncoated insulations. Under severe conditions of pollution, the effectiveness of the coating systems is temporarily lost, showing only some improvement over uncoated insulation. However, after maintenance cleaning, the coating systems return to their initial state with only a slight loss in their ability to suppress leakage