Durability of RTV-coated insulators used in subtropical areas

In recent years RTV (Room Temperature Vulcanizing) coated insulators have been increasingly applied in South China where the climate is subtropical. In order to investigate the durability of RTV coated insulators for transmission lines a comprehensive series of tests with regard to the characteristics of a subtropical climate were carried out on transmission line insulators which had been in use on 500 kV, 220 kV and 110 kV lines for operation periods of 1 to 6 years. An evaluation of the condition of these field-aged RTV coated insulators on the basis of these tests is given. It indicates that such transmission line coated insulators can operate for a long time and at least for six years.