Investigation on Leakage Current of Silicone Rubber Insulator in Salt-fog Chamber

An artificial salt-fog chamber was employed to investigate leakage current of silicone rubber (SIR) insulator under the severe contamination in coastal areas. The high-frequency components of leakage current were extracted to obtain the corresponding high- frequency cumulative charge for studying multi-effects of salt-fog conductance, relative humidity and ambient temperature. The high-frequency cumulative charge, in agreement with the dry-band discharge, is associated with the magnitude and distortion of leakage current. It is found that the cumulative charge at 550 Hz shows the biggest value in the high-frequency components. With increasing the conductance from 1.0 to 3.0 mS/cm, the cumulative charge increases, but decreases from 3.0 to 5.0 mS/cm. With the increase of relative humidity and ambient temperature, the cumulative charge increases. It is suggested that the high-frequency components of leakage current have the strongest influence on the surface deterioration of SIR insulators.