Hydrophobic cycloaliphatic epoxy insulators-leakage current suppression study with a gradual contamination clean fog test

A newly developed hydrophobic cydoaliphatic epoxy resin was compared to a standard outdoor epoxy and a liquid silicone rubber regarding leakage current suppression on polluted insulators under clean fog conditions. The test insulators were artificially polluted using a special "dry-mixing" method to achieve a gradual contamination, which is similar to natural contamination processes. Leakage currents over the electrically charged insulators were monitored after exposure to clean fog. The resulting data were evaluated based on maximum and effective leakage currents, accumulated charges, pulse counts and retention times. The ability of the hydrophobic epoxy to suppress leakage currents was clearly better than that of the standard outdoor epoxy and more or less comparable to the tested silicone.