The purpose of this work is devoted to know the behavior and the degradation that non-ceramic insulator samples present when they are naturally and artificially polluted with hygroscopic material. These samples were exposed to salt fog with low salinity, in order to simulate the ageing of non-ceramic insulators installed at 230 kV line located in Michoacan, Mexico. These samples were also artificially polluted when different types of pollutant were deposited over their surface by the solid layer method. These pollutants were bentonite, kaolin, slaked lime, caustic lime, cement and fertilizer. An on-line leakage current monitor was used to measure the leakage current flowing through each insulator sample. It was expected that the discharges provoked by the biggest humidity absorption in this material are degrading faster the insulator polymeric surface. The results indicate that the damage on the insulator surface depends on the type of pollutant deposited on the insulator.
