Basic leak currents of generic silicone and EPDM transmission line polymeric insulators

The differences of the surface resistance of wet and polluted realistic silicone rubber and EPDM insulator families exposed to AC and DC voltages were studied in the field station of Anneberg during two storms by recording their basic leakage currents. The insulators were mounted on the experimental line two years earlier and were already exposed to the storms of the previous year. The DC insulators were energized with +300 kV and the AC insulators with 130 kV RMS phase to ground voltage, and their dimensions were, for the DC insulators, 2700 mm±10% long (creepage distance 7000 mm±10%) and, for the AC insulators, 1300 mm±5% (creepage distance 3800 mm±10%)