Leakage resistance of transmission line insulators along the coast

The leakage resistance of transmission line insulators suspended along the coast decreases with the accumulation of sea salt due to wind from the sea, particularly when the relative humidity is high. To determine the dependence of the insulation properties of a string of three standard suspension insulator units and a long rod insulator on weather conditions, a field test site was installed in Rumoi, an area on the coast of the Sea of Japan with heavy sea-salt contamination, to measure continuously the DC leakage resistance with a personal computer. It was found that the leakage resistance was affected by the wind direction, by relative humidity, and by precipitation