Performance of Insulators Covered With Snow or Ice

This paper describes the results of investigation made into the performance of insulators covered with snow or ice. The AC and DC withstand voltages of snow-covered insulators were characterized by the conductivity of water melted from the snow. The AC withstand voltage of ice-coated insulators was characterized by the length of icicles and conductivity of the water melted from the ice. And the switching impulse flashover voltage of snow-covered insulator strings was almost proportional to gap length between the arcing horns or the insulator strings. Flashover voltage of a 75% snow-covered insulator string, which means the worst case, was 40 - 65% of the positive wet flashover voltage of the clean insulator string.