Toshiyuki Kawaguchi

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.

Influence of Fog Parameters on Withstand Voltage of Contaminated Insulators

This paper describes the investigation results of fog parameters which affect the withstand voltage of contaminated insulators. As a result, the guideline is proposed on fog conditions such as density, droplet size distribution, temperature rise in the fog room, and so on, basing upon the comparison between natural and artificial fog conditions and the relation between fog condition and power-frequency withstand voltage.