Performance of Heavy Duty UHV Disc Insulators Under Polluted Condition

This report presents results of investigation into the pollution performance of disc insulators with M& E ratings of 66,000-, 90,000- and 120,900-lbs. intended to be used for UHV systems compared with others. Fog type disc insulators have a withstand voltage 140 to 160% of the corresponding standard disc insulators. Withstand voltage is proportional to string length up to 500 kv (860 kv phase-to-phase). An insulator with larger diameter has a lower withstand voltage per leakage distance if pollutant deposit density is the same, and collects less pollutant deposit in a naturally polluted atmosphere.