Flashover Test at Project UHV on Salt-Contaminated Insulators

The results of experimental studies on the contamination flashover strength of different shapes of transmission line insulators are presented. Insulators with mechanical strengths from 15 000 to 90 000 pounds and with disk diameters from 10 to 152/4 inches were used on these tests. New types of fog insulators with high creepage distance showed better performance than the others. Tests on long insulator strings also have been conducted for standard-type disk insulators. Nonlinearity of insulation strength with insulator length was indicated at voltage levels of 350 kV and above, i.e., 600-kV phase-to-phase voltage. These tests employed the steam- fog method used at General Electric's Project UHV since May 1968.