Effect of altitude on the flashover voltage of contaminated insulators

Contamination flashover of insulators depends not only on the severity and type of contamination, but also on the altitude at which these insulators are situated. Reduced pressure or air density combined with light contamination at high altitudes decreases the flashover voltage. Experimental testing of a number of insulators for a wide range of outdoor conditions is time consuming as well as expensive. This paper presents the results of an investigation on the ac flashover voltages of contaminated insulators at reduced pressure using a numerical model. The model results agree well with experimental data.