A Study of the Performance of Contaminated Insulators Under Various Test Conditions

Two contamination test methods have been examined for the difference in assumptions used as the basis of each method. Dynamic surface impedance of insulators in a slow-wetting condition is remarkably influenced by the voltage across the insulator unit, which causes nonlinearity of insulation strength with insulator length. On the other hand, the surface condition can be represented as resistance in wet contaminant tests. This difference in surface condition naturally leads to disagreement in the results. It has been concluded to be of limited utility to discuss the order of merit for several insulators with different test methods, since any contamination method cannot simulate all aspects of this problem.