Withstand Voltage Test Results of Polymer Insulators under Non-uniform Contaminated Conditions

Sometimes unknown flashover has been happened to even hydrophobic silicone rubber polymer insulators, which have superior contamination withstand voltage performance compared with conventional ceramic insulators. In some reports, unknown flashovers of the polymer insulators were caused by bird dropping, heavy rain or non-uniform contaminated conditions. However, the unknown flashover mechanism of polymer insulators has not been clear yet. As one reason of unknown flashover, non-uniform contaminated polymer insulators were tested by clean fog procedure. From the some test results, contamination withstand voltage of non-uniform condition reduced approx. 20% compared with those of uniform conditions. It might be because the applied voltage might concentrate the lighter contaminated areas and…