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

Summary

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 then streamer could be easy to progress, and therefore the leakage distance could not work effectively. It means that withstand voltage may be reduced when unbalance of voltage concentration is made on the polymer insulators. The reason of non-uniform contaminated conditions might be due to partially loss of surface hydrophobicity.

Additional informations

Authors

Itou, Sasaki, SHIMADA