Pollution severity performance chart; key to just-in-time insulator maintenance

Determining when to take corrective action on contaminated high voltage insulators has been a problem for electric utilities for many years. In particular, the setting of realistic threshold levels to trigger corrective action has been very difficult. This problem has become even more important because of the need for better utilization of field personnel as a result of the continuing downsizing and re-engineering of electric operating companies. There has been a renewed interest in predictive monitoring devices that can initiate just in time maintenance. This interest includes pollution monitoring devices. This paper is based on a study of both the evaluation of pollution monitors as well as actual flashover tests. Because of the statistical nature of insulator flashovers and the relative few that occur in operating companies it is necessary to conduct laboratory flashover tests to determine threshold levels. This study was done for a specific electric utility but does indicate a process for establishing procedures for other utilities to develop programs for determining when they should take corrective action on contaminated insulators.