Long-term tests of HVDC insulators under natural pollution conditions at the Big Eddy Test Center

In order to improve the understanding of pollution or moisture-triggered flashovers a joint four-year test was initiated to evaluate DC insulators under natural pollution and wetting conditions. The main purpose of the test is to establish correlations among flashover, equivalent salt density deposits, and weather, optimize scheduling of cleaning, study the influence of different shed forms, and demonstrate the efficiency of a water repellent coating. This report summarizes the results obtained during the first two years.>