Dielectric Breakdown Voltage Testing - Part 2
There are three methods for dielectric breakdown voltage testing. The oldest, the flat disk method, is not very sensitive to the presence of moisture and not sensitive to changes in moisture content, unless the percent saturation of the oil is greater than 60 percent. The method is also not sensitive to the aging and oxidation of the oil. In spite of the fact that the application of this method may be limited in mineral oil filled transformers with regard to moisture increases and oil aging, D877 dielectric breakdown voltage determinations continue to yield important information for a wide variety of equipment types and insulating liquid types – including oil filled transformers. Therefore, SDMyers continues to recommend the test for purposes of providing that information.