Effects of metal particle material on surface flashover performance of alumina-filled epoxy resin spacers in SF₆/N₂ mixtures under DC voltage

When metal particle is attached on spacer surface, it will distort surface electric field and may reduce surface insulation level. Therefore, it is important to research the relationship between metal particle attachment and surface flashover property. In this study, the effect of metal particle materials on surface flashover performance of alumina-filled epoxy resin spacers in SF₆/N₂ mixtures is investigated. Three kinds of metal particle materials including copper, iron and aluminum are considered. The results reveal that, at low gas pressure or low surface electric field, the material of metal particle has no obvious effect on flashover voltage. At high gas pressure and high surface electric field, the flashover voltage is almost the same when the iron or aluminum particle is attached, which is lower than that with copper particle attached. It is revealed that at high pressure and high electric field, metal powders and vapor of micron size can be generated from the attached metal particle surface by electric field forces and Joule Heating Effect, which may be responsible for the difference in flashover voltage for different metal particle materials.