Direct Fluorination of Epoxy Insulation: from Sheet Samples to GIS Actual Spacers

Under HVDC, insulator surface tends to accumulate charge. Excessive charge build-up on the insulator surface can distort the electric field and pose a serious challenge to the safe and reliable performance of the insulation system. Direct fluorination has become an important means of surface modification of the insulating material due to its simple process, mature technology and low cost, providing a method for surface modification of epoxy insulators. This paper reviews the research status of direct fluorination of the epoxy insulator at domestic and foreign, and summarizes the physiochemical characteristics, basic electrical properties, DC flashover and discharge resistance performance of the epoxy fluorinated layers. Under normol fluorination conditions, fluorine atom form a micron-thick the fluorinated layers on the epoxy insulator surface through substitution or addition reactions. The fluorinated layer inhibits charge build-up on the epoxy insulators surface since it has a high surface conductivity. Due to the formation of the fluorinated layers, DC flashover and discharge resistance of epoxy insulators are significantly improved. Finally, the prospects of the direct fluorination means for future industrial application of actual spacers are envisaged.