Surface charging phenomena on HVDC spacers for compressed SF6 insulation and charge tailoring strategies

Surface flashover of spacers is a key factor limiting the application of HVDC GIS/GIL, while the charge accumulation on the surface of the spacer could have a potential adverse effect on the surface flashover voltage. This paper discusses the laws regarding distribution patterns of surface charges and the related mechanisms. The field-dependent property is discussed in detail to comprehensively illustrate the charge transport mechanism and explain the research differences regarding different surface charge patterns obtained by previous researchers. In addition, the main surface charge control methods for epoxy resin are summarized and discussed. The potential research directions of charge control methods and key points in manufacturing of spacers used in HVDC GIS/GIL are also explored.