Influence of fluorination time on surface flashover of epoxy in insulating gas

The accumulation of charges on polymeric insulation under high voltage DC stress is a major concern in the transmission system as its formation distorts the local electric field and has an adverse impact on the electrical performance. By undergoing fluorination treatment on the insulation, improved surface properties similar to fluoropolymers can be attained without changing the bulk properties of the original material. The change in chemical components at the surface of polymeric insulation should lead to a corresponding change in electrical properties at the surface and thus can suppress charge build up. Previous research on surface flashover on fluorinated epoxy resin at atmospheric condition shows a significant improvement in flashover strength. In this paper, the authors investigated the effect of different degree of fluorination treatment on cast epoxy resin on suppressing surface charge accumulation and its contribution towards the improvement in surface breakdown strength. In comparison to previous research, it has been found that there is an optimum time duration of fluorination treatment which improves the surface breakdown strength of epoxy spacer. The mechanisms that govern the effect of fluorination treatment on surface flashover were discussed.