Influence of fluorination time on surface flashover of polymeric insulation

Charge build up under high voltage DC is a big concern in transmission system as its presence distorts the local electric field. By chemically treat polymeric insulation via fluorination process, the charge transport characteristics of the material can be modified. In doing so, excellent surface properties of fluoropolymers can be attained without compromising the bulk properties of the original polymeric insulation. The change in chemical components at the surface of polymeric insulation should lead to corresponding change in electrical properties at the surface and consequently suppress charge build up. The purpose of this paper is to review recent research into the fluorination of epoxy resins in order to suppress charge accumulation and improve surface DC flashover strength. Surface DC flashover test using a pair of finger electrodes had been conducted. Modelling and simulation of electric field and current density distribution had also been carried out for the fluorinated polymeric insulator. It has been found that the introduction of fluorinated surface layer on epoxy resins plays an important role in improving the surface dielectric properties as evident from experimental and simulation results. The influences of fluorination process on surface flashover mechanisms were thoroughly discussed.