A novel nonlinear conductive ZnO micro-varistor/epoxy resin composite film for metallic particle deactivation in DC GIL

Enclosure coating is a promising technique of metallic particle contamination deactivation in DC gas-insulated transmission lines (DC GIL). However, the conventional insulation film cannot inhibit partial discharge (PD) at triple junction around the contact between the particle and the film, which has adverse effects on metallic particle deactivation. In the present work, we therefore fabricated electrically nonlinear conductive film by doping ZnO micro-varistors in epoxy resin matrix. And we measured the conductivity and dielectric characteristics of film with various doping concentrations. We experimentally and theoretically investigated the effects of film properties and particle radius on suppression of PD and particle lift-off statistics. The developed nonlinear conductive film was proved to effectively suppress PD and better increase the particle lifting voltage than conventional insulation film, which is of significance in the long-term reliable operation of DC GIL.