Surface flashover characteristics of nano-composite dielectric materials under DC and pulsed signals in partial vacuum

Surface flashover is a major issue in electrical insulation in power systems, both in space or atmospheric environments. In general, random emission of a small number of electrons at the cathode results in positive charging of the dielectric surface at the triple junction, thus initiating surface flashover across the dielectric. Developments in nano-particulate and nano-dielectric materials and effects of nano-scale fillers on electrical, thermal and mechanical properties of polymeric materials have been observed. In this paper, we present experimental results of surface flashover characteristics of epoxy resin and epoxy resin cast with powdered Al2O3 in partial vacuum. The flashover experiments are conducted with DC, AC and repetitive pulsed signals separately. Surface flashover voltage and current waveforms and light emission data with PMT were recorded. The samples used in the experiments were produced by using either epoxy resin of known properties, or by mixing known quantities of Al2O3 with epoxy. The electrode material placed over the dielectric samples was copper.