Inherent Correlation Between the Breakdown Strength and the Surface Flashover Performance of Epoxy Resin in N2 Atmosphere

Surface flashover and breakdown are two typical failures of insulations, which inhibit the stability and downsizing of electrical apparatus. The two phenomena were traditional considered be affected by different factors. However, in the present study, the inherent correlation between surface flashover and gas breakdown strength was revealed. Experimentally epoxy resin composites with a thickness of 1 mm and diameter of 50 mm were prepared. Surface flashover voltages were measured for DC voltage in different pressure and temperature. Gas breakdown voltages were tested in a same condition. With temperature decreases or pressure increases, both gas breakdown voltage and surface flashover voltage increase. However, the growth rate is different for the two voltages. Gas breakdown voltage increases faster than surface flashover voltage. The ratio of flashover voltage to gas breakdown voltage decrease with gas pressure increase. This work investigates the relationship between surface flashover and gas breakdown by considering gas adsorption. It was found that sample gas adsorption capacity can affect the surface flashover voltage, but a saturation point exists. When the adsorbed gas molecules of samples reach saturation, the effect of adsorption on surface flashover performance is less than the effect of pressure on gas breakdown voltage.