Breakdown Characteristics of Solid Dielectrics Immersed in High Pressure Gaseous Media and Subjected to Direct Voltages with Ripple

The breakdown characteristics of polymethyl methacrylate (PMMA), immersed in high pressure gaseous media such as CCl2F2 and mixtures of CCl2F2 and N2, subjected to both positive and negative direct voltages with ripple contents of various percentages are reported. The peak breakdown voltage of the solid dielectric immersed in the gaseous media decreases with increasing ripple content and pressure of the media. In mixtures of CCl2F2 and N2, the peak breakdown voltage at any ripple content increases with increase of N2. The breakdown is initiated by the surface dis charges. The decrease in breakdown voltage with the increase of ripple content and pressure is attributed to the energy density of surface-discharges.