Surface flashover of the ATH/epoxy under the nanosecond voltage pulse

The epoxy insulators are widely used in the vacuum equipments. Some investigators suggest that the surface flashover voltage of epoxy resin is improved by inorganic fillers. The fillers maybe restrain the accumulation of the surface charge. This paper use the Al₂O₃·3H₂O powder(particle size of 1um)to improve the voltage holdoff capability of the epoxy insulator under nanosecond voltage pulse. The waveform 30ns/500ns and the vacuum level of 5×10^-3 Pa are chosen in the serial experiments. Where different mass fraction of the Al₂O₃·3H₂O powder are added into the epoxy resin,the results of surface flashover voltages are considered. Comparing these results,we can conclude that all samples have a similar tendency with a systematic decrease in pulse durations with increasing peak values. When we wish the surface flashover occur at the pulse duration time of 100ns or 80ns, relationship between the surface flashover voltage and the different weight percent ATH powders of epoxy has a similar tendency. The surface flashover voltage is decreased at 20 wt%, then increased at 40 wt%, and then become stable from 60 wt%. Then if the duration time 60ns is set, the surface flashover voltage of epoxy composite with fillers (80 wt% and 100 wt%) is equal to or even higher than that of pure epoxy resin.