Measurement of the effects of surface roughness on flashover

Insulators in various environments are susceptible to surface degradation due to environmental factors. For example, in space, insulators are subject to constant bombardment by particles such as debris and micrometeoroids. Experiments were conducted to determine how the surface flashover voltage of the insulator is affected by such surface degradation. Ten roughness groups were tested. The various roughness groups were obtained by preparing the sample surfaces with sandpaper and polishing compounds of varying degrees of coarseness, ranging from Hash 80 grit sandpaper to .05 micron polishing powder. Results are presented on Lucite and Celcon samples. A definite correlation between flashover voltage and roughness is shown. In the case of Lucite, roughness seems to increase the flashover voltage, although the unusual characteristics of the flashover voltage vs. roughness curve hint at the influence of unknown factors.<>