Wet Surface Tracking of Insulation: A Differential Test with Controlled Short Discharges to a Water Electrode

A basic study of wet tracking failure of insulation has shown that conducting track growth on moist surfaces usually results from a succession of short tracks caused by short discharges. An in vestigation of such short discharges, at controlled power levels, between a metal and a water solution electrode has led to a rapid procedure for evaluating the relative track resistance of materials. The results correlate well with some service experience and dust and fog and inclined-plane tests. Surface and internal tracking can be distinguished.