SURFACE DISCHARGES ON POLYMERIC INSULATOR SHED SURFACES

This paper describes results of an experimental investigation into sur face discharges occurring on the surface of polymeric insulators. Disc harges on partially hydrophobic surfaces were found to occur across we ll defined dry bands, while discharges on hydrophobic surfaces appeare d as small points of light occurring between discrete water drops. The se discharges were observed to produce a localized loss of hydrophobic ity. It is shown that these discharges are stable atmospheric-pressure glow discharges. The discharges are characterized by a high cathode v oltage fall, dependent on the electrical conductivity of the water dro p, and a voltage gradient in the positive column, dependent on the dis charge current. A technique is presented for measuring the rate at whi ch surface hydrophobicity of polymeric materials is lost due to the ac tion of this type of discharge. It was found that the loss of hydropho bicity occurred predominantly in the region near the cathode.