AC discharge characteristics of a needle-to-semicircular-electrode gap with solid dielectric surface under high humidity

In this study, the discharge phenomena combined with the air and the creepage discharges have been discussed experimentally with a simplified model electrode gap. A conventional frosted glass plate was used as the solid dielectric. As a result, some noticeable phenomena have been found. The flashover voltages on the solid surface depend upon the relative humidity in air and decrease with increasing humidity. Especially, when the vertical gap length (or the height) is given to the needle electrode to increase the flashover voltages, the flashover voltages in high humidity seem to be free from the vertical gap length of the needle electrode, in which the inclined angle formed with the horizontal gap length and the vertical gap length is less than 30°.