In-situ surface charge distribution measurement of alumina insulator surfaces after impulse voltage application in vacuum

Abstract

This paper investigates the surface charge distribution of an alumina insulator surface after flashover tests by impulse voltage applications. The measurement of surface charge distribution and the voltage testing were both done in vacuum (in situ). The vacuum chamber for the voltage flashover testing experiments was maintained at the pressure of 1.3 X 10<SUP>-8</SUP> Pa. Impulse voltage was applied with positive and negative polarity. The surface charge was measured for both positive (flashover and unflashover) and negative (flashover and unflashover) polarity. Applying the positive impulse polarity produces a positive charge on the alumina surface, when the impulse polarity is reversed both the positive and negative charges were detected in case of flashover, and only negative charge was detected in case of unflashover.