AC Reignition Voltage on Partially Contaminated Insulator Surfaces

Abstract

In an attempt to clarify flashover phenomena on contaminated insulator surfaces, the authors have investigated the relations between the ac reignition voltage and the arc voltage characteristics at 50 Hz power frequency. The present paper discusses some of the characteristics of partially contaminated surfaces. As reported before for contaminated surfaces, the reignition voltage in each half cycle decreases with the number of reignitions, reaches a minimum, and then increases again. This characteristic is due to the thermal ionization of Na atoms diffused and accumulated in the discharge space by alternate reignitions. A similar tendency has been observed on partially contaminated surfaces. On the partially contaminated surface, however, the value of the reignition voltage depends upon whether the gap ends are contaminated or not. As a result, the critical flashover current on a contaminated insulator surface could be estimated.