1998 Volume 118 Issue 4 Pages 406-412
Arresters composed of a series gap and ZnO element have been widely applied for 6kV distribution systems. The purpose of the present paper is to clarify the causes for the changes in the performance characteristics of the arresters operated by surges. The experimental arrester with no spacer is operated by a nominal discharge current under atmospheric air. Then, the impulse discharge and post-discharge phenomena are observed by means of a method connected an image-converter camera to a Schlieren technique.
In the impulse discharge process, a shock wave, the reflected shock waves and the disturbed flow of neutral gases occur in the series model gap. The shock wave can be first observed at the periphery of the luminous channel of arc after the discharge current has risen to the peak value. The disturbed flow occurs even in the weak discharge process which the discharge current was lower and the pronounced light emission from positive column disappeared, and continues for a long time until the end of the post-discharge. It is discussed that how the shock waves and neutral density change influence on the characteristics of the actual arresters for the distribution systems.