Influence of Screening Electrode on Surface Flashover in Atmospheric Environment

The surface flashover at atmospheric pressure is the main factor that limits the insulation performance of high-voltage devices. In order to rise the dielectric strength of the surface, the screening electrode is frequently used. In this article, the characteristics of the flashover on the ceramic surface are studied by experiments in air with different structures of the screening electrode. The effect of the screening electrode on dielectric strength is obtained by comparing the breakdown voltage of the ceramic surface with screening electrode with that of the pure air gap and ceramic surface. Besides, the evolution of the plasma under different lengths of the screening electrode is captured by a high-speed camera, and the transformation of the gas discharge to surface flashover with the decreasing shield length is observed. The competition between the two processes is discussed. The result provided a straight view and deeper understanding of the effect of the screening electrode.