Expansion characteristics of a discharge column in an electrode–ice gap

Abstract

When modeling the propagation of an electric discharge on an ice-covered insulator, the diameter and temperature of the discharge column are vitally important. This paper studies the thermal expansion characteristics of a discharge column occurring after electrode–ice gap breakdown both experimentally and theoretically. It is found that the air part of the discharge channel expands faster and has a higher temperature and larger diameter than the surface part. To provide a quantitative explanation of this phenomenon, a physical model is established based on the gap breakdown process, discharge channel heat conduction, and molecular thermal relaxation theory. The results of theoretical calculations show that the experimentally observed differences in discharge column thermal expansion characteristics result from the heating effect of brush discharge and from differences in heat conduction around the column.