Arc propagation along an electrolyte surface

Flashover of wet polluted insulation is caused by the propagation of arcs along the wet surface. The paper describes experimental work which has been carried out with simple models to investigate the conditions under which arc propagation occurs. It has been found that arc propagation can be explained in terms of a new mechanism which may be called `elongation by ionisation and successive root formation¿. This mechanism depends on the discharge current being shared between the developing portion of the discharge and the electrolyte in front of the discharge tip. The experiments also show that, at all stages in the flashover process, the arc-voltage gradient is close to the value for a static arc in air at the same current.