Propagation of Electrical Trees under the Influence of Mechanical Stresses: A Short Review

Abstract

The present paper deals with the phenomenon of electrical treeing in solid insulation, under the influence of mechanical stresses. In this short review, it is indicated that mechanical stressing can affect the propagation of electrical trees and –depending on whether it is tensile or compressive-it can facilitate (or render more difficult) the breakdown. In aged insulating materials, electrical trees can appear very quickly and can lead to breakdown. electric field direction appears causing crazing when a critical value is reached. Crazing may develop to a void crack and gas discharges will expand the tree channel even further. Earlier work has also pointed out that repeated Maxwell stresses result into the time to initiate trees decreases with increasing frequency [8]. It is in the context of applied mechanical stresses that the present paper will try to give a short review of the propagation of electrical trees. In the context of the present review no mention will be made of water trees, which are altogether another significant factor affecting the lifetime of electrical insulations.