Electrical treeing behavior in XLPE under kHz-AC voltage

Abstract

Cross-linked polyethylene (XLPE) has been widely used as insulating material in power cable. Electrical tree formed within the XLPE has been considered as an important reason for the accelerated ageing and early breakdown of the insulation. From the viewpoint of safety, it is very necessary to gain a firm understanding of the nature of electrical treeing phenomena. In this paper, XLPE has been employed as test sample to investigate the influence of kHz-AC voltage on the treeing behavior. It has been found that bush trees are formed at such a high frequency range and the density of the tree appears to increase with the frequency, whereas the time to breakdown tends to decrease. It is suggested that partial discharge within the tree channel is strengthened with the frequency and thereby the deterioration of the material is accelerated.