The initiation phenomena of electrical treeing in XLPE cable insulation

Since the XLPE cables are widely used in power system and electrical treeing is one of the major breakdown mechanisms for solid dielectrics subjected to high electrical stresses, it´s of great importance to study the electrical treeing phenomena in XLPE cable insulation for the improvement of safety and reliability of power system. The process of electrical treeing includes three stages: initiation, propagation and breaking down. In this paper, the initiation phenomena of electrical treeing in XLPE cable insulation are studied. XLPE samples are obtained from a commercial XLPE power cable, in which electrical trees have been grown from pin to plane. The process of electrical treeing in XLPE samples are uninterrupted recorded by an online microphotograph system. The growing time and structure of tree initiation subjected to various voltages, frequencies and pin-plane spacings are analyzed. The results show that trees in different structures have the similar initiation structure. With the larger voltage and shorter pin-plane spacing, the time for initiation was longer and less dispersed. The influence of frequency on initiation is relatively small.