The self-healing phenomenon of non-conducting electrical trees in XLPE cables

To understand the self-healing mechanism of non-conducting electrical tree in cross-linked polyethylene (XLPE) cables, the experiments of non-conducting electrical tree aging and self-healing were down using XLPE slice samples. The experiments show, when the power disconnected in the early stage of electrical tree initiation, the light colored non-conducting electrical tree disappeared and a self-healing phenomenon was resulted in. By building growing and self-healing models, the mechanism of the non-conducting electrical tree growing and self-healing was analyzed. The study shows that, in the early stage of electrical tree initiating, because of Maxwell stress, partial discharge, charge injection and extraction, electroluminescent and other effects, the XLPE molecular chains are broken and gasified and the electrical trees grow rapidly. When the applied voltage is removed, the elastic energy stored in the XLPE material around electrical trees is released and the electrical tree diameter decreases. The XLPE molecular chains on the inner wall of the channel are overlapping staggered, so that the electrical tree channels disappear and the self-healing phenomenon occurs.