Effects of antioxidants on the initiation and growth of electrical trees in XLPE

Experiments were carried out using cross-linked polyethylene (XLPE) samples containing phenolic and sulfur type antioxidants to study the effects of antioxidants on initiation and growth of electrical trees. The experimental results demonstrated that the phenolic antioxidants in XLPE have the clear effect of suppressing initiation of trees generated under ac voltage stress. Moreover, the results demonstrated that the antioxidants have an effect of inhibiting tree growth. Analyzing the experimental results elucidated the mechanism of electrical tree suppression by antioxidants. It was inferred that the radical trapping effect of the phenolic antioxidant is responsible for preventing tree initiation and growth. Antioxidant effects on the electrical tree generated by grounded dc voltage are also discussed.