Analysis of electrical tree inhibitory effect by antioxidants using quantum chemical calculation

This paper describes the effect of electrical tree inception voltage on antioxidants mixed in XLPE by using the density functional theory (DFT) approach. It already has been demonstrated experimentally that among the four phenolic antioxidants, 3-methyl-6-tert-butylphenol has the highest tree inception voltage. First, it is shown DFT calculation results which are the energy levels, electric dipole moment and 3D electrostatic potential distributions of antioxidants. We could be confirmed that the electrical tree inception voltage increases with increasing the electric dipole moment of antioxidants, and the inhibitory effect becomes larger when the phenolic antioxidant contains sulfur. The DFT approach is very useful to consider the mechanism of the relationship between tree inception voltage and antioxidants mixed in XLPE.