Formal Theoretical Foundation of Electrical Aging of Dielectrics

Based on the rate theory of chemical reactions, a quantitative mathematical model of electrical aging of dielectrics is established. The empirical aging law Vn t=C and associated Weibull failure distributions for a constant voltage test are demonstrated to be approximations of the exact formulas derived. The meaning of constants n and C is explained. New parameters controlling the rate of aging are identified and shown to be the material constants, independent of the test voltage or time. Generalization of the aging law for an arbitrary test voltage profile is outlined. The life characteristics, dielectric strength degradation curves and Weibull distributions for constant and linearly rising test voltages are described in detail.