Conduction Phenomena of AC- and DC-XLPE Analyzed by Q(t) Method

Abstract

The direct current integrated charge method (Q(t) method) is a useful method to understand the dielectric properties of insulating materials in a simple manner. As total current flowing through an insulating material is integrated by a capacitor, Q(t) data includes various kinds of information about the material in it. To understand Q(t) data, in particular as it relates to electric charge behaviors, a parameter “charge ratio Q(t_m)/Q(0)” which is the ratio of the initial charge amount Q(0) (=CV) and the Q(t) after time t_m is introduced. The relation of the charge ratio, relaxation time and measured time, and analyzing method to distinguish electrode, accumulation and conductive charges are revealed in this paper. Q(t) data of AC- and DC-XLPE are evaluated according to the algorithm.