Electrical characterization of epoxy insulators by the study of the surface potential decay and return: a new interpretation by polarization processes

The authors investigate the surface potential decay after charge is deposited, and its return after surface neutralization, via polarization measurements on thick epoxy samples showing no surface conductivity. They find that the classical representation of charge injection into the volume does not fit the experiments; the main factor responsible for the decay is the presence of slow polarization phenomena. Slow polarization processes occurred in the volume under the influence of the deposited charge, which remained trapped on the surface. These polarization processes account well for the potential decay and return measurements on nonaged samples, and they can be interpreted as an absorption current which follows the classical power law