Simulation study on the effect of interface charge between oil and paper

According to our former investigation on space charge properties of two layers of oil-impregnated-paper and oil, the interface charge between oil and paper showed different properties with Maxwell-Wagner theory in which macroscopic conductivity and permittivity were only taken into consideration. It is assumed that the charge barrier existing at interface was responsible for the interfacial charge formation. For verifying the charge barrier, in this paper, we built a numerical model to study the charge barrier effect under different voltages and oil depths. The result showed that due to the different mobilities of electrons and positive charges, the amounts of interfacial charges were different under positive and negative voltages, and the increasing of oil depth would reduce the interfacial charges. Furthermore, we used this model in multi-layer of oil-immersed-paper and oil to investigate the effect of interface charge on electrical field distortion.