A Modified Simulation Model Using FEM for Monitoring Transformer Insulation Health Under Non Uniform Aging

The effect of non uniform aging on the insulation performance of transformer oil-paper insulation has not been investigated much. In this paper, a modified simulation model is developed using COMSOL Multiphysics software, and the impact of non uniform aging on the electrical properties of insulation such as electric field, current density, and space charge density is investigated by comparing the distribution of these parameters under both uniform and non uniform aging. In comparison to uniform aging, the distribution of electric field at low frequencies under non uniform aging is mainly concentrated at the outermost solid insulation with its value decreasing from the outermost to innermost insulating paper region. Also, the flow of charge carriers and their accumulation takes place at the oil-barrier gap with severe aging. Total losses with uniform and non uniform aging are also compared indicating slightly higher losses with non uniform aging.