Space Charge Accumulation Model of Multi-layer Oil-Paper Insulation under DC Electrical Field

Abstract

Space charge could constrain and impact the electric strength of transformer oil-paper insulation. It is also the important factors that lead to oil paper insulation aging and insulation failure. For converter transformer oil paper insulation system, understanding the space charge accumulation behavior is particularly important for inhibit the space charge effect. In this paper, the space charge accumulation model of multi-layers oil-paper insulation was established based on the experiments. Results show that the polarity of the accumulation charge at the interface between oil gap and oil impregnated insulation pressboard is opposite with the other side of the oil immersed pressboard. Space charge accumulation behavior of the more complex insulation structure can be deduced according to the space charge accumulation model of oil impregnated insulation pressboard, two layers (oil + pressboard) and three layers (pressboard + oil + pressboard) oil-paper insulation.