Effects of Insulating Paper Thickness on Space Charge Characteristics in Oil-Impregnated Paper Insulation

Oil-paper insulation is the main form for converter transformers insulation. The space charge characteristics under the action of direct current electric field is obvious in voltage conversion. In order to reveal the physical mechanism of the effect of insulating paper thickness on the space charge characteristics, a bipolar charge transport model is introduced. Three charge transfer processes of trapping, de-trapping and recombination are fully considered in this paper. The effect of insulating paper thickness on space charge characteristics is investigated. The results show the thickness of the insulating paper has a decisive effect on the width of the low-density trap region within the dielectric. Electric field distortion within the dielectric deepens as the thickness of the insulating paper decreases.