Effect of Structural Morphology on Space Charge Characteristics of Epoxy/paper Composites

Epoxy/paper composites are the main insulating materials for high voltage dry bushings. During the long-term operation under the combined action of high voltage and high temperature, the accumulation of space charge inside the material will distort the local electric field, aggravate the aging process, and even cause partial discharge or insulation failure in severe cases. In this paper, the space charge characteristics of epoxy/paper composites at different temperatures and electric fields were studied. The influence mechanism of structural morphology on space charge dynamics was explored by comparing three different structures: pure epoxy (EP), epoxy resin impregnated paper (RIP) and sandwich-structured EP/RIP/EP composites. Experimental results show that homocharge accumulation occurs in the adjacent areas of electrodes for all samples. Under the conditions of high temperatures and high fields, charge accumulation becomes severer due to an increase in charge injection and charge migration rate. The higher the temperature, the more severe the electric field distortion inside the sample. Under the experimental condition of 60°C and 16kV/mm, the space charge suppression ability of EP is better than that of RIP. This research aids an understanding of space charge characteristics of epoxy/paper composites and provide guidance for material design in engineering practice.