Study on the properties of space charge and breakdown for epoxy-paper composites

The properties of space charge and breakdown in epoxy/paper composites are studied in this paper. The results show that the breakdown voltage of the epoxy/paper composite is lower than that of the epoxy under AC voltage but is higher under DC voltage. In order to explain this phenomenon, the space charge behavior is investigated. In epoxy/paper composites, the space charges easily accumulate at the epoxy/paper interface at low fields, and the electric field distribution is highly deformed. However, the amount of interface charges decreases with increasing voltage, leading to a more uniform field distribution in the composites. This behavior is different from that of the pure epoxy, resulting in the different breakdown properties of pure epoxy and epoxy/paper composites. (c) 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.