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

The properties of space charge and breakdown in epoxy/paper composite were studied. The results show that the breakdown voltage of epoxy/paper composite is lower than epoxy under AC voltage, but is higher under DC voltage. In order to explain this phenomenon, space charge behaviors were investigated. In the epoxy/paper composites, space charges were easily gathered at the interface of epoxy and paper at low field and the electric field distribution was intensely deformed. However, the amount of interface charges decreased with the voltage increase, leading to a more uniform field distribution in the composites. This behavior was different from that in pure epoxy, resulting in the different breakdown properties in pure epoxy and in epoxy/paper composites.