Abstract-Polypropylene has a great electrical property and may be used as primary insulating material in electrical power cable. In cable accessory, the field distribution is often distorted since the very complicated physical structure, which makes interface discharge between PP and cable joint insulation easy to happen. Polymer based nanocomposites has recently received a lot of attentions, which can offer a better insulation property than the neat polymer. In order to improve the electrical property of the PP/SiR interface, nano-sized MgO filler has been adding into PP matrix to form the socalled PP/MgO nanocomposites. The interface discharge behavior between the nanocomposites and the SiR have been studied. Obtained results showed that with the increase in the nano-particle content from 0 wt% to 5 wt%, the interface breakdown strength firstly increases but then decreases. A proper content of 3 wt% nano-sized MgO adding can improve the interface breakdown strength by a fact of 3.5. It is suggested that the interface breakdown strength can be enhanced through the adding of nano-sized MgO.

Abstract-Electric field distribution in cable joint can be enhanced because its structural complexity, this forms interface discharge between the main insulation of cable and the insulation of cable joint. Polypropylene (PP) has good electrical property and is suitable for being used as insulation material of power cable. On the other hand, silicone rubber (SiR) has been widely used as the insulation of cable joint. The interface between the PP and SiR becomes a weak point where an discharge phenomena may be introduced. In order to improve the electrical property of the interface, a corona discharge treatment has been employed in this research, by which the surface chemical and physical structures of PP can be modified. Obtained results showed that with the treatment of AC corona, the interface breakdown time was obviously extended. It is suggested that the interface breakdown strength can be enhanced through the corona discharge treatment method.