Interface Effects on Tree Growth of Cross-linked Polyethylene

抄録

It is well known that treeing is one of the main causes of breakdown of CV cables. It has been also considered that the interface exists between two solid insulation materials become a weak point on the electrical strength of CV cables. Therefore, it is important to reseach on the tree growing properties when there exists an interface. For evaluating the interface effect on the AC tree growth, an experimental investigation has been carried out by preparing an interface between two cross-linked polyethylene(XLPE) blocks. This paper describes the experimental results under various interface conditions. It was found that the interface had a great influence on the tree growth. The time to breakdown was reduced by the interface in the present test conditions. Painting the silicone oil on the interface, not only reduced the time to breakdown but also prevented the breakdown through the surface of spec imen(B). And the pressure applied on the interface had a slight effect on the time to breakdown but on the tree growth pattern. With the increasing of applied voltage, phenomena above mentioned were more significant It is proposed that the discharge column activities and the gas pressure reduction in the tree channels play important roles in the present situation.