Electrical DC breakdown characteristics of injection moulded LDPE insulation

The authors report on a study of the short-term DC electrical breakdown characteristics of injection-molded LDPE (low-density polyethylene) insulation. The short-term electric strength of the amalgamation is shown to be lower than that of other regions in the molding. However, the breakdown stress is significantly higher than the service stress of the cable system. All breakdown sites were concentrated on the boundary of the injectate and tail tube material. No structural features can be clearly associated with the amalgamation boundary. The classical flow pattern associated with injection molding and the amalgamation region is readily observed. A possible reason is because of the considerable directional variations in the orientation of PE molecules during the melt