Study on Space Charge and DC Breakdown Characteristics of Polypropylene-Based Insulation Interface in Cable Factory Joints

Space charge and breakdown characteristics of polypropylene-based insulation interface in cable factory joints (FJs) are studied in this paper. In the FJ insulation manufacturing process, the locally reduced wielding temperature (WT) results in microdefects at the interface. The microdefects may be the key factor contributing to the decline of insulation performance. In the normal direction of the interface, hetero-charges primarily accumulate within the insulation, while homo-charges tend to accumulate along the tangential direction. The breakdown performance along the tangential direction of the insulation interface is inferior to that in the normal direction. In the FJ design, special attention should be given to interface microdefects and tangential insulation performance.