Calculation of Pressure Distribution at the Interface of Polypropylene Insulated Cables and Joints

Thermoplastic polypropylene insulation material has excellent performance, high temperature resistance grade, recyclability, and significant economic and environmental advantages. Therefore, it has broad prospects in replacing traditional cross-linked polyethylene (XLPE) insulated cables. However, the long-term operational reliability of polypropylene insulated power cables is still being evaluated, especially the matching performance with traditional cold shrink joints needs to be effectively verified. By establishing a theoretical calculation model for the cold shrink intermediate joint structure of distribution network cables, this paper combines mechanical properties testing of silicone rubber material and Yeoh parameter model fitting to analyze the pressure distribution at the interface of polypropylene insulated cables. The study suggests that the pressure at the interface of cable joints gradually decreases radially from the inner layer to the outer layer, and the interface pressure is relatively high at the root of the stress cone and the high-voltage shielding pipe. The interference amount and conductor temperature will have an impact on the interface pressure, and a threshold analysis method for the failure of the interface pressure of the joint has been proposed, which can provide technical guidance for the matching of polypropylene insulated cable systems.