Material Properties and Electric–Thermal–Stress Multiple Fields Coupling Simulation of Power Distribution Cable Accessories

In engineering applications, the material properties of the cable accessories are affected by electrical, thermal, and mechanical stress. In this work, the comprehensive properties of the insulation material and the semi-conductive material for the cable accessory are studied. Furthermore, the multiphysics field coupling simulation model is established to study the distribution and variation in electric, thermal, and stress fields. The experimental results show that the relative permittivity of silicone rubber (SiR) and cross-linked polyethylene (XLPE) gradually decreases with the increasing temperature, with values of 2.29 and 3.39 at room temperature, respectively. The thermal conductivity of the semi-conductive material is higher than that of SiR and XLPE, with values of 0.39, 0.21, and 0.30 W/( $\text{m}\cdot \text{K}$ ) at room temperature. In contrast, the semi-conductive material has a relatively low thermal expansion coefficient. The elasticity modulus of XLPE at room temperature is approximately 97.62 MPa. Moreover, the mechanical properties of the three materials are relatively good. The simulation results show that the electric field distortion caused by the temperature change is slight. The maximum electric field distortion point locates at the stress cone root, with a value of 2.22 kV/mm. The highest temperature of the cable accessory is approximately 50.31 °C, and the temperature difference between the inside and outside reaches 5.84 °C, which will cause a significant interface stress change. Besides, the internal temperature and temperature difference in the cable accessory vary widely with ambient temperatures and current loadings. The research will be guiding significance for material selection, structural design, and interfacial stress parameter selection of the cable accessories.