Research of the Inverse Relationship Between Internal and External Temperatures of 10 kV Three-Core Cable Joints

Cable joint temperature monitoring can effectively warn of overloading problems, but the existing sensors are often attached to the surface of the cable joints, which can detect only the external temperature of the joints. To realize the early warning of cable overloading, it is also necessary to understand the inverse relationship between the internal and external temperatures of the joints. To this end, this study uses 10 kV three-core cable joints as an example, establishes a three-dimensional structural model of cable joints, and analyzes the temperature rise characteristics of the joints through the multi-physical field coupling simulation of the current-magnetic field-thermal field. On this basis, the simulation model is used to analyze the influence of ambient temperature and load current on the temperature inside and outside the joints, and to construct the inverse relationship of the temperature field of 10 kV three-core cable joints. In addition, an experimental platform for the temperature rise of cable joints is constructed, and experiments are conducted to verify the accuracy of the inversion relationship. The results show that there is a quadratic function relationship between the inner conductor temperature of the joint and the ambient temperature, load current, and outer layer temperature. The differences between the experimental results and the theoretical calculations are all less than 1°C, and the relative errors are all less than 2.5%. Through the research presented in this paper, a theoretical basis for power cable overload warning and cable dynamic capacity increase is expected to be provided.