Abstract: For the prediction of overload temperatures in low-voltage five-core cables, traditional thermal-network models suffer from accuracy degradation due to multiphase heat‐source coupling, geometric nonuniformity, and the temperature dependence of resistance. To address these shortcomings, this paper develops a two-dimensional, transient temperature-field finite‐element model based on electromagnetic-thermal coupling. Taking YJV 5.0×2.5 mm² low-voltage cable as the study object, the coupled Maxwell and transient heat‐conduction equations are solved via a Galerkin weak‐form discretization and an implicit Euler time‐integration scheme to obtain cable‐temperature evolution under various operating conditions. The results indicate that under balanced three-phase loading, the B-phase core constitutes the highest‐risk zone for insulation failure; when ambient temperature rises from 15 °C to 40 °C, the steady-state core temperature increases by 27.53 °C, corresponding to an 18.68% loss increment. With load current elevated from 15 A to 35 A, steady-state core temperature rises by 81.1 °C, with losses increasing by 37.18%. Experimental validation shows that the model predicts outer-sheath temperature with a mean absolute error below 3%, and that a 3 600 s transient simulation completes within 5 min. The proposed model overcomes the simplifications inherent in traditional methods for multiphysics coupling and can be applied to electrical‐fire hazard assessment and overheat warnings, providing theoretical support for dynamic current‐carrying capacity evaluation, overtemperature alerting, and overheating protection.

Key words: five-core cable, electromagnetic-thermal coupling, finite element method, temperature field