Abstract: Overload and direct current (DC) components increase the effective value of the conductor current. When the effective current exceeds the maximum current-carrying capacity, additional losses occur, leading to temperature rise and even electrical fires. To address the insufficient research on temperature field evolution and fire risk assessment of multi-core cables under overload and DC components, this study develops an electromagnetic-thermal coupling model of the WDZ-YJY (4×50+1×25) five-core cable using COMSOL Multiphysics, to simulate the temperature field under different overload levels and DC components. The results show that under normal operation, the core temperature is 61.61 ℃. As the overload factor increases, the core temperature rises and gradually approaches a steady state. At 1.3 times overload, the maximum core temperature reaches 90.35 ℃. When the DC component increases from 1% to 10%, the core temperature shows a slight upward trend, reaching 64.56 ℃ at 10%. Overload causes a significant temperature rise, and once it exceeds the safety limit of 90 ℃, it accelerates insulation aging and triggers potential fire hazards. The thermal effect of DC components is relatively weaker than overload, but high DC levels still lead to notable temperature increases. This study provides a basis for evaluating cable operational status, supports thermal risk identification and alarm threshold setting in early fire monitoring systems, and enhances the assessment and early warning of multi-core cables under complex operating conditions.

Key words: five-core cable, overload, DC component, electromagnetic-thermal coupling, temperature field