Inverse calculation and acquisition of cable joint and core temperature based on surface temperature

As a critical component of power cable systems, the tempera ture status of cable intermediate joints directly affects the safe ty and reliability of power grid operation. This paper proposes a collaborative temperature solution of "finite element modeling inversion + embedded sensing monitoring" for 10kV three-core cable cold-shrink intermediate joints. An electromagnetic-thermal coupled finite element model was established in COMSOL to analyze the influence law of a mbient temperature (-5℃~35℃) and load current (200A~600A) on the cable core temperature, and a calculation expression for cable core temperature was obtained by fitting 25 sets of simulation data. Meanwhile, a low-power temperature measurement system with STM32 as the core and LoRa as the wireless transmission medium was designed to achieve high-precision collection of surface temperature and ambient temperature (temperature measurement accuracy of ±0.8℃). By combining theoretical modeling with engineering application, this solution provides a complete technical path for the condition assessment of intermediate joints.