ABSTRACT Local overheating and insulation aging caused by high‐temperature environments are the primary factors reducing the electrical lifespan of transformer valve‐side bushings. Structural optimization or external shielding devices have partially improved the internal physical field distribution. However, their cooling efficiency and cost under extreme operating conditions remain questionable. This study investigates the electro‐thermal‐fluid coupling characteristics and temperature rise of transformer valve‐side bushings under extreme conditions. A novel cross‐shaped quarter pipe with micro‐oil‐cooling structure is proposed. A 3D fully coupled electro‐thermal‐fluid model with temperature‐dependent material parameters is established to validate the solution. Simulation results demonstrate that the proposed structure reduces the hot‐spot temperature at the high‐voltage end by 25.4%. The axial average temperature decreases by 23.7%, while the radial temperature gradient drops by approximately 67.9%. This effectively suppresses the “dual‐peak” temperature rise phenomenon observed in conventional designs. Multi‐condition validation under ambient temperatures of 25–45°C and oil temperatures of 30–90°C confirm the optimized design significantly enhances heat dissipation in extreme conditions. The study provides theoretical foundations and technical solutions for thermal management in high‐voltage equipment.
Lei et al. (2026) studied this question.