To prevent the degradation of insulation and breaking performance of sulfur hexafluoride (SF

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) circuit breakers caused by gas liquefaction under extremely low-temperature environments

this study proposes a precision thermal management strategy based on dynamic coupled simulation. Focusing on the arc-extinguishing chamber gas chamber of the LW36-126 circuit breaker

a transient model integrating solid and fluid heat transfer

natural convection

and phase change processes is developed using COMSOL Multiphysics. The complete liquefaction process of SF

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under initial conditions of 20 ℃ and 0.60 MPa is simulated

and the intervention effect of external active heating on the outer side of the arc-extinguishing chamber is systematically evaluated. The simulation reveals the non-uniform spatiotemporal evolution pattern of the liquefaction process dominated by natural convection. Through comparati

ve analysis

the effectiveness of active heating in maintaining the safe operation of the gas chamber is quantitatively verified

and its thermodynamic operational boundary is clarified. This study advances the low-temperature protection design of SF

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circuit breakers from static empirical estimation to dynamic simulation-based optimization

providing a reliable theoretical basis and decision-making support for establishing accurate and efficient anti-liquefaction design methods and intelligent control strategies.