Design of intelligent temperature control system of SF6 circuit breaker to prevent SF6 from liquefaction

SF₆ circuit breakers are widely used in power system because of its excellent arc interruption performance. But the liquefaction of SF₆ gas at extreme cold area affect the reliability of the circuit breakers. To solve the problem, an intelligent temperature control system for the SF₆ circuit breakers at cold area, the internal heating belt and their installation methods are designed in this paper. A test box to simulate the low temperature environment is built. And the cooperating performances of the temperature control system and the SF₆ circuit breaker are studied from three aspects, the working temperature of circuit breaker, the heating power and the installation position of the heating belt. In addition, the 3D models are built in workbench based on different test schemes, and the temperature rises of the models are simulated. The results prove that, the cooperation of intelligent temperature control system and the circuit breaker is stable, and the measurement error of temperature is less than 1°C. As the 500w heating belt added at the bottom of the gas chamber, the temperature of gas chamber can be maintained at more than -15°C when the external temperature is -40°C.