Study on Thermoelastic Deformation of Bimetal Sheets in Miniature Circuit Breakers

The overload protection of a miniature circuit breaker is mainly accomplished by the deformation caused by the heating of the bimetal sheet, which affects the performance of the miniature circuit breaker directly. Accurate calculations of thermal distribution and deformation degree of the bimetal sheet are significant to the design of miniature circuit breakers. In this paper, the temperature change and deformation process of the bimetal sheet at various instants are studied. Firstly, a finite element model of the bimetal sheet is built. Then the heating process of the bimetal sheet under different current values is simulated. The transient temperature distribution and the real-time displacement curve of the bimetal sheet are obtained. Meanwhile, the corresponding experimental research is completed. The maximum errors of temperature and deformation are 2.8 K and 0.026 mm respectively and the relative errors are 6.4% and 2.8% respectively. The correctness of the simulation method is verified. The simulation model can provide a empirical basis for the optimal design of a circuit breaker.