Abstract: The temperature rise formula of miniature circuit breaker terminal was derived from the thermal balance equation.The stable temperature rise coefficient and temperature rise time constant coefficient of the formula were calculated by the least-square method.An algorithm for predicting stable temperature rise from sampling temperature of the first 40 minutes was compiled,the temperature and time data of many samples at 150%T_N,120%T_N,100%T_N,and 70%T_N were taken to calculate the predicted temperature rise and the temperature rise time constant.Next,the temperature rise and time fitting curve was drawn,which fits well with the actual temperature rise and time curve.It verifies the feasibility of the temperature rise prediction algorithm.In view of the circuit breaker thermal test,only the temperature rise of the terminal and the shell can be obtained,and the temperature rise of the contacts inside the breaker,cannot be measured directly.This paper also uses finite element simulation to explore the temperature distribution near the contacts,supplementing the temperature rise measurement of the circuit breaker.

Key words: miniature circuit breaker, temperature rise prediction, least-squares method, finite element simulation