Influence of High Altitude Environment on Thermal Performance of Miniature Circuit Breaker

In a high altitude environment, the temperature rise of miniature circuit breaker increases significantly due to slow heat dissipation. Based on the principle of heat transfer, this paper discussed the influence of the difference in pressure, relative humidity and temperature in different altitudes on the heat loss of miniature circuit breaker, a three-phase intelligent miniature circuit breaker thermoelectric coupling model was established, and the thermal convection coefficient of each cooling surface under different environmental parameters was calculated, the thermal convection and thermal radiation boundary conditions was applied, it was obtained that what the difference between the internal and external temperature rise of the circuit breaker at an altitude of 4300m and that at an altitude of 0m was by simulating. The temperature rise test and the trip test were carried out under different environmental parameters, and it was obtained that how temperature rise, thermal convection power and thermal radiation thermal power change with environmental parameters changing. That the difference between the stable temperature rise and time constant of the bimetal when 1.13 times rated current was applied, the trip temperature rise and the trip time when 1.45 times rated current is applied were also obtained.