Thermal Simulation Of Air Circuit Breaker’s Bar And Bridge Contact

Air circuit breakers are widely used in various control systems and power systems; its performance directly affects the stability of the system. Temperature rise is of great significance in the low-voltage apparatus design process. To guarantee the low-voltage apparatus can work reliably and have a certain service life. The study of heating is done in a variety of working conditions. In order to ensure the maximum temperature does not exceed the corresponding limit permitted value, the proper thermal design becomes more and more important with the increasing performance and miniaturization demand of switch gear devices. The thermal simulation can cut the costs for experimental investigations and shorten the development cycles.Based on the thermal analysis of air circuit breaker, a thermal model of bar and bridge contact is proposed in this paper, considering the conduction in the bar and the convection and radiation around the exterior surfaces. The electromagnetism method of ANSYS is adopted to calculate the loss by contact resistance; the temperature distribution of the electric connection is calculated by the thermal-electric method. The temperature field of an air circuit breaker’s bar and bridge contact with rated current of 400 A is simulated in this paper. On this basis, the temperature distribution of different forms of heat dissipation and different ambient temperatures is compared. Then the results are verified by experiments and the reasons of high temperature are analyzed. The results are useful for designing drawer.