Numerical analysis of the short-time current withstand performance of the DC circuit breaker

Nowadays there is the requirement for the selective protection technology of the MCCB used in the DC power system. To achieve this goal it is necessary to improve the short-time current withstand performance of the MCCB. However, the experimental test on such a performance is quite time consuming. Therefore, it is very important to evaluate the short-time current withstand performance of the MCCB by means of simulation. In this paper a simulation model was established to describe the interaction process of the contact resistance, temperature rise, and the electro-dynamic force when the short current occurs. To be more specific, the time-varying of the nonlinear contact resistance due to the electro-dynamic force and the Joule heat are considered in the model. Based on the calculation, the temperature and the current density distribution versus time are obtained, which will be instructive and meaningful for the contact system design in the DCCB. Moreover, the simulation results have been verified by the experiment.