Study of the Interruption Process of the Selective Miniature Circuit Breaker

摘要

The interruption process of the new type selective miniature circuit breaker (SMCB) is different from the traditional low voltage circuit breaker (LVCB). According to the operating principle of the SMCB, its interruption process can be divided into three stages; the corresponding mathematical model and calculation method are proposed as well. The calculation of the static characteristic of the magnetic release equipped with the permanent magnet shows that the influence of the current direction on the electro-magnetic force can't be ignored, which lead to the minimum tripping current of the release is equal to -315A and 490A respectively, when the armature is close to the permanent magnet. Based on the simulation and experimental results when the effective value of the prospective short circuit current is 644A and 1.5 kA, it indicates that the bigger the closing phase angle is, the quicker the arc ignition between the main contacts and the less arcing time will be. Moreover, the typical interruption parameters of the simulation and experimental results are comparable, it demonstrates that the proposed method can be used for the optimization design of the SMCB.