A novel integrated low voltage apparatus with imbedded computer as core is presented in this paper. By means of power electronic technology, it integrates the total functions of contactor and circuit breaker. The three dimensional electromagnetic field and dynamic characteristics of the electromagnetic system is computed and analyzed based on the numerical computation in this paper. The influence of counterforce, coil diameter and number of windings for the breaking velocity and resetting time during switch-off is studied. Furthermore, the prototypes are tested, and the results show a good agreement with the predictions.