Embodiments of an automatic single- or multi-pole circuit breaker for use in low-voltage applications are disclosed. The circuit breaker includes at least a first fixed contact this is coupled/uncoupled with a first moving contact. The moving contact is operatively connected to an operating mechanism that enables its displacement. The circuit breaker includes a kinematic tripping device driven by means of a first separating movement of the moving contact away from the fixed contact. The kinematic tripping device includes an operative member capable of tripping the operating mechanism, which in turn takes effect on the moving contact, thus determining a second rapid separating movement until the circuit breaker tripped position is reached.