Low-voltage circuit breaker

A low-voltage circuit breaker includes at least one current sensor for determining the magnitude of the electric current of a conductor of the low-voltage circuit breaker; and at least one electromechanical switching unit for connecting and disconnecting at least two electrical contact points. In a first switching position of the movable contact point, two contact points are connected and in a second switching position the contact points are not connected to one another. The circuit breaker further includes at least one electronic switching unit having a semiconductor switching element, electrically conductive in a first switching state and electrically blocking in a second switching state; an electronic tripping unit, connected to the current sensor, the electronic switching unit and the electromechanical switching unit. Further, when current and/or current/time-period limit values of the conductor are exceeded, first the electromechanical switching unit is opened and then the electronic switching unit is blocked.