Abstract: There are arranged at a magnetic trigger for a selectively operative switch, a plunger-type armature, a pivotable armature and a tripping device. A plunger of the plunger-type armature acts directly upon a movable contact of a pair of contacts and the plunger-type armature is actuated using a magnetic coil or winding when the current flowing through the magnetic coil at least corresponds to a predetermined threshold current for opening the contacts. A pivotable armature is actuated by the plunger-type armature and redirects the magnetic return flux. The tripping device acts upon a switch lock mechanism and is switched into or out of the magnetic return flux by the plunger-type armature. The degree of overlap between pole shoes of the pivotable armature and of the tripping device is preselectable by an adjusting screw. There is thus realized a current-dependent, selective tripping of the switch lock mechanism.