A TRIP DEVICE FOR AN ELECTRIC SWITCH

An improved trip device for an electric switch, comprising a yoke (1), a permanent magnet (5) immovably positioned with respect to the yoke (1) and a movably supported armature (6) forming a first magnetic circuit, in which the armature (6) being able to assume a first position under the influence of the magnetic field of the permanent magnet (5). A magnet winding (13, 14) and spring means (12) being provided for causing the armature (6) to assume a second position in response to the magnetic field generated by an electric current, flowing during operation in the magnet winding (13, 14). For adjusting the treshold value at which the armature (6) is moved to its second position, a second magnetic circuit in the form of shunt means (16) interacting with the yoke (1) and the permanent magnet (5) being provided. The magnetically effective surface area of the shunt means (16) being smaller in the vicinity of the section (19) thereof which interacts with the yoke (1) than in the vicinity of the section (20) which interacts with the permanent magnet (5).