GB242664A - Improvements in or relating to electro-magnetic cut-outs - Google Patents

Abstract

242,664. Stotz Ges. Abteilung der Brown, Boveri, et Cie, Akt.-Ges. Nov. 8, 1924, [Convention date]. Automatic circuit-breakers; springs, arrangement and disposition of; arc-rupturing devices.- Relates to automatic cut-outs of the kind provided with current-carrying spring contacts between which is inserted an insulating barrier. As shown in Figs. 1 and 2, current normally passes through the manually-engaging spring contacts 7 and through a solenoid 3. The solenoic has a core consisting of magnetic plates 4 between which is secured an insulating barrier 5 adapted to be moved between the contacts 7 or attraction of the core by excessive current in the solenoid 3. To ensure quick breaking of the circuit, the core is connected by links 18 to one end of a lever 10, which is pivoted at 12 and has springs 14 connected between its other end 17 and a fixed point 15. The arrangement is such that the initial attraction of the core 4 moves the springs over the dead centre into a position in which they can quickly complete the movement of the member 5. To deal with small overloads of long duration a thermal release is provided consisting of a bimetallic strip 8 fixed at one end and bearing with its free end on the lever 10, a heating coil 9 included in the cut-out circuit being arranged near to the strip. To reset the cut-out a spring-controlled push button is depressed, a notched projection 26 of the button engaging the upper end of the barrier 5, but the circuit is not completed until the button is released and returned by springs 25, so drawing the insulating projection 26 from between the contacts 7. To indicate the operation of the cutout a coloured pin 28 is arranged to project through a hole in the push-button when the barrier 5 is raised. A magnetic blow-out action is produced by placing the coil 3 beneath the contacts 7. In a modified form, Fig. 6, in which the circuit is broken simultaneously between two series-connected pairs of contacts the arcs between them are blown out as shown in opposite directions.