Improvements in and relating to thermally operated switches or circuit-breakers for protecting electric circuits

摘要

270,540. Calor Elektrizitõts-Akt.- Ges., and Dreyer, O. Aug. 23, 1926. Automatic circuit-breakers. - A switch shaft 7 carrying a contact member 10 is rotated into the closed position against the action of a spring 16 by a handle 15 and is there locked by a device 17; upon overload a heating coil 26 causes the release of a member 24 normally held fast within the coil by fusible metal, and the member 24 is driven by a spring 22 to cause the release of the locking device 17 and is then automatically returned to its original position by an action depending on the opening movement of the switch. In the form shown, the spring 22 is stressed by a cam 23 on the shaft 7, and when the fusible metal melts forces the member 24 upwards against the action of a weaker spring 27, a rod 21 connected to the member 24 simultaneously moving upwards a member 19 and tripping the latch 17. The shaft 7 then revolves under the influence of the spring 16 and the cam 23 being removed from the spring 22, the spring 27 is able to return the member 24 to its original position, where it is resoldered. In a modification, the member 24 is acted upon by coil springs above and below it, the lower stronger spring being put out of effective action when the switch opens. In other modifications, one spring only normally acts on the member 24. and the return movement is in this case effected by a cam or arm on the shaft 7, which under the influence of the spring 16 drives the member back.