GB735603A - Improvements in or relating to automatic electric switches with overload release - Google Patents

Abstract

735,603. Automatic circuit-breakers. SIEMENS-SCHUCKERTWERKE AKT.-GES. July 24, 1953 [July 30, 1952], No. 20620/53. Class 38 (5). An automatic circuit breaker can be manually opened and closed by a slidable hand operating member which is coupled with a pawl slider carrying two pawls, one of which can lock a contact-operating slider in closed position and is controlled by a releasing slider, whilst the other pawl engages a fixed abutment in the closed position and is controlled by the contactoperating slider. Fixed contacts 1, 2 are arranged to be bridged by a movable contact 3 on a carrier 4 which is biased upwards by a spring 6. The contacts are held closed by the contact-operating slider 24 which has an arm 26 which is engaged by the first mentioned pawl 19. The latter is pivoted on a slider 18 together with a pawl 20 and has a part 22 engaging a recess 23 in the hand operating member 16 so as to couple this member with the pawl slider. The pawl 20 has a part 20<SP>1</SP> engaging the fixed abutment shown at 33 and each pawl has an arm 1911, 20<SP>11</SP> respectively engaging apertures 30, 27 in the releasing slider 25 and the slider 24. The arms 19<SP>11</SP>, 20<SP>11</SP> are urged against the edges of the apertures by springs 32, and the slider 25 is normally held in the Fig. 1 position by a bimetal strip 9 having a heater and in series with the contacts. When bimetal 9 deflects, the slider 25 is released and is moved down by a spring 29 so that a sloping part 31 of aperture 30 forces the pawl 19 clockwise to release the arm 26 and slider 24 to open the contacts. The upward movement of slider 24 causes a sloping part 28 of its aperture 27 to tilt pawl 20 counterclockwise to disengage part 20<SP>1</SP> from the abutment 33, so as to allow the spring 29 to raise the member 16 into an intermediate, indicating, position, Fig. 2 which is determined by the arm 19<SP>11</SP> abutting the upper end of aperture 30. The contacts will thus still open even if the member 16 is held down by hand (Fig. 3, not shown). Downward movement of slider 25 also allows contacts 12, 13 to close an indicating circuit. To reclose the breaker, the member 16 is pulled out from the Fig. 2 position, the arm 19<SP>11</SP> of the pawl 19 thereby raising the slider 25 which is relatched by the bimetal strip 9. Subsequent depression of the member 16 then causes arm 19<SP>1</SP> to engage and depress slider 24 to close the contacts. The contacts may be opened manually by pulling the member 16 out, the movement of arm 19<SP>11</SP> along aperture 30 releasing the slider 24 and opening the contacts. The parts are arranged in a slender rectangular casing having recesses and projections to guide the parts.