GB745744A - Improvements in and connected with electric switches or circuit breakers - Google Patents

Abstract

745,744. Automatic circuit breakers. CRABTREE & CO., Ltd., J. A., and WINTLE, T. D. G. Feb. 1. 1954 [Feb. 26, 1953], No. 5364/53. Class 38(5) A push-button tripfree switch, particularly a motor starter provided with overload devices as in Specifications 686,688 and 686,740, comprises a toggle 22, 23 pivoted at one end on a swinging bracket. 32 consisting of a pair of side plates joined by a cross strip 32a and pivoted to a lever 8 by a pin 33, the centre joint of the toggle being connected by a link 20 to a lever 13 which is pivoted at 11a, 19 to "stop" and "start" buttons 11, 12 respectively and to the frame at 14. The other end of the toggle is pivoted to an insulating frame 25 carrying a contact 28 for each phase. the frame being spring-biased to the contact-open position. On overload, units each comprising a bimetal 1 and a heater 1a deflect downwardly into engagement with extension 2b of a trip arm 2 supported in notches 3 in the casing 3a and the turning of arm 2 against springs 3b causes an ambient bimetal 4 secured to arm 2 to engage a ramp 5 on an insulating plate 5a causing the latter to pivot at 5b thereby depressing a part 6a of a spring blade 6. end 6b of which is secured to a metal end plate 10 and the other end 7 of which releases arm 8. Arm 8 pivots at 9 under influence of spring 30 carrying pivot 33 with it. and owing to engagement of strip 32a with a screw 34, pivot 21 rises and spring 30 then urges parts into position shown in Fig 2, the contacts now being disengaged. In the event of failure of spring 30, frame 25 is moved into the "off" position by the movement of the centre point of the toggle to 21b, the toggle arm 23 and bracket 32 thus moving arm 8 to the re-set position. The pressure between end 7 and arm 8 and the position of pivot 31 may be adjusted by screw 34, while the amount of engagement of the two can be varied by moving a pillar 35 in a horse-shoe slot in the plate 10 which causes slot 6d in the blade 6 through which plate 5a passes to be moved vertically. The gap between ramp 5 and bimetal 4 may be varied by adjusting a scale lever 37 pivoted on plate 10 one end of the lever carrying pivot 5b for the plate 5a, the pivot moving in a slot 41 in the plate 10. A rubber cover (Fig.10, riot shown) may be provided for the pushbuttons. Specification 686,739 also is referred to.