Patent GB-481407-A (GB)
Title: Improvements in or relating to electric switches having automatic overload tripping or release mechanism
IPC: C10M159/20
Filed: 1937-08-03
Abstract: 481,407. Automatic circuit-breakers. SIEMENS - SCHUCKERTWERKE AKT.- GES. Aug. 3, 1937, No. 21350. Convention date, Aug. 3, 1936. [Class 38 (v)] A switch having automatic overload tripping or releasing mechanism including a pivoted catch lever co-operating with a movable detent or stop which is actuated to effect tripping, has a member of the switch operating toggle pivoted on the catch lever, and the length of the catch-lever bearing or the distance between two bearing parts of the lever is greater than the effective length of the leverarm perpendicular to the bearing axis. The drawing shows a screw-plug switch having a tripcoil 4 with plunger 6 and push rod 8, a bimetal element 16 with adjustable screw 41, and a mechanical-release batton 15. The catch lever 24, Fig. 4, is provided with two bearing points on a pivot 23 and embraces two side-plates 17 housing the mechanism. The detent lever 37 is similarly pivoted at 38 and embraces plates 17, and is further provided with an insulating piece 42 adapted to be engaged by screw 41 when element 16 flexes to the left. The rod 8 and press-button 15 engage a lever 40 which is pivoted at 39 and takes in a slot in the lever 37. The movable bridging contact 12 is positioned between insulating members 31, Fig. 6, on the ends of arms 29 forming with arms 28 a two-part lever, which is held extended by means of a spring 30 wound round their common pivot 49. A toggle 25, 27 is pivoted to lever 24 at 46 and to arms 28 at 44, and its common pivot 26 takes in a slot 32 in an extension 33 of the operating-button 13 which is guided by plates 34, 35 riveted in plates 17. When the lever 37 is rotated anticlockwise, a spring 43, Fig. 6, around pivot 49 rotates lever 29 to move contact 12 " off,'' and at the same time slides toggle 25, 27 to the right. During this movement, a further spring 45, Fig. 6, acts on lever 27 to raise the pin 26 and button 13 to the open position against guide 34, which movement also restores lever 24 into engagement with detent 37. To reclose, the button 13 is pushed down to carry the pivot 26 below the line of centres, where it is arrested by guide 35. Owing to the arrangement of the pin 26 and slot 32, the switch cannot be held closed on overload. The coil end-plate 19, plates 17, and the base-plate 18 are secured by tubular rivets 20 to a ceramic intermediate body 9 in a chamber in which the contacts are housed. The cover 14 is secured to the body by screws 21 passing through the tubular rivets 20 into nuts located in recesses in the cover. The arms 29 pass into the contactchamber through slots, the ends of which are defined by projections 48 which absorb the opening impact of the mechanism. Arms 28. 29 can be replaced by a single rigid lever and the spring 30 replaced by one mounted between that lever and contact 12. The toggle 25, 27 can be arranged to pass well over the dead-centre position before reaching stop 35 in order to obtain reliable closure of the switch, Fig. 8 (not shown), or the arms 29 could be locked open by a spring-member which is deflected by the button 13 at the end of the closing movement to allow spring 30 to impart a rapid closing movement, Fig. 9 (not shown). The Specification also shows how the invention can be applied to a switch mounted on a flat baseplate with the contacts in a chamber located between a pair of blow-out and trip coils, and an armature that is made of a stamping and moves in a plane parallel to that of the coils and embraces the latter, Figs. 10-13 (not shown).