GB711881A - Improvements in and relating to electric circuit breakers - Google Patents

Abstract

711,881. Automatic circuit-breakers. MECHANICAL PRODUCTS, Inc. May 5, 1952 [Feb. 7, 1952], No. 11317/52. Class 38(5) In an overload released circuit-breaker held closed by engagement of a bimetal latch with an abutment, the latch being serially connected in the controlled circuit and carried by the circuitbreaker resetting plunger, screw means is provided on the plunger to engage the latch and adjust the amount by which it engages the abutment and thus accurately determine the tripping-current of the breaker. The breaker shown, which embodies several of the features of the circuit-breakers disclosed in Specifications 669,656, 709,717, 709,767 and 711,802, comprises a resetting plunger 16 composed of axially-aligned insulating blocks 14, 18, 20, held together by a central tie-screw 22 screwed at 28 into the block 20, the screw head 24 lying against an annular ledge 26 formed in the block 18. A U-shaped bimetal latch 44 engages an abutment 34 on a fixed block 21 in which the plunger 16 may slide, the latch 44 being connected to form a unit with movable contact-carrying arms 12 and a pair of guide fingers 40 (Fig. III, not shown) which slide over a surface 42 of the block 21. The unit 44, 12, 40, is slidably mounted in the plunger 16 and is moved by springs 38 to open the contacts 10 upon disengagement of the latch 44 from the 'abutment 34. To adjust the position of the latch on the abutment a screw 46 provided in the plunger block 14 engages the inside of the latch and has a head 50 accessible between the fingers 40. The screw 46 passes through the tie-screw 22 and serves also to lock the latter. A casing aperture 52, normally closed by a screw plug 56, gives access to the screw 46.