GB709947A - Improvements in and relating to automatic electric circuit breakers - Google Patents

Abstract

709,947. Automatic circuit-breakers. BRITISH THOMSON-HOUSTON CO., Ltd. Aug. 16, 1951 [Aug. 16, 1950], No. 19361/51. Class 38(5) [Also in Group XXXVI] The circuit-breaker comprises a hinged armature normally latching a tripping mechanism, a series bimetal element fixed at one end adjacent the hinge of the armature so as to extend parallel thereto, and means for coupling the bimetal and the armature so that the latter is retractable either by warping of the bimetal on a slight sustained overload, or by a heavy overload which produces a magnetic field attracting the armature directly to the bimetal itself. The armature 37 is pivoted at 38 and has (i) a catch 39 engaging the end 40 of a tripping member 21 and (ii) a hook-portion 37<SP>1</SP> around the free end of the bimetal 30 which is secured at 31 to an adjustable plate 35. On a prolonged slight overload, the bimetal 30 bends to the right, Fig 1, carrying the armature with it, thereby releasing the member 21 which pivots counter-clockwise and carries a tension spring 26 over-centre to separate contacts 17, 18 and move the handle 25 to the Fig. 4 position. A lug 19x on a member 23 secured to the handle and pivoted at 24 engages the contact lever 19, which is pivoted at 20 to member 21, to give it a positive start. With a heavy overload, the armature is attracted to release the member 21 by the magnetic field set up by the current in the bimetal itself. The breaker is reset by moving the handle to the right from the Fig. 4 position, a lug 23<SP>1</SP> on the member 23 engaging a shoulder 21<SP>1</SP> on member 21 which is moved clockwise to re-engage parts 39, 40, the contacts being reclosed when the handle is moved back to the Fig. 1 position. The contacts 17, 18 are situated in an are chute 50 leading to a vent 52. The contact 17 is connected to a clip contact 14 . arranged to engage a blade on a panel.