Patent GB-248883-A (GB)
Title: Improvements relating to automatic electric circuit-breakers
IPC: H01H71/52
Filed: 1925-01-21
Abstract: 248,883. Johnson, E. M., Juhlin, G. A., Thompson, W. H., and Metropolitan-Vickers Electrical Co., Ltd. Jan. 21, 1925. Automatic circuitbreakers with compound movement. A circuitbreaker of the loose handle type comprises two arms pivoted together, one carrying the contact bridge-piece and the other co-operating with a holding or trip device, a manually operated device arranged to move the second arm so as to be held by the holding device while restraining the first arm from moving the bridge piece into engagement with the fixed contacts, and means, operative after the arms have been released from the manually operated device and dependent for action on the position of the second arm, to cause the first arm to move the bridge piece into engagement with the fixed contacts. In the form shown in Figs. 1-3, an articulated lever 1 comprises arms 2, 3 connected by a knuckle joint 4 at the axis 5 about which the lever 1 as a whole pivots. The joint comprises lugs 6, 7, connected by a spring 8, and a shoulder 9 limiting relative movement between the arms in one direction. The arm 3 is connected by a tension spring 10 with a fixed part 11 and pivoted about a fixed axis 17 is an operating lever 18 having arms 19, 20 co-operating with arms 2, 3 respectively. To close the breaker, the lever 18 is turned counterclockwise to move the arm 3 until an armature 15 thereon engages and is held by the electromagnet 16 constituting the automatic trip device. During this movement, the arm 2 is prevented by the arm 19 from moving, so that the spring 8 is tensioned and, when the lever 18 is rotated clockwise. moves the arm 2 to close the breaker. In this position, Fig. 3, the spring 10 is tensioned, so that if a fault occurs and deenergizes, the magnet 16 either during closure or at any other time, the lever 1 will be moved by the spring 10 to open the circuit. In the form shown in Figs. 4-6, the lever 21 comprises arms 22, 23 pivoted respectively about a fixed fulcrum 24 and a pivot 25. The arm 23 carries a cam surface comprising a projection 31 and depressions 32, 33, is slotted at 34 to engage the fulcrum 24, and is connected by a spring 35 with a fixed part. A hand lever 36 is pivoted about the fulcrum 24 and carries a roller 37 co-operating with the cam surface. The breaker is open in Fig. 4 with the fulcrum 24 at the left-hand end of the slot. and the side of the arm 22 projecting beyond the depression 32. To close, the handle 36 is turned counterclockwise, bringing the roller into the depression 32 and moving the arm 22 so that the armature 26 engages the magnet 27 and the spring 35 is tensioned. The handle is then turned clockwise to move the roller past the projection 31, whereupon the spring 35 projects the arm 23 to close the circuit. The spring 35 is still in tension, ready to open the breaker in the event of a fault. Instead of the contacts shown, a single contact block may be employed, and the invention is applicable to single or multi-pole breakers operating in gaseous or liquid media. According to the Provisional Specification, the electromagnet may be replaced by a trigger or the like.