Patent GB-448674-A (GB)
Title: Improvements in and relating to automatic reclosing circuit breakers
IPC: H01H75/04
Filed: 1935-12-20
Abstract: 448,674. Switches, partly electromagnetic. BRITISH THOMSON-HOUSTON CO., Ltd.. Crown House, Aldwych, London. Dec. 20, 1935, No. 35370. Convention date, Dec. 24,1934. [Class 38 (v)] Oil switches.-An automatically-reclosing circuit-interrupter has its movable contact actuated under a bias to the circuit closed position after each opening operation, and a member is actuated to a limited degree within a predetermined range of movement at each reclosure and, after a given number of consecutive reclosures, is moved to a restrained position for holding the movable contact in open circuit position. In Fig. 1, the contact 6 is normally urged into engagement with contact 5 by a spring 18 bearing against a bar 16 which, by engaging a slot 17<1>, serves to guide the extension 17 of the armature 8 carrying the contact 6. Pivoted to 17<1> at 21 is a ratchet member 20 normally urged by a spring 25 so that its teeth 22 engage a ratchet wheel 23 on a shaft 24, the form of the teeth being such that 23 is only rotated on the downward, reclosing stroke of the member 20. A weighted and guided member 26 carries a rack 27 engaging a pinion 28 on shaft 24. An oscillating escapement device 35, 36 is driven from the shaft 24 through gearing 32, 33. When on overload the series-connected solenoid 9 raises the armature 8, the circuit is broken, preferably in a body of oil, the level of which is shown at 4, and the member 20 is raised to bring its teeth 22 into mesh with the wheel 23. The subsequent descent of the contact 6 under the action of spring 18 is retarded initially by the escapement until the teeth get out of mesh, whereupon a rapid reclosure occurs. During the descent of 20, the member 26 is raised, and when the teeth go out of mesh, returns under gravity subject to retardation by the escapement. If the fault persists, however, a second opening and reclosure causes the member 26 to be raised further, and when its part 29 strikes the adjustable stop 30, further movement is prevented, so that a subsequent opening causes the switch to be locked open by the engagement of teeth 22 with wheel 23. Manual means are then employed to disengage the teeth and permit reclosure of 5, 6 and return of 26. In the commercial form shown in Fig. 2, the insulating casing 1 is replaced by a steel oil-tank and the armature 41 is slidable on contact rod 42 to effect high-speed separation and lowering of the minimum pick-up current. An extension to rod 42 comprises a pair of spaced plates 44 to which is pivoted at 47 the ratchet member 45 urged against the ratchet wheel 51 by a spring 50 bearing on a member 46 which is pivoted to 44 at 49. Member 46 is pivoted at 52 to an arm 53 pivoted at 55 and carrying an arm 54 exteriorly of the casing, a spring 56 biassing the arm 53 clockwise and hence closing the contact 6. By means of pole 57 the arm 54 can be rotated to engage the part 61 of a latch 58 pivoted at 59 outside the casing, this engagement causing clockwise rotation of 58 so that the arm 54 engages the part 60 of the latch and locks the switch open. This lock can be removed by pressing the latch part 62 with the pole, the arrangement thus providing a visual indication of the switchcondition. The escapement 67, 68 is driven by a gear-wheel 65 on the shaft 63 carrying the wheel 51, the shaft 63 being normally urged in a counterclockwise direction by a spring 64 anchored at 641. The limit means is a pin 69 on wheel 65 engaging a pin 70, the action being similar to that described in connection with Fig. 1, with the added feature that the indication is given by the position of 54, which is pushed upwards by the pole 57 to release the ratchet means and released to allow reclosure of 6. The break-chamber 87 is formed in an insulating cylinder 80 which is apertured at 88 and secured at 801, 80<11> to the cover 73 having lugs 79 for suspending the unit as a whole from a pole.