Patent GB-526422-A (GB)
Title: Improvements in and relating to automatically reclosing electric circuit breakers
IPC: H01H75/04
Filed: 1939-02-27
Abstract: 526,422. Automatic circuit-breakers. BRITISH THOMSON-HOUSTON CO., Ltd. Feb. 27, 1939, No. 6435. Convention date, Feb. 26, 1938. [Class 38 (v)] A high-speed reclosing mechanism for a circuit-breaker comprises means for opening 'the breaker, energy-storing means for applying instantly a reclosing force to the breaker, and means for releasing the energy stored at a predetermined point in the opening stroke of the breaker for obtaining reclosure thereof. The breaker-operating member B is connected to a floating lever 1 which is connected at one end through a lever 7 and normally-locked toggle 9, 10 to a manually-controllable motor and flyball closing mechanism M. The toggle 9, 10 is' retained in locked condition by a latch system 11, 12 releasable by a trip solenoid 13. The other end of lever 1 is connected to a lever 3 having a fixed pivot 3' and a roller 31 engageable by a trip member 30 for retaining that end of lever 1 in the closed position shown. A bucking winding 38, when energized by a trip relay 40 on overload, shifts the flux of the permanent magnet 36 from armature 37, so allowing the spring 33 to move the armature-lever 34 to disengage the member 30 from the roller 31 and permit clockwise rotation of lever 1 about its left-hand end, so causing the breaker to open. The opening spring S<1> is in compression between a fixed abutment and the collar of a plunger 15, which is pivoted to a lever 17 having a fixed pivot 18 and is connected to lever 3 by means of a toggle 20, 21. The latter is normally restrained by a lever 23 pivoted to the common toggle pivot 22 and having a pin-and-slot connection 23', 25 with a catch lever 24 on which is a roller 26 engaged by a catch 27. So long as the toggle 20, 21 is thus restrained, the spring S' tends to rotate lever 3 anticlockwise. The pin 25 of the catch lever 24 is connected also to a link 29 pivoted at 29' to a lever 28, which has a fixed pivot at 28' and is acted on by the plunger 16 of the automatic reclosing spring S<2>. When the spring S' begins its opening stroke, a lever system 42 .. 44, at a point in that stroke determined by the adjustment means 44<1>, acts through lever 41 to deflect the catch 27 and remove the restraint from the toggle 20, 21 so permitting the spring S<2> to reverse the movement of lever 3 and reclose the breaker. If the fault is a sustained one, the breaker is again tripped open, in this case by the solenoid 13. The change-over from winding 38 to solenoid 13 is effected by the contacts of a time-delay relay 63, which is energized by an abutment 62 on the member B momentarily closing contacts 61 in the previous open-close operation. Thus during the expiry of the time-delay of relay 63, the operation of overload relay 40 energizes the coil 13 over contacts 65, 67. Restoration of supply is then effected by mechanism M under control of the operator. Resetting of the springs S<1>, S<2> is effected by a cam 53 on a shaft 51 driven through suitable means from a motor 50. When the lever 1 is reset after automatic reclosure, the member 30, in resetting, makes at contacts 46 and over the closed limit-switch 47, the circuit of the motor-contactor coil 48. The motor starts and cam 53 is rotated and engages a roller 53' on a pivoted arm 55, which recharges the spring S<1> and, by means of abutment 55<1> on arm 55, also moves an arm 56 to recharge spring S<2>. A spring 58 held in compression by the arm 56 when the spring S<2> is in discharged condition, acts on a lever 57 to hold the switch 47 closed, but when the spring S<2> is being recharged and the force removed from spring 58, the cam 52 acts on the lever 57 to maintain the switch 47 closed. Since the spring 58 is in tension at the end of the recharging operation, the lever 57 is forced to drop into the lowest part of the cam 52, as shown, so opening the switch 47 and applying the brake 60 to the motor by means of spring 59. Specification 484,861 is referred to.