Patent GB-470047-A (GB)
Title: Improvements in or relating to multipole automatic electric circuit breakers
IPC: H01H71/10
Filed: 1936-08-25
Abstract: 470,047. Electrically-released switches. SQUARE D. CO. Aug. 25, 1936, No. 23332. Convention date, Feb. 18. [Class 38 (v)] Springs, arrangement of; bases and cases; handles; indicators.-A multipole circuitbreaker comprises a plurality of floating members carrying contact surfaces adjacent to one end adapted to co-operate with fixed contacts, and current-responsive latching means for the opposite ends of said members, said latching means releasing all the floating members upon occurrence of an overload through any pole of the breaker to separate all said contact surfaces from the fixed contacts. The base 1 is provided with partitions 5 separating the poles, which partitions are cutaway adjacent the handle 36 and arranged in line with the terminal-separating flanges 4. The parts 4, 5 are slotted at 76 to cooperate with slotted fibre end-closures 73, 74 arranged under the metal cover 75. The movable contact 24 of each pole co-operates with a fixed contact 16 on a connector 14, and is itself carried at one end of a bar 21, the opposite end of which carries a latch surface 27 co-operating with a latch surface 28 pressed out of a latch-member 47. The members 47 are all carried from a shaft 45 rotatable in the side walls of the base 1, and each has a turned-up end 48 maintained by a spring 52 against a bimetal strip 49, which is connected at 51 to'the appropriate bar 21. Each bar 21 is notched at 22 and passes through slots 18, 19 in the unequal depending legs of a member 17, which is guided for rectilinear movement in the base and maintained by a spring 23 against the bar 21. The handle 36 is fast on a shaft 34 and provided with an operating cam-surface for each pole, the individual surfaces being separated by cutaway parts 40 which enable the parts to clear the partition 5. A spring 43 maintains the handle in proper relation to the members 17 in the on position. To effect manual opening from the Fig. 2 position, 36 is rotated clockwise to depress 17 and rotate 21 about the latch surfaces 27, 28 as pivot. In the open position the flat surface 41 of the handle engages the member 17 and holds it against the action of the closing spring 29, which, when the handle is restored to the Fig. 2 position, recloses the switch. On overload in one pole, the strip 49 in that pole rotates member 47 clockwise to disengage 28 from 27, and due to the surface 71 on the bar 21, ensures the movement of the other bars 21 to the released position under the action of the springs 29, Fig. 4. In this position the handle is rotated beyond the normal " on " position and so gives an indication that the switch has been tripped. To reclose, the handle is rotated clockwise right over beyond the off position to cause the surface 42 to depress the bar 21 so far as to relatch it, in which action the bar pivots about notch 22 and, at the contact end, about the base. Release of the handle allows spring 29 to restore the parts to the normal off position, from which reclosure is effected by the handle as already described. Separation of the contacts takes place in an arc chamber having a fibre liner 25. Connectors 14 have depressions 13 over which the tops of metal sleeves 12 are spun, and terminal studs 15 are threaded into the sleeves 12. Connectors 54 are similarly attached to metal inserts 56 having studs 57 extending therethrough, on to which are threaded nuts 59 with intervening cup-shaped members 58. Inside the case the connectors are bent up and the centre parts pressed out at 65, to which parts the strips 49 are secured. The outer limbs of each connector are bent over at 68 and between the limbs a block 66 with adjusting screw 67 is arranged. The connector is applied to the base by slipping it from above into vertical notches 64 in the sides and partitions 5. Fig. 7 shows a modified arrangement of the latch members 47 and shaft 45, whereby all strain is removed from the bimetal strips once release has occurred. The arms 87 are rigidly attached to shaft 85 and biassed by spring 89 in a counterclockwise or latching direction. The latching surfaces 91 are continued into a projecting surface 92, which is engaged by the bar 21 in the tripped position to produce a further movement of the latching member, the latter being also held clear of the strips 49.