Patent GB-580972-A (GB)
Title: Improvements in or relating to electric circuit breaking apparatus
IPC: H01H71/02
Filed: 1939-01-27
Abstract: 580,972. Electromagnetic switches; switch bases and cases. DAVIDSON, G. W., and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. Jan. 27, 1939, No. 2927. [Class 38 (v)] A remote-controlled, double-pole, D.C. circuitbreaker, suitable for use on board ship where a number may be arranged side-by-side in restricted space, comprises a pair of s.p. breakers 7 mounted one behind the other on a plate 8 hinged on a horizontal axis 9 parallel to the back of the enclosing casing 1. The terminals are connected to the conductors 3, 4 of, for example, a ring main and to outgoing loads 5, 6 by means which can be readily released to allow the plate to be swung forward for access to the apparatus carried thereon. The top of plate 8 is in the form of a circular arc with pivot 9 as centre, and a similar arc is formed on the adjacent lower edge of a plate 14 to which an upward extension of plate 8 is normally screwed. Conductors 3, 4 are connected by the arms 20 of muff connectors 23, 24 and by conductors 27, 33 to a pair of screws and nuts 30, 31 arranged one behind the other, and from these connectors 38 lead to a further pair of nuts and screws 39, 40 and thence to the overload coil 37 for each pole. A lead is taken from the lower end of each coil 37 to the fixed main contact 43 of each breaker, the circuit then traversing the bridging contact 48, lower contact 44 and muff connector 55 to lead 5 or 6. A closing and holding solenoid 13, mounted on the lower end of plate 8, has a plunger 59 and throwoff spring 58 acting through link 60 on a toggle 61, 62 connected by a bar 64 to the contact-arms 49 of the two poles. In order to remove the plate 8 from the casing 1, the connectors 55 are loosened, and the connectors 38 are together slid down so that their forked upper ends are free of the screws 30, the screws 40 engagaing in closed slots in the connectors to allow of this. Each coil 37 carries a pair of plungers of D-section adapted each to open a contact in the circuit of solenoid 13. The plunger 79 is controlled by a spring 85 and is instantaneous in operation, whereas 78 is connected by a lever 86 to a time-delay device 90, the pivot 87 being mounted on a rack 88 which engages with an adjustable pinion 91a. In order to allow independent adjustment of the two coils, the solid shaft 93 of the pinion of the rear coil passes through the hollow shaft and pinion of the front coil to an adjustment device at the front of the casing 1. Means are also provided, Fig. 2 (not shown) whereby the muffs 23, 24 and hence the polarity of the two breakers may be changed over. The closing solenoid is energized directly under control of a hand switch having a central and two side-positions, one of which is engaged to shortcircuit an economy resistance and enable the breakers to be closed, whereas the other is engaged to short circuit the solenoid and allow the breakers to open. In a third operative position the hand switch is connected to a remote switch of a similar character, Fig. 4 (not shown). A fuse may also be provided in the casing, and the Specification refers also to emergency manual closure and retaining by a latch independently of the tripping means. Arc-rupturing devices, contacts.-Conductors 76, 75 connect the fixed main contact 43 to a fixed arcing contact, Fig. 3 comprising a block 65 which is carried in a channel-member 71 and urged outwards by spring 73. When the cooperating block 66 on arm 49 is moved away, the lower pin 74 on the block 65 first engages the lower abutment 72 on 71 to separate surfaces 52, 53 and then the upper pin 74 is arrested by the upper abutment to separate the arcing- surfaces 68, 69, the arc being blown on to horns 76, 77 in an arc chute 54 of the character described in Specification 275,216, [Class 38 (v)].