Patent GB-398213-A (GB)
Title: Improvements in or relating to circuit breakers
IPC: H01H33/18
Filed: 1932-03-01
Abstract: 398,213. High-tension switches; arcrupturing in switches. WHITNEY, W. B., WEDMORE, E. B., and BRITISH ELECTRICAL & ALLIED INDUSTRIES RESEARCH ASSOCIATION, 36, Kingsway, London. March 1, 1932, Nos. 6242, 12910, 17314 and 17315. [Class 38 (v).] A circuit-breaker comprises a pair of arcing electrodes, each of which forms a passageway, or part of a passageway, serving as a vent for arc-products, the adjacent ends of the passageways forming during arcing the opposing walls of a wide, disc-like region to direct a blast of fluid from the periphery thereof inwardly towards the arcing surfaces. Means are provided for producing the blast from outside the electrodes, wiping the arcing surfaces, flowing into the adjacent ends of the passages and escaping therefrom, and means independent of the blast are provided to hinder the movement of the arc roots outwardly from the centre of the region between adjacent ends of the passages. An inlet 20 admits fluid under pressure to a container 10 having a fixed contact 32 with a conical surface 33 and a movable contact 30 which has a conical surface 31 and is slidable in the bottom of the container to make and break contact. When 30 is lowered, fluid enters the space between the contacts and escapes through the passages in both of them. Both contacts are formed into segments by means of cuts so that the current flowing to and from the arc must enter a segment from its periphery, so setting up a magnetic field which keeps the arc and its roots from expanding outwardly. In another form, Fig. 2 (not shown), the tubular contacts taper towards one another and have insulating guides on their ends to form between them the disc-like space. In Fig. 3, a hollow contact 52 carries a guided spider 53 urged in the off direction by springs 56 so that, when the contact 63 is lowered, the contact 52 drops and separates contacts 57, 58. When spider 53 engages the segments 61, a box-like contact 59 is brought out of contact with the casing top the top of the electrode 52 preferably just protruding out of the top of the box. The latter and the top cover contact are formed in segments to confine the arc, as in Fig. 1, the cuts being filled in with insulation projecting over the. surface to prevent shorting of the segments by metal beads. The contact 63 separates from the fingers 62 after the lapse of a cycle from the separation of 59 from the top cover. Inserts 67 of magnetizable material are provided as disclosed in Specification 398,297. In Fig. 7, the arcing electrodes 70, 67 are fixed, and the latter is in the form of a shell comprised of four sectors held.by a spring 73 with an insert 74 of magnetic material for preventing the arc's being drawn in the shell. The movable contact 71 has ports 72. In Fig. 8 (not shown) two movable electrodes pass through apertures in two plates to which are connected fingers which slidingly engage the movable electrodes for at least a cycle so that the arc remains between the two plates. A serially-connected, spirally-wound coil may be placed round the fixed contact to cause the arc to rotate about the axis of the latter, a segmented moving contact being employed for co-operation therewith, Fig. 9 (not shown). To ensure a constant velocity of blast-fluid past the opposing faces of the electrodes, those faces may be nearer together at the periphery than at the middle, or may have insulating material of suitable shape for this purpose mounted on them, Fig. 10 (not shown). In Fig. 11, fluid is led through the lead-in 102 to four pipes 100 and both arcing electrodes 104, 105 are fixed. The former has a grid 12 to confine the arc and the latter a seating 115 for a shoulder 114 on the movable contact 103 to keep the container normally closed. When the contact 103 is withdrawn, flaps 106 close over it to drive out the arc products by way of cooling grid 107. The bridge-piece' 109 engages the fingers 108 which are shown as staggered to compensate for the different diameters of the contact 103. When the embodiments shown are used with a liquid blast, they may be wholly or partly filled with liquid, or immersed in liquid in a tank. Specification 398,249 is referred to. The first Provisional Specification refers to Specifications 278,764, 330,616, [both in Class 38 (v), Electric switches &c.], 366,998, 375,309, and 378,493.