Patent GB-452146-A (GB)
Title: Improvements in or relating to electric circuit-breakers
IPC: H01H33/75
Filed: 1935-01-16
Abstract: 452,146. Liquid-blast switches. REYROLLE & CO., Ltd., A., Hebburn-on-Tyne, and ALLAN, A., Cragside, Ashleigh Grove, Tynemouth. Jan. 16, 1935, No. 1462. [Class 38 (v)] In a liquid-insulated A.C. switch of the kind having an arc control device comprising an enclosure through which the moving contact is drawn and in which a relatively high pressure is produced by the arc, so that the compressed liquid, vapour, and gas within the enclosure constitutes a deionizing fluid or blast to force the arc gases through vents in the enclosure which are laterally disposed with respect to the arc path, the main structure of the device is divided longitudinally into two separate parts, each in the form of an integral solid insulating block held together laterally by bolts or other fastening devices. In Figs. 1, 3, solid blocks A, A<1> of arc-resisting insulating material, as fibre, are shaped by machining out of a solid block to form, when fitted together, a central passage, the upper part B of which is closed by a plate C<1> carrying spring-controlled, fixed contact arms C, C<2> co-operating with the movable contact E. The lower part B<1> is closed by an insulating throat washer D, loosely mounted in a groove A<3> in the blocks, and constitutes the arcing enclosure. Contact E may be a circular rod but is shown as a flat bar with an arcing tip E<1> co-operating with a pair of extended contact arms C<2> next the inwardly-tapering vents. The latter are radially arranged with respect to the contact E, as shown at F, F<1> in Fig. 3, and may be formed by milling the adjacent surfaces of the blocks A, A<1>, or of one of the blocks, in which case the passage B<1> is displaced to one side. The upper vent F is deeper or wider than F\ and where more than two vents are provided, only the top three, say, are graduated in section, the rest being of the same section. Instead of a smooth wall, the passage B<1> may have grooves cut in it to form oil pockets, or a removable member formed with pockets may be arranged in the passage. Metal straps or bolts G may secure the blocks A, A<1> together. In the closed position, the contact E closes the vents and when an arc is drawn between C<1>, E<1> in opening circuit, the pressure rises in B<1> and at currentzero a blast of deionizing fluid sweeps across the arc path and out of such vents as have been opened by E. In a double-break switch the arc-control devices are arranged so that the flow of current acts electrodynamically on the arcs to bring them close to the vents, which action may be supplemented or replaced by the use of magnetic material such as laminµ embedded in the ridges between the vents. The latter are thus sealed by the arc in the manner disclosed in Specifications 435,250 and 435,308. Where the sealing by the contacts might result in setting up pressure in the block during circuit closing, the throat of the upper vent may be set back slightly while still allowing of sealing by the arc, or the seep-hole may be enlarged for this purpose. The vents may be formed in a separate removable member or members located between the main parts, and vent throats may be formed in a removable member of the character disclosed in Specification 450,405. Other insulating materials which may be used are hard wood, sindanyo, and the materials known under the Registered Trade Marks " Bakelite " and " Beetle," whereas slate and " bakelized " paper may be used for side plates and vitreous materials, as porcelain, for the separate vent members. In Figs. 6-8 (not shown), the vents are formed by inserting baffles in grooves in side plates, and in Figs. 9, 10 (not shown), two blocks are arranged so as to provide offset vents alternatelyoppositely directed from the plane of the vent throats and movable contact, an arrangement which provides better distribution of the arc gases in the liquid of a double-break switch. Alternately-oppositely directed vents P<1>, P<2> are formed in a block P, Figs. 11, 13, assembled between side plates Q, Q<1>. The block P is V-shaped to provide a recess S closed by a back plate R. The movable contact rod T passes through a throat washer V<1> in the base plate V and in the closed position is located close to the vent throats, one U<3> of the fixed contact blocks U being extended so that the arc is formed next the vents. The control device may be mounted in position by means of a bayonet joint, and a pair of arcuate control devices may be arranged to co-operate with a horizontally-mounted contact rotatable about a vertical axis. Specification 366,998 also is referred to.