Patent GB-462677-A (GB)
Title: Improvements in or relating to electric distribution switchgear
IPC: H01H1/20
Filed: 1935-09-12
Abstract: 462,677. Switchgear structures. REYROLLE & CO., Ltd., A., and CLOTHIER, G. D. Sept. 12, 1935, No. 25326. [Class 38 (v)] In distribution switchgear, the individual phases or poles of the bus-bars lie one behind the other approximately in a plane and the individual phases of the connections to each distribution circuit lie one behind the other approximately in a plane at right angles to the bus-bar plane. The connection of each phase or pole includes switches which can be operated in readiness for bodily withdrawal of a structure carrying contacts of the switches co-operating with contacts which are connected to the busbars and circuits and are left in position in the switchgear when the structure is withdrawn. Figs. 1, 2 show one form applicable to a 3-phase, 4-wire system having three panels, one for each of three distribution circuits, housed in one box-like casing with separating partitions A<3>. The latter support insulating blocks C on which are mounted strips B2 which are clamped at B<3> to the phase bus-bars B. The cables enter through cable boxes D and connections are made to lugs D<2> connected to strips D<3> on insulating blocks C<2>. The neutral cable is connected to lug D<4> which carries a strip D<5>, and the neutral bus-bar B<1> carries a strip B<4>, the two strips being either interconnected by a removable link K or provided with a switch arrangement similar to that for the phase conductors. Strips B<2>, D<3> constitute fixed main and isolating contacts and co-operate with contacts H, H<1>, which are preferably interconnected by cartridge fuses H<4> and are mounted on insulating blocks on a carrier J. Contact-pressure is ensured by means of a stud and spring arrangement J<1>, J<2> between the carrier J and its supporting frame G, which is slotted at G<1>, G<2> to co-operate with the ends of cranks F<2>, F<3> on shafts F, F<1> rotatable in end-wings E<1>, E2 of a tray E. To open the circuit, shaft F is rotated clockwise to separate contacts H, B<2>, and then F<1> is rotated anticlockwise to separate H<1>, D<3>, a pin or pins G3 on the frame G co-operating with a slot or slots E<3> in the tray E to ensure correct sequence. When both switches are open, the tray E can be slid out on rails A<5>, A<6> to permit access to the interior of the casing, safety being ensured by means of a separate metal sheet applied to the rails and having a projection covering the bus-bars. The front of each panel has a door E<4> carried by the tray and apertured to enable operating handles F<4>, F<5> to be applied, the latter being preferably so shaped that it can be used for withdrawing the structure. - The door may be removable from the tray either before, or after, withdrawal, and the tray can be replaced and operation of the switches observed. Openings may be provided in the side walls of the casing to facilitate addition of panels by inserting therein the ends of bus-bars of a neighbouring casing, as shown dotted in Fig. 1. Each panel casing may, if desired, comprise a separate structure, a number of such being then bolted together side by side. Arcing barriers may be mounted between the phases in larger sizes of gear, and adapted to be lowered clear of the main fixed contacts to facilitate withdrawal of the structure. In Fig. 6, the strips N2, P<2> in the phases serve as fixed contacts for two isolating switches, the movable contacts Q<2>, Q<3> of which are in the form of spring- controlled rollers mounted in slotted bearings and are adapted, when their shafts Q, Q<1> are rotated into the position shown, to connect the strips N<2>, P<2> with a cartridge fuse S and block U, respectively. The lower end of S is bolted to a strap T on insulating blocks O<4>, 05 on the tray M. The main switch comprises a fixed contact R<1> on the strap T and a movable contact R<2> both being provided with arc horns and mounted in an arc shoot R<6>. Contact R<2> is connected to block U by a lead R<7>. The contacts R<2> of the phases are mounted on a shaft R operable by a solenoid V through a lever V<1> and free-handle device V<2>, which is capable of being tripped by a coil V<3> energized by a current transformer V<4> on strap T. The shafts Q, Q<1> are interlinked by the system W ... W<4> carrying an interlocking stop W<5> for co-operating with a cam R<8> on shaft R. The shaft Q<1> is operated by handle Q<4> and carries an arm Q<5> engaging behind the wall L<1> to prevent removal of the tray M unless the isolating switches are open. The neutral link is shown at P<5>.