Patent GB-548306-A (GB)
Title: Improvements in or relating to enclosed electric switchgear
IPC: H01H31/32
Filed: 1941-04-02
Abstract: 548,306. Switchgear structures. REYROLLE & CO., Ltd., A., ALLAN, A., and CHRISTIE, J. April 2, 1941, No. 4417. [Class 38 (v)] Each of a number of busbar sections is contained in a busbar chamber and tee-connected over a circuit-breaker to an external circuit. Each section comprises a busbar member from which the tee extends and a switch rod or tube normally occupying a central position connecting the busbar member to intermediate contacts passing through the walls of the chamber and serving to connect the sections in series. The switch rod or tube is longitudinally movable in either direction to break the connection with either intermediate contact while maintaining connection with the other. Preferably each section forms a panel, the panels being side-byside in a row, or in two rows back-to-back, with the busbar sections in line, and, in the case of a two-row ring-busbar, end-connected together. In Fig. 3, each busbar member A' is housed in a chamber B having an end-wall B<SP>2</SP> supporting the intermediate contacts C<SP>2</SP> and a metal bellows B<SP>3</SP> to accommodate temperature changes. The member A' houses a longitudinally-movable rod or tube A<SP>2</SP> which normally connects with both contacts C<SP>2</SP> but is movable to break either connection. A lead A<SP>4</SP> extends downwards to a contact A<SP>5</SP>, the three being in line under the middle busbar and over three similar contacts H for the external circuit. Isolating contact arms E, G are rotatable about conductors E<SP>1</SP>, G<SP>1</SP> into engagement with an earthing contact D', the conductors passing through insulators E<SP>2</SP>, G<SP>2</SP> surrounded by current transformers D<SP>3</SP> in a compartment D<SP>2</SP>, supported in the front wall D<SP>1</SP> of the housing D, and containing sockets for normally engaging plug contacts on the main breaker or breakers F so as to permit removal of the latter for inspection. The isolators E, G may be arranged to open automatically after opening the breakers. Each chamber B has a removable fluidtight cover B<SP>4</SP> for facilitating inspection and removal of parts in the chamber while normally preventing escape of insulating gas or liquid therefrom. For carrying out inspection of the panel, the breaker and isolators are opened and the switch rods A<SP>2</SP> in neighbouring panels disengaged from the contacts C<SP>2</SP> in the end walls of the panel to be inspected, the arrangement allowing the neighbouring panels still to function, Fig. 3. The breaker and either isolator can then be reclosed so as to earth the busbar section or cable. Alternatively, separate earthing switches for the busbar and cables may be provided. In Fig. 5, the busbars are arranged one over the other in chambers J<SP>1</SP> ... J<SP>3</SP> having diagonally-arranged apertures K<SP>1</SP> ... K' to receive insulators P<SP>1</SP> ... P<SP>3</SP> which are fixed in covers O<SP>1</SP> ... O<SP>3</SP> on the truck N and guide isolating-contact rods Q<SP>1</SP> ... Q' which are retractable into engagement with earthing- contacts R' ... R<SP>3</SP>. Each rod is in sliding contact with a conductor leading to the breaker, such conductor preferably consisting of the exhaust pipe S' for the gases of a gas-blast breaker S<SP>2</SP>. The other breaker-terminals S<SP>1</SP> are connected to cable-isolator rods T housed in insulator T<SP>1</SP> and passing through current transformers M' and the rear wall of the truck N, into engagement with cable-contacts L<SP>3</SP> in insulators L<SP>1</SP> in cablechamber L arranged side-by-side. Earthing- contacts T<SP>2</SP> are provided for these rods also. A withdrawable potential transformer U can be run between the wheels of truck N so as to engage cable-contacts U<SP>2</SP>. The first arrangement may have sliding rod isolators and the isolators thereof may be carried by the breaker-unit, whereas the second arrangement may have pivoted arm isolators and the isolators may be on the fixed part of the gear. " Oil-poor " circuit-breakers may be employed instead of gas or air-blast ones. The Provisional Specification refers to Specification 548,307.