Patent GB-457816-A (GB)
Title: Improvements in or relating to metal-clad electric switchgear
IPC: H02B11/10
Filed: 1935-06-07
Abstract: 457,816. Switchgear structures. REYROLLE & CO., Ltd., A., Hebburn-on-Tyne, and ALLAN, A., Cragside, Ashleigh Grove, Tynemouth. June 7, 1935, No. 16573. [Class 38 (v)] Metal-clad switchgear, suitable for voltages up to 66 kV., comprises the combination with a number of main circuit-breakers controlling a normally-closed ring circuit from which connections to external circuits are teed off at points intermediate the breakers, of an isolating switch chamber controlling each tee point and comprising three contacts normally connected through insulated conductors passing through the metal casing of the chamber respectively to the external circuit and (directly or indirectly) to contacts of the adjacent main breakers in the ring, and a rotary isolating switch member in such chamber co-operating with the three contacts and so arranged that it can be moved to connect together all three contacts or any two of them. The three-phase, oil - immersed breakers A are arranged in a row with the three phases in each breaker arranged one behind the other. An intermediate upper chamber C is arranged between each pair of breakers and a further similar chamber C is arranged at each end of the row, each chamber being partitioned at C<1> to separate the phases, and having a float-operated, oillevel alarm C<2>. The intermediate chambers contain contacts A<4> connected with the fixed breaker-contacts A<2> over conductors in bushing insulators which are provided with metal bellows A<5>, but in the end chambers C, one contact is constituted by the contact F of the byepass cable F<3>. Each external circuit E4 passes through a current-transformer case E<6> and is provided with a contact E which is constituted, as are also the contacts A<4>, by a bundle of spring-pressed plungers making butt contact with the arcuate contacts D of the rotary isolating switches. The fixed isolating contacts A<4>, E, F are arranged at 120‹ with respect to the axis of the insulating member D<1> carrying the isolating contacts D, and the latter subtend an angle of slightly more than 240‹ and can be rotated in either direction in 60‹ steps, thus providing six positions, in three of which all three contacts are interconnected, whereas in the other three, two are interconnected and isolated from the third. Thus, each circuit E<4> can be connected to either or both adjacent breakers, or can be isolated, leaving the ring complete. Horizontal shafts G<1>, H<1>, J<1>, K<1> carry earthing members G, H, J, K for earthing, on all three phases simultaneously, the cable E<4>, the two contacts A<4>, and the byepass cable F<3>, respectively. Three shafts G<1> . . . K<1> and the shaft D<1> pass into a chamber at the front of the gear, the outer walls L<1> of which chambers, together with intervening walls L<2>, forming a continuous wall bearing a mimic diagram of the circuits controlled by the'breakers, isolating, and earthing switches, with movable indicators representing the breakers and switches provided thereon, as described in Specification 457,128. The front chambers also contain actuating and interlocking mechanism for the switches, in addition to secondary switches for electrically controlling indicators on a similar mimic diagram at a remote point. The actuating shafts G<3>, H<3>, J<3>, Fig. 4, carrying the indicators G<2>, H<2>, J<2> are shaped to receive and be operated by a separate handle common to them all, and are directly connected by links and levers to the appropriate shafts G<1>, H<1>, J<1>, and to further shafts G<9>, H9, J<9> in the upper compartment L<3>, which further shafts carry secondary switches. The isolating switch is operated from a shaft D<3> through gearing D<4>, D<9>, D<10>, D<11> and a shaft D<12>, and further gearing D<5> ... D<7> operates the indicator D2, the shaft D<8> of which has a chain-drive connection D<17> with secondary switches in L3. The gearing may be of 18 : 1 ratio, so that three revolutions of D<3> cause a 60‹ rotation of the contacts D. The motor or solenoid A<7> operating the breaker is controlled by a handle A<6> or by a similar handle on the remote panel, the handles having locks A<8> operated by a common key so that only one can be unlocked at a time. Each handle can be moved to one side or the other of a central inoperative position for tripping and closing, respectively, the key being removable only in the central position. The indicator A<5> of the breaker is carried by a hollow tube surrounding the handle-shaft and connected to a spindle A<12> geared to the main operating shaft A<13>. Interlocking arrangements of generally similar character to those disclosed in Specification 457,128 are provided for the isolating and earthing switches, and an arrangement such as that described in Specification 457,127 may be used for closing the breakers. Specifications 410,207 and 425,107 also are referred to.