Patent GB-397149-A (GB)
Title: Improvements in or relating to electric switchgear
IPC: H02B11/167
Filed: 1932-02-18
Abstract: 397,149. Switchgear structures. REYROLLE & CO., Ltd., A., Hebburn-on- -Tyne, and ALLAN, A., Cragside, Ashleigh Grove, Tynemouth. Feb. 18, 1932, No. 4840. [Class 38 (v).] Oil switches; covers and lids; earthing.- A metal-clad circuit-breaker mounted so as to be withdrawable horizontally from an operative position beneath bus-bar or other chambers containing contacts is provided with substantially straight insulating bushings projecting upwardly from the cover of the tank, said bushings enclosing conductors connected at their lower ends with the circuit-breaker contacts and adapted, when the circuit-breaker is in the operative position, to contact at their upper ends with the fixed contacts in the bus-bar or other chambers, shutters operated by the movement of the circuit-breaker being provided for closing the openings in the chambers through which the bushings pass when the circuitbreaker is withdrawn from the switchgear. In one arrangement of threephase switchgear for connecting the bus-bars D<2> to feeder circuits E<3>, Fig. 1, the cover-plate A<2> of the circuit-breaker tank A carries three pairs of insulating bushings C, C<1>, the back bushings C being shorter than the front bushings C<1>. The bushings carry conductors connected to the fixed contacts B, B<1> of the circuitbreaker, the upper ends of the conductors being provided with contacts C<2>, C<3> adapted to engage conductors D<3> connected to the bus-bars D<2> or conductors E<2> connected through current transformers E<4> to the feeder connections E<3>. The fixed part of the switchgear is contained in a metal cubicle divided into compartments as shown, the compartment E<1> containing the conductors E<2> being at the front of the cubicle and above the level of the compartment D<1> containing the busbar conductors D<3>. The apertures in the compartments D<1>, E<1> through which the insulators C, Cl pass when the circuit-breaker is moved into operative position are closed, on withdrawal of the circuitbreaker, by cowl-shaped shutters G, G<1>, which are pivoted at G<2>, G<3> and connected together by a link G<4>. The shutters are moved automatically to close the openings by means of a roller G<5> on the shutter G, the roller engaging a slot A<3> in a lug A<4> on the cover plate of the tank A. A catch is provided to engage the roller G<5> and hold the shutters closed after complete withdrawal of the circuit-breaker, the catch being released on inward movement of the circuitbreaker. Latching means operated by a knob J<7> and interlocked with the circuit-breaker mechanism are provided to prevent movement of the circuit-breaker into or out of its operative position unless the circuit-breaker contacts are in the open position. A potential transformer Fl and fuses F<6> may be mounted in a chamber F at the top of the cubicle, the fuses being carried by the cover F<5> of the chamber in such a manner that they are isolated and earthed through an earthing terminal F<4> when the cover is raised. The cover plate A<2> of the circuit-breaker may be raised, for inspection purposes, after the withdrawal of the circuit-breaker from the cubicle, by means of a portable jack, Fig. 6, comprising a frame K carrying hooks K<1>, which engage flanges at the bottom of the tank, and a pivoted arm K<2> which can be bolted to a lug A<7> on the cover plate. A screw-threaded shaft K<3> with operating handle K<1> passes through a block K<5> on the upper end of the arm K<2> and engages a nut K<6> on the frame K to raise the arm K<2>. In Figs. 8 and 9 is shown an arrangement for a duplicate supply substation wherein incoming and outgoing feeders O, O<1> are connected together through a circuitbreaker L and are also connected through N, N<1> to two power transformers from which duplicate low-tension supplies are available. The circuitbreaker tank carries six bushings arranged in pairs L<3>, L<4>, L<5> decreasing in height from the front to the back, the openings through which the bushings are introduced into the cubicles being closed, on withdrawal of the cicruit-breakers, by means of a collapsible shutter Q arranged to fold up, like a bellows, at the back of the cubicle when the circuit breaker is in the operative position. The shutter is operated by means of a roller engaging a slot L<7> in a lug L<6> carried by the cover-plate of the tank, the several leaves of the shutter carrying rollers Q<2> engaging in channels Q<3> mounted in the cubicle on either side of the circuit-breaker. A potential transformer P, with a single set of bushings P<2> and a similarly operated shutter for closing the opening through which the bushings are introduced into the cubicle, may be provided. The feeders O, O<1> are connected to contacts N<2>, N<3> through isolating switches O<6>, O<7>, earthing switches O<8>, O<9> for the cables being also provided. In another arrangement, Fig. 11, eight circuitbreakers connected in mesh are employed, the circuit-breakers being arranged in two groups of four R, R<1> in two cubicles S, S<1> facing one another, so that the circuit-breakers are withdrawable into the space between the cubicles. Collapsable shutters V are provided for closing the openings in the bottom and front walls of the cubicle when the circuitbreakers are withdrawn.