GB759729A - Improvements relating to high-voltage electric switchgear - Google Patents

Abstract

759,729. Switchgear structures. REYROLLE & CO., Ltd., A. Nov. 12, 1954 [Aug. 13, 1953], No. 32840/54. Divided out of 759,708. Class 38(5) H i g h-voltage switchgear housed in a building includes a supply terminal 41 and a load terminal 42 housed in separate compartments and interconnected by an isolater which comprises an insulating bushing 43 surrounding a bridging conductor, the bushing being movable between an operative position in which the conductor extends between the compartments and interconnects the terminals 41, 42, and one or more isolating positions in which the bridging conductor does not extend between the compartments, the bushing also carrying an earthing conductor 50 arranged to connect one of the terminals to earth when in the isolating position. The bushing is supported by an earthed metal flange 46 which may be pivoted at 47 to a fixed support. There may be two isolating portions, one with the terminal 42 earthed (Fig. 4) and the other with the terminal 41 earthed. In either of these two positions the aperture in the wall 48 through which the bushing 43 extends in the operative position is automatically closed by a door 51. In another embodiment (Fig. 7) the bushing is pivoted about a transverse axis 55 passing through its mid-point and is provided with two earthing conductors 56, 57. In the isolating position both terminals 41 and 42 are earthed and the bushing itself forms part of or constitutes the locking-off door. The load terminal may comprise the upper terminal of a circuit breaker, the isolating bushing being used for bus selection and isolation as described in Specification 759,708. Alternatively the isolater may be positioned on the other side of the circuit breaker to connect it to or isolate it from a line.