GB455291A - Improvements in or relating to liquid-insulated metal-clad electric switchgear - Google Patents

Abstract

455,291. Switchgear structures. REYROLLE & CO., Ltd., A., Hebburn-on-Tyne, ALLAN, A., Cragside, Ashleigh Grove, Tynemouth, and MIRREY, J., Cairnsmore, Osbaldeston Gardens, Gosforth, Newcastle-on-Tyne. April 16, 1935, No. 11723. [Class 38 (v)] In metal-clad switchgear of the kind in which an insulated bus-bar or bus-bar section is mounted in a liquid filled conduit L extending between liquid - filled end chambers A, B containing contacts A<1>, B<1> with which the busbar co-operates, the busbar mounting comprises end fittings for attachment to the end chambers, flexible liquid-tight connections between the conduit L and the end fittings, and a ball-joint between the bus-bar insulation and one end fitting, the other end of the bus-bar section being free to slide in a support which is carried by the end chamber at that end and is so arranged as to permit of slight angular movement of the bus-bar section therein. In the arrangement shown, the insulated bus-bar section comprises flexible leads C mounted in a hollow insulator in the form of a rigid metal tube D constituting the innermost layer of a condenser insulator D<1>. The leads C connect butt contacts E mounted at each end of the tube D, the contacts being pressed outwardly by helical springs E <1> whose inner ends abut against a partition D<2> in the insulator. In order to prevent the passage of oil through the insulator from one end chamber to the other, a block F threaded on the leads C carries on its periphery a rubber ring F<1> which is pressed into engagement with the inner surface of the tube D by a gland F<2>. On the outside of the insulator D<1> near the chamber A is mounted a metal sheath G having a spherical outer surface which engages internal spherical surfaces in a pair of annular blocks H, H<1> which are pressed towards each other to secure tight engagement with the sheath G by bolts H<2>. The block H is bolted to an annular plate K connected by a short tube K<1> to a flange K<2> which is bolted to the wall of the chamber A around the orifice therein. Packing rings are provided to prevent the passage of oil through the ball joint and the various bolted surfaces. The metal conduit L is spaced away from the insulation at the end near the chamber A by projections on the metal sheath G, and is connected to a metal tube L<2> surrounding the ball joint by means of a flexible-metal diaphragm L<1>. A flange L<3> on the tube L<2> is bolted to the annular plate K. At the end near the chamber B, the conduit L is attached to a flexible metal bellows M which extends back around the conduit to a ring M<1> bolted to an annular plate N which is connected by a cylinder N to a flange N<2> bolted to the wall of the second chamber B. The bus-bar insulation at this end carries a metal sheath O which can slide between the parts P, P of a divided supporting plate bolted over the orifice in the end chamber wall, the inner edges of the supporting plate being rounded to permit slight angular movement of the sheath O. The bus-bar mounting is thus self-aligning, notwithstanding any want of exact parallelism between the end walls of the chambers or any slight differences of level between the orifices; the mounting also permits of relative longitudinal movement of the various parts to allow for temperature expansion and contraction. The section can readily be dismounted by detaching the ring M<1> from the plate N and by detaching the flanges K<2>, N<2> from the end walls of the chambers A, B. The whole fitting at the end near the chamber B can now be withdrawn along the bus-bar to permit of the detachment of the divided plate P, P<1>, whereupon the whole mounting can be moved towards the chamber B to bring the other end of the bus-bar clear of the chamber A. In a modification, Fig. 5 (not shown), the flexible leads are replaced by solid rods of small cross-section arranged to make plug-and-socket connections with contact-members in the end chambers, the rods being sufficiently flexible to permit of self-alignment. Specification 425,107 is referred to.