GB1201100A - Improvements in or relating to electric switches - Google Patents

Abstract

1,201,100. Air-break switches; switchboards. BRITISH INSULATED CALLENDER'S CABLES Ltd. 27 Feb., 1969 [28 Feb., 1968], No. 9670/68. Heading H1N. An electric switch comprises a fixed cylindrical contact 12, a cluster of resilient contacts 18 adapted to bear upon the peripheral contact surface of fixed contact 12, and an annulus 26 of insulating material movable in an axial direction to separate the fixed and resilient contacts. Sixteen resilient contacts 18 are pivoted on tubular metal stem 9 being supported from ring 25 by bow-springs 24, stem 9 being welded to bus-bar 3 in a bus-bar panel 1 comprising bus-bars 2, 3, 4, sandwiched between and bonded to layers 5 of solid insulant secured to the wall 6 of a transformer tank. Contacts 18 may alternatively be supported by a garter spring or springs. Fixed contact 12 is carried on a metal rod 14 passing through bus-bar panel 1 and wall 6 and insulated fiom metal stem 9 by insulating sleeve 16. Insulating sleeve 16 is bonded to rod 14, stem 9 and panel 1 to provide an oil-seal for the transformer tank, sealing washer 7 is also provided for this purpose. Around rod 14 is a current transformer 44 associated with an indicating instrument 43 visible through window 42 in the housing which also has ventilation openings 46. Insulating annulus 26 is coupled to or integral with a rod 28 slidable in bearing 32 of the moulded plastics housing and detachably secured to rod 28 is a handle 34, Fig. 2 (not shown) which is movable axially in a slot in the housing, being pushed forward to slide annulus 26 between the contacts to open the switch. The position of handle 34 provides a visual indication of whether the switch is open or closed. The end of handle 34 is provided with a hole which can be aligned with holes in a bracket 37, Figs. 2, 3 (not shown) in either of the handle's two positions for a padlock. Handle 34 is secured to rod 28 by means of a blind threaded hole 29 or by a bayonet fitting. Resilient washers 30, 33 cushion the movement of annulus 26. Two or more switches may be mounted on bus-bar panel 1. A switch 45, Fig. 2, may be mounted adjacent the instrument 43 for selecting the required ratio between the transformer secondary terminals.