GB872337A - Improvements relating to electric isolating switches - Google Patents

Abstract

872,337. Air-break switches. SWITCHGEAR & EQUIPMENT Ltd., and OXLEY, D. A. J. March 2, 1960 [March 4, 1959], No. 7597/59. Class 38 (5). In an isolating switch having vertical insulators 10 carrying fixed contacts 12 arranged to be bridged by a moving contact bar 14 carried on an intermediate movable insulator 11, the latter is rotated to bring the moving contacts 13 into the fixed contacts 12 and then moved axially to wedge the moving contacts into the fixed contacts. The bar 14 is carried on arms 15 pivoted at 16 to offset projections of a bracket 17 secured to the insulator 11 and arranged so that the axis of the bar 14 intersects that of the insulator 11. In the open position the bar 14 rests on adjustable stops 18. The insulator 11 is carried on a sleeve 21 slidable in a cylindrical guide 22 which is slotted at 25 to receive rollers 26 on pins projecting from the sleeve 21. A nut 23 forming part of the sleeve 21 engages a motor-driven screw-threaded shaft 24 which is rotated to raise and lower the insulator 11. As the sleeve 21 is lowered to close the isolator the rollers 26 enter the inclined portions 28 of the slots 25 and the parts 21, 11, 14 are rotated until the contacts 13 enter the fixed contacts 12 and the .rollers enter the vertical parts 27 of the slots 25. On further downward movement of the insulator 11 the arms 15 rotate about their pivots 16 to twist the bar 14 so that projections 32 on the contacts 13 wedge in the fixed contacts. The latter are formed of bent spring blades 33 having outer links secured by bolts 41 and reentrant portions 34 connected by a case 35 attached to the lower limb, a bolt 36 being secured to the upper limb with a compression spring 37 between a flange 38 on the case and the head of the bolt 36. The case limits the inward movement of the blade ends and a nut 39 may be adjusted to set the spring tension. The curved parts of the slots 25 are arranged to give uniform acceleration and deceleration to the bar 14 and the shaft 24 may be coupled to a polyphase drive shaft by skew-gears 44, 45. The sleeve 21 may alternatively be formed as a piston for hydraulic operation.