Patent GB-556215-A (GB)
Title: Improvements in withdrawable electric switchgear structures
IPC: H02B11/133
Filed: 1942-02-18
Abstract: 556,215. Switchgear structures. FOSTER TRANSFORMERS & SWITCHGEAR, Ltd., and LOWE, R. G. Feb. 18, 1942, No. 2129. [Class 38 (v)] A withdrawable switchgear structure comprises a circuit-breaker 18 which is mounted on trunnion-like arms 24 having pivot rollers 25, 28 engageable with slots 27, 29, respectively, in the side part of the structure. The slot 29 terminates in a gate 30 having separate slots corresponding to duplicate-busbar and earthing contacts 13, 14, 17, respectively, corresponding cable contacts 16 being provided. Pivot 28 also engages in a slot 36 formed in a plate 31, the axle 32 of which engages in a slot 33 and can be preset by handle 34 into any of three positions corresponding to the slots in gate 30. Starting from the " ground " position shown, the capstan handles 39 are operated to rotate plate 31 and, by means of parts 36a of slot 36, move roller 28 round slot 29 until it is beneath the selected gate slot and lies, due to curvature of slot 29, over the part 36b of slot 36. Meanwhile the pivot 25 has been moved to the foot of part 27a of slot 27 and further movement of plate 31 causes a ramp 37 thereon to engage roller 25 and raise it in slot part 27a thus moving the breaker 18 into the selected operative position. A counterpoise 40 for taking the weight of the tank may be provided. In a modification, Fig. 2 (not shown), the final breaker movement into operative position is a horizontal one, rollers 25, 28 being moved along their slots by a pivoted hand lever, and an additional hand lever selecting the position before the first-named hand lever completes the movement into the selected gate-slot. In a simple, vertically-withdrawable example, Fig. 3, roller 28 takes in a slot 60 in a plate 56 balanced about its pivot 57 in slot 54. The plate is operated by a link 61 having a roller 63 which takes in a fixed slot 29 and in a slot 64 in a cam plate 65 which is pivoted at 66 and operated by handle lever 67. In the " ground position shown, the levers 67 occupy position 67B, the slot position is 64B, plate 56 in 56B, slot 60 in 60B, and link 61 in 61B. To raise the tank to position 24C, 67 is lowered to 67C and slot 64 to 64C, whereby link 61 rotates plate 56 into a position in which slot 60 is at 60C, thereby, through rollers 28, raising the arms 24 and moving rollers 25 along the slots 27. Lever 27 is then raised slightly and lowered, so as to carry links 61 over the dead-centre, and then raised to 67B in which position slot 64 is again at 64B. Arm pivots 23 then enter slots 55b and a notch 58 on plate 56 engages a stop 59, so that further movement of 67 causes plate 56 to pivot about 59 as allowed by slot 54, raises slot 60 from position 60D and causes the tank to be raised up slot 55a into the operative position. The counterpoise is in the form of a spring plunger 68 anchored between the frame and the axle of rollers 25 and arranged to exert no force in the raised position of the tank and substantially constant force for any position of roller 25 in slot 27b. The breaker 18 may be oil, or gasfilled.