GB812691A - Improvements in and relating to electric switchgear - Google Patents

Abstract

812,691. High-tension switches. ENGLISH ELECTRIC CO. Ltd. May 16, 1956 [May 20, 1955], No. 14601/55. Class 38 (5). A circuit-breaker with a powerdriven operating mechanism has a control member to initiate operation of the mechanism in either direction and which is thereafter moved by the mechanism during operation. An airblast breaker has a compressed air chamber 10 and fixed and moving contacts 21, 22 in insulators 13, 14. The moving contacts 22 are coupled by links 25 to cranks 26 secured to a rotatable shaft 27 having a further crank 29 coupled by a link 30 to a piston-rod 31 which carries a piston 32 slidable in a cylinder 33. To open the breaker, a valve 54 is operated to admit air under pressure to the left-hand side of a piston 52 which starts to rotate the air-pressure inlet tube 17 so that a link 47 moves the top of a lever 45 to the right. The lower end of the lever 45 is coupled by members 48, 49, 50, 51 to one of the cranks 26 and the lever 45 pivots about its lower end, thus moving a link 44 to cause anticlockwise rotation of a plate 43 operating a valve 39. This opens a passage 35 to the atmosphere, allowing the piston 32 to move upward and open the contacts until a plug 32a closes a passage 34a in a piston 34. Movement thus stops whilst the arcs are interrupted, and further movement takes place when sufficient air has leaked through an aperture 34b to allow the pistons 32, 34 to move upward together, with the link 44 now held stationary by the plate 43. Movement of the crank 26 results in the movement of the lower end of the lever 45 to the left, allowing the piston 52 to rotate the tube 17 as the link 47 is moved to the right. The plate 43 is reversely rotated to close the valve 39 at the end of the opening stroke. In a closing operation movement of piston 52 and tube 17 result in the operation of valve 40 so as to open the space below the piston 32 to the atmosphere and the operation takes place in one continuous movement. A limit switch assembly 57 may give a positive indication of contact-movement.