GB541165A - Improvements in control arrangements for gas blast circuit breakers - Google Patents

Abstract

541,165. Gas-blast switches. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 23, 1940, No. 18046. Convention date, Dec, 22, 1939. [Class 38 (v)] A pneumatically-actuated gas-blast switch has a plurality of pistons for operating the movable contact, fluid under pressure being supplied to one side of each piston for actuating the contact to open position, to the opposite side of one piston during the contact-opening movement so as to retard the opening movement and to the opposite side of another of the pistons for actuating the contact to closed circuit position. Fig. 2 shows the invention applied to the switch of Specification 544,017, in which the blast-conduits 16 of the phases are supplied from a tank 17 through a manifold 20, and the movable contacts (not shown) are slid by means of arms 22 secured to flanges 23 on a common shaft 21. Further flanges 31, 32 on shaft 21 are connected through rods 29, 30 with pistons 27, 28 in cylinders 35, 36. A pipe 37 leads from tank 17 to a cylinder 39 in which is a double piston 40 operated manually or by solenoid, and centred by springs 41. Pipes 42, 43 lead from one end of the cylinder 39 to the "opening" side of the pistons 27, 28, whereas a pipe 44 leads from the other end of the cylinder to the "closing" face of piston 28. The cylinderends also have vents to atmosphere 45, 46. For retarding the opening movement, a pipe 47 leading from the manifold 20, conducts gas at a considerably-reduced pressure as compared with the operating pressure, to the "closing" face of piston 27, the connection including an elbow 48 in which is a check valve normally biassed closed by a spring and having a number of small openings to provide for slow escape of the gas as the opening movement terminates, Fig. 4 (not shown). The flanges 31 are adapted to open the blast valve through a rod 52 and mechanism 34 as described in Specification 544,017 the arrangement being that a blast is supplied during opening and closing of the switch, and through independent parts of the mechanism 34, (Fig. 3 (not shown). The closing movement may be cushioned without impairing the speed of opening, by means of check valves in pipes 42, 43 similar to that in elbow 48. The Specification refers also to opening of the valve 38 in response to abnormal circuit conditions and to repeated closures within short intervals.