GB1091302A - Gas-blast circuit breaker - Google Patents

Abstract

1,091,302. Gas blast switches. WESTING- HOUSE ELECTRIC CORPORATION. Dec. 14, 1965 [Dec. 21, 1964], No. 53010/65. Heading H2B. In a puffer-type gas blast circuit breaker the blast gas is compressed during opening of the contacts between two members 23, 24 one of which moves in the same direction as the movable contact assembly 25 while the other moves in the opposite direction. A main piston 23 is attached to the movable contact 25 and to an operating rod 27 rigid with an isolator contact 19. The secondary piston 24 is slidable along the rod 27 and both pistons move within a fixed cylinder 17 the main piston 23 being biased downwards by a heavy spring 21 while the secondary piston 24 is biased upwards by a lighter spring 28. Piston 24 is normally held down by latches 42. Two of the assemblies shown are mounted in a tank filled with SF 6 , air, &c. (Fig. 1, not shown), their two isolator contacts 19 being bridged by a movable isolating contact (13). In the closed position the contact (13) acts to hold piston 23 and contact assembly 25 in the position shown against spring 21. To open the breaker contact (13) is moved downwards; spring 21 drives contact 19 downwards causing hooks 49 thereon to withdraw latches 49 and allowing piston 24 to move upwards. Hooks 49 free themselves from the latch mechanism and piston 23 continues downwards. Rising pressure between the pistons 23, 24 eventually exceeds the force of spring 28 and piston 24 changes direction and is driven back downwards into the latched position. The pistons are damped by rising pressure beneath piston 24. The contacts are reclosed by raising contact (13) and rod 27 again, valves 51, 55 permitting gas to flow in rapidly. In a modification (Fig. 5, not shown) the fixed contact 22 of the breaker is hollow and the blast gas flows through it; an arcing electrode 34 (Fig. 4, not shown) may also be hollow. In a further modification (Fig. 7, not shown) the valves 51, 55 are omitted and the damping action does not occur. In an alternative arrangement (Fig. 6, not shown) the cylinder (17<SP>1</SP>) is movable with the movable contact 25 while piston 24 is moved in the opposite direction by springs. The cylinder is moved by a crank 83 which may be operated pneumatically and is latched in the contact's closed position. Current transformers (76-78) may surround the tank (71).