GB627485A - Improvements in and relating to fluid operated electric circuit breakers - Google Patents

Abstract

627,485. Fluid - blast circuit - breakers. BRITISH THOMSON-HOUSTON CO., Ltd. (Timmerman, J. W.). Nov. 2, 1945, No. 29152. [A Specification was laid open to inspection under Sect. 91 of the Acts, May 8, 1946] [Class 38(v)] The movable contact 13 of a fluid-blast, fluid-operated circuit-breaker is operated by two pistons 30, 31, working in cylinders 33, 34, and interconnected by a rack 32 engaging a pinion 35 on a shaft 36, to which the contact 13 is connected by a link 59 and arm 57, the initial opening movement of the contact beiing effected by an auxiliary piston 44 working in a cylinder 45. Upon operation of valve 48, air is supplied to cylinders 45, 40, and pistons 44, 30, 31 move to the right, thereby rotating the shaft 36 clockwise with toggle 57, 59<SP>11</SP> overset. Simultaneously, a cam (not shown) on shaft 36 opens a blast valve in conduit 26 to cause a blast of fluid across the contacts. This blast helps the upward movement of the contact 13, but towards the end of the stroke of the piston 44, the air in the cylinder 40 opposes the motion of a piston 37 and thereby keeps the speed of the contact substantially constant. As the contact 13 is withdrawn from the arc chute 2, the blast of fluid is cut off, so that the force on the contact is reduced. To compensate for this, a bye-pass 52 in the cylinder 40 is opened to relieve the pressure on the face of piston 37, and at the same time a bye-pass 50 is uncovered to allow the full fluid pressure in cylinder 45 to act directly on piston 30. A final dash-pot action occurs when the piston 37 passes the second part of the bye-pass 52. The circuit-breaker is closed by passing air into cylinder 34, to force pistons 30, 31, 44 to the left, dump ports 56 permitting rapid reversal of the pistons in the event of trip-free operation of the circuit-breaker. Specification 544,017 is referred to.