GB548520A - Improvements in and relating to fluid operating mechanism for electric circuit breakers - Google Patents

Abstract

548,520. Fluid-pressure servomotor control systems. BRTITSH THOMSON-HOUSTON CO., Ltd. Sept. 10, 1941, No. 11606. Convention date, Sept. 12, 1940. [Class 135] [Also in Group XXXVII] A pneumatically-actuated circuit-breaker, preferably of the gas-blast type for example, as described in Specification 544,017, [Group XXXVII], is adapted for trip-free opening and high speed reclosing by the provision of a dumping valve or valves between the source and the operating motor, the valve or valves being operated by the back-pressure set up on reversal of the motor to exhaust the back-pressure to atmosphere. The movable contact 17 is connected to the operating piston 23 by a rod, the two parts 24<SP>1</SP>, 24<SP>11</SP> of which are inter-connected by a lostmotion device 25. When the piston 23 is raised in response to opening-fluid pressure, a projection 30 engages a lever 26 which trips a latch 27 normally retaining the contact 17 in closed position. An opening spring 28 and balancing spring 281 charged by the closing movement of piston 23 thereupon expand to aid the fluid-means to open the switch. The fluid is admitted to the cylinder ends through opening and closing valves 33, 34 operated by electromagnets 37, 41 against the action of springs 35, 39 acting on levers 36, 401. Lever 401 comprises two co-pivoted parts, 40a, 40b normally latched together at 43 so as to move as one lever. The latch 43 is trippable by a rod 45 when solenoid 37 is energized by closure on to a fanet, thus enabling spring 39 to close valve 34 and open a port 42 to exhaust the pipe 50. In this way a valve 47, which is held on its seating by a light spring 48 and by the incoming-fluid pressure, is pushed back by the back pressure set up in the large space 46 by the reversal of piston 23 so as to enable the pressure to exhaust through ports 51. A similar valve 53 and ports 57 are provided in order to enable high-speed reclosure of the switch. The Specification as open to inspection under Sect. 91 refers also to Specification 1536/41.' This subject-matter does not appear in the Specification as accepted.