Patent GB-642176-A (GB)
Title: High tension compressed gas switch
IPC: H01H33/867
Filed: 1947-12-29
Abstract: 642,176. Gas-blast circuit-breakers; protective cut-out arrangements. ETABLISSEMENTS MERLIN & GERIN. Dec. 29, 1947, No. 34402. Convention date, April 6, 1940. [Class 38(v)] The exhaust valve or valves of a gas-blast circuit-breaker comprising one or more movable contacts are arranged to be closed by the blast gas against spring bias shortly after the extinction of the arc, so maintaining the pressure in the contact chamber. Compressed gas is supplied to insulators 30 and passes through orifices 17 to move pistons 14 against the action of springs 16, the rear faces of the pistons being open to the atmosphere through distributers 19, thereby separating tubular contacts 2. After a small movement thereof, orifices 24 are closed so that the blast gas escapes through openings 5, 21 into the exhaust chambers, each of which contains a metal cooling grid, such as 25. The exhaust valves 6, 22, are thereby urged to close but their inertia is so arranged that the arc is extinguished before they do so. An isolator 13, Fig. 5, may then be opened and the insulators 30 connected to atmosphere by means not shown, in order to close the contacts. Alternatively, the distributers 19 may be moved by a cam 39 on a rod 40 operated by a piston 43, so as to supply compressed gas to the rear of the pistons 14, so that springs 16 reclose the contacts. In this case, a further slight blowing will occur when the orifices 24 are uncovered, so as to relieve the pressure on valves 6, 22 which re-open. The distributers 19 may, alternatively, be manually, mechanically or electrically operated. In Fig. 1 (not shown), a single movable contact co-operates with a fixed nozzle contact in a generally verticallyaranged structure. In a modification (Fig. 4, not shown), the hood 27 of the exhaust chamber is spring-loaded and lifted by the exhaust gases. In Fig. 5, a cock 57 is closed or open, respectively, according as to whether the isolator 13 is to open or remain closed. In the former case, on overload in the line 48, a relay 50 is energized over a current-transformer 49 to close contacts 81, 82, thereby energizing the electro-magnetic valve 53 which opens and causes a main valve 52 to open. Compressed gas is thus supplied to the circuit-breaker 47 whose contacts open and exhaust valves eventually close. When the arc is extinguished, coil 50 is de-energized, but valve 53 is held open by the energization of its coil over maintaining contact 80 and normally-closed contact 71. After a time-delay determined by an adjustable retarding device 60, a piston 58 moves to the right to supply gas through pipes 54, 76 to cause opening of isolator 13 by piston 74. At the same time contacts 77 are opened and valve 53 closes to stop the gas supply and exhaust the circuit-breaker to atmosphere at 52. The circuit-breaker contacts therefore reclose, leaving the isolator open, the latter being closed when desired by pressure applied to the left-hand side of piston 74 by means not shown. If the isolator is to remain closed on overload, the circuitbreaker contacts are opened as before, but a piston 59 is operated before piston 58 by gas supplied through a timing device 61 which acts more quickly than the device 60. Gas therefore passes through pipes 65, 63 and causes piston valve 62 to vent the left-hand side of piston 58 to atmosphere so preventing operation of the isolator. At the same time, gas through pipe 66 moves the piston 43 to the right, thereby operating distributers 19 and causing the circuitbreaker contacts to close. If the fault has been cleared, contact 71 is opened by a fluid-pressure capsule 70 after a time determined by a retarding device 72, thereby closing valves 53, 52. If the fault persists, however, a valve 64 is opened by its coil which is energized over contact 69 which has been closed by pressure in pipe 66. The pipes 63, 66 are thereby vented to atmosphere and piston 43 moves to the left, so that the circuit-breaker contacts are allowed to re-open. The left-hand side of piston 58 is also exposed to pressure and the isolator is opened. Contacts 77 are opened so that valves 53, 64 are de-energized and close, returning the system to its original state.