GB821069A - Improvements in and relating to air or gas blast electric circuit-breakers - Google Patents

Abstract

821,069. Gas-blast switches; pneumatic actuation of switches. BRITISH THOMSONHOUSTON CO. Ltd. Jan. 17, 1958 [Oct. 25, 1956], No. 32581/56. Class 38 (5). In a gas-blast circuit-breaker in which a moving contact 9 is separated from a co-operating contact 17 by a gas pressure applied to the arc chamber 1, the contact 17 is arranged to follow the contact 9 during the initial part of the latter's opening movement and is then arrested so that the contacts separate. In the form shown, the contact 9 is mounted on a rod 8 attached to shouldered piston 7 slidable within stepped cylinders 5, 6. The piston is urged to the left by a spring 11. The nozzle contact 17 is formed at the end of a tube 18 having parts 21 and 22 slidable within stepped cylinders 19, 20. The tube 18 is also urged to the left by a spring 23. Pressure gas applied to the arc chamber 1 from an inlet passage 4 passes through ports 25 and acts on the part 22 to move the tube 18 and also the contact 9 and its attached piston to the right. This movement uncovers ports 16 in the cylinder 6 so that the pressure gas is applied to the piston 7 moving it to the right. The following movement of the tube 18 is then arrested by the part 22 abutting the step 19a between the cylinders 19, 20 and the contacts separate, the gas blast passing down the tube 18 and through the ports 32a to the exhaust passage 31. Finally, gas leaks around the piston 22 and the tube 18 is returned to its original position by the spring 23, thus closing the exhaust passage 31. The contacts are therefore kept open by the gas pressure in the arc chamber 1. Release of this pressure allows the contacts to return to their original closed position.