GB734372A - Improvements in or relating to gas-blast circuit breakers - Google Patents

Abstract

734,372. Fluid-pressure servomotor-control systems. ALLIS-CHALMERS MANUFACTURING CO. Feb. 26, 1953 [March 15, 1952], No. 5445/53. Class 135. [Also in Group XXXVII] The initial load on the fluid-operated contact-actuating mechanism of a gas-blast switch is reduced by providing an additional fluid motor with a relatively short stroke to crack open the blast valve, a second motor, such as a spring released by the main contact-actuating mechanism, then effecting substantially increased separation of the movable element of the valve from its seat. To open the switch, a solenoid 88 is energized to open a valve 25 so enabling gas to flow from a reservoir 6 through the valve 25 and a valve 29 to the cylinder 19 of the additional fluid motor. A piston 20 is then moved against the bias of a spring 22 to crack open the blast valve 104 and initiate the supply of blast gas to the switch contacts 7, 8. At the same time, the piston 20 through linkage 38, 39, 41 opens a valve 37 to admit gas to the " opening " fluid motor 45 and to the " closing " fluid motor 64. As the pistons 48, 66 of the fluid motors 45, 64 start to move, a valve 76 closes to shut off the supply to the motor 64, the initial starting impulse having been effected. The piston 48 through linkage 49, 50, 51 turns a shaft 31 to open the switch contacts. As the shaft 31 commences to turn, a cam 60 on the shaft releases a lever 61 which under the bias of a spring 62 fully opens the blast valve 104. Near the end of the opening stroke, the shaft 31 through linkage 51, 30 operates the valve 29 to dump the gas from cylinder 19 to atmosphere. The cam 60 then moves the lever 61 back to close the valve 104 and to re-stress the spring 62. To close the switch, a solenoid 105 is energized to open a valve 63 to admit gas to the motor 64 above the piston 66 which moves downwardly to turn the shaft 31 and close the contacts. During this closing motion, the cam 60 frees the lever 61, but the lever 61 is unable to move as the spring 62 is not strong enough to open the valve 104 against the gas pressure.