GB490518A - Improvements in electrical switchgear - Google Patents

Abstract

490,518. Gas-blast switches ; pneumatic actuation of switches. BRITISH THOMSON-HOUSTON CO., Ltd., and TRENCHAM, H. Dec. 14, 1936, No. 34301. [Class 38 (v)] In a circuit-breaker or isolating switch in which the casing containing the switch is filled with pressure gas, and mechanism for its operation includes a piston and cylinder or like device enclosed in, or communicating with, the casing and having its pressure side in communication with the casing-interior, the exhaust side of the piston communicates through an operating valve with atmospheric pressure so that the casing-pressure is utilized to open and close the contacts. The movable contact 2 is guided at 7 for horizontal movement by means of a piston 10 in a cylinder 11 on one wall of the pressure-gas filled container 3. The front of the piston 10 communicates over a narrow annular orifice 22 around the piston-rod 12 with the casing-interior, and over a pipe 24 and valve 25 with the atmosphere. A narrow inlet 21 to the casing 3 is provided at the back of the piston 10, and a conduit 17 leads thence to a chamber 16 which can be opened by valve 17a to communicate over ports 19 and passage 20 to atmosphere. To open the switch, solenoid 18 is energized to open valve 17e, so putting chamber 16 and, over conduit 17, the back of piston 10 to atmosphere. The casing-pressure acts through orifice 22 to move piston 10 to the left, and also sends a blast of gas through passages 13 between baffles 14 and through pipe 15 to chamber 16, so blowing out the arc. The switch is reclosed by energizing solenoid 26 to open valve 25, whereupon gas-pressure acts through orifice 21 and pipe 17 to move the piston 10 to the right. The orifices 21, 22 are of such size that they do not affect the opening and closing operation, respectively. Piston rod 12 may be extended beyond the casing wall to operate limit-switches for de-energizing the solenoids 18, 26 at the end of the opening and closing movement, respectively. The lead-in bushings 4, 9 have enclosures 27 communicating with the casing over holes 28 to provide additional gas-reservoirs. The cylinder 11 and chamber 16 may be located outside the casing, in which case orifice 21 would lead to the latter over a conduit similar to 17 and the latter would be externally arranged. Switches of existing design may be connected over bushing-insulators to pressure-air filled switchgear, such as bus-bar chambers serving as reservoirs. Specification 123,812, [Class 38 (v)], is referred to.