GB582599A - Improvements in electric circuit breakers - Google Patents

Abstract

582,599. Gas-blast switches. FNGLISH ELECTRIC CO., Ltd., and ROWLAND, F. G. July 7, 1944, No. 12987. [Class 38 (v)] A pneumatically-actuated gas-blast switch is mounted together with its series isolator, in the gas-reservoir 1a defined by a barrier 4 and end cap 5 for the metal tank 1, and carrying the switch isolator respectively. The fixed nozzle contact 7a of the switch, and an arcing-tip 7b are carried on an end member 7 forming with an insulator 8 and end member 6, the circuitbreaking chamber. Member 6 has a cylinder 6a within which is a piston 9a carrying the movable contact 9 and, if desired, a valve-member 9b closing the reservoir from the breaking-chamber. Member 6 is also formed with a fixed isolatorcontact 6c with a small blast-aperture 6e, and a small port 6d. When a control-valve 12 is opened the back of piston 9a is open to atmosphere via ports 6b and pipe 11, whereby the reservoirpressures on the front of piston 9a move the latter to open position against spring action 10, the end of the stroke being cushioned by closure of ports 9b by the piston. The arc formed is transferred to the tip 7b and is in shunt with a resistance 13 connected between members 6, 7. The movable isolator - contact 19 is pivoted at 20 and connected by insulating link 24 with a piston 23 in a cylinder 22, the ends of which are connected by pipes 25, 26 to valve 12 and by smaller pipes 22a, 22b to the reservoir. The pipes 25, 26 are chosen to ensure movement of piston 22 after the piston 9a, this movement being effected by exhausting the rear of the piston to atmosphere. When valve 12 is restored, air enters port 6d to equalize the pressures on the piston 9a, which is returned to closed position by spring 10. The pipe 22b also enables the pressures on piston 23 to be equalized, reclosure of the isolator being effected by exhausting the front of the piston. Valve 9b may be dispensed with, and the end of the silencer 14 may instead be closed by a valve opened simultaneously with valve 12, the break thus occurring in a pressure-atmosphere. The valve 18 may be opened by the air-pressure or by an electromagnet. Piston 23 may also operate, by means of shaft 35, auxiliary switches in a pocket 5a in the cap 5, access being had thereto by removing a cover 33. The blade 19 may have a snap-action spring, and may be replaced by a rotary or rectilinearly-moving member with a small bore therein to pass a blast of air, the contact being of the plug-and-socket, or knifeblade type. The movable isolator contact may be arranged on the end 6 of a second gas-blast switch mounted in plate 5 and oppositely-directed to the one in barrier 4. The arrangement of lead-in contacts 27, 30 is such that the two switches may readily be removed. The Provisional Specification states also that one or a pair of current transformers may be provided in the lead-in conductor or conductors, either within or outside the tank.