GB504532A - Improvements in and relating to control arrangements for electric switches - Google Patents

Abstract

504,532. Slow-closing valves. BRITISH THOMSON-HOUSTON CO., Ltd. Aug. 26, 1938, No. 25140. Convention date, Aug. 30, 1937. [Class 135] An arrangement for controlling the actuation or the blowing or both of electric switches by a pressure gas in which the control impulse is prolonged a predetermined time comprises a control valve 1 which is opened to allow the passage of pressure gas by a control impulse applied for example manually or electrically and a piston 11 exposed to the pressure gas passed by the valve so as to complete the opening movement, the opening period of the valve being terminated by the subsequent equalization of pressure on the two sides of the piston. As shown in Fig. 1, the spring- pressed valve 1 controlling the passage of gas between a supply conduit 5 and a conduit 6 which passes gas to the switch for blowing or actuating purposes is operated by a lever 21 which is given an initial impulse by a push rod 25 or by an electromagnet 26. The piston 11 is coupled to the lever by a rod 22 and has a small bore 14 which restricts the passage of gas between its upper side and a chamber 30 on its under side. The piston cylinder 12 communicates with the valve outlet chamber by a conduit 10 which may be extended by a pipe 13 to a point near the valve. The bore 14 may be replaced by a passage in the cylinder 12 and may be adjustable. The valve stem 23 also carries an exhaust valve 27. In the modification, Fig. 3, the piston 11 and the valve 1 are arranged coaxially, the valve being opened initially by the impulse of the electromagnet 26 on the piston rod 23. The latter has a passage 34 which connects the upper piston chamber 37 with the valve outlet. The piston may be loose on-the piston rod and engage a collar thereon.