GB526849A - Improvements in or relating to electric circuit interrupters with arc extinguishing means - Google Patents

Abstract

526,849. Air-break switches. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. March 27, 1939, No. 9511. Convention date, March 25, 1938. [Class 38 (v)] In an electric switch, having a movable switch blade associated with a stationary contact, there is an arc extinguishing device comprising relatively movable arcing contacts, one of which is electrically connected to the stationary contact. The arc extinguishing device is operated by a rotatable member which co-operates with means on the movable switch blade so as to (1) connect the blade in circuit with the arcing contacts and (2) open the arcing contacts on disengagement of the blade from the stationary contact. On closing the switch the cycle occurs in the reverse order. In Fig. 3 a movable switch blade 23, supported on insulator 15 and operated by rotatable insulator 17 by means of crank, connecting rod and links 33, 43 and 35 co-operates with stationary contact 21 and the extinguishing device 51 supported on insulator 13. In the closed position the cam plate 129 forms an alternative path through the arm 127, flexible lead 125, and extinguishing device 51 to the terminal plate 19. On opening the switch the circuit is maintained through the cam plate and the extinguishing device until the movement of arm 109 following the contour of the cam plate breaks the circuit inside the extinguishing device. Further movement of blade 23 to the vertical position isolates the circuit. In Fig. 6 the extinguishing device consists of alternate fixed and movable discs 61, 85, consisting of insulating material which may evolve an arc extinguishing gas on being exposed to the action of an arc. Each disc carries contacts 67 or 91 (see Fig. 8) which form a circuit through the device capable of being broken by the rotation of the movable discs by means of the axle 83 connected to the arm 109. The device consists of two parts, in one of which the separation of the discs is greater than in the other and so constructed with lost motion connection 119 that the circuit is broken first in that part containing the greater separation between the discs. The whole is enclosed in casing 57 with closure caps 55 supporting terminals 99, 105, and a vitreous outer casing 53 and the discs are spaced by means of rings 63, 87. Fig. 9 shows an alternative arrangement in which the arm and cam plate is replaced by crank 137 with a V-shaped indent 141 which is operated by pin 139 on the movable blade.