GB578780A - Improvements in or relating to fluid blast electric circuit interrupters - Google Patents

Abstract

578,780. Fluid-blast switches. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Feb. 9, 1944, No. 2392. Convention date, Feb. 10, 1943. [Class 38 (v)] In a switch in which the fluid-pressure set up by a pressure-generating arc produces a blast to extinguish another arc in series, excessive pressure is prevented by causing the pressure to act upon the movable contact of the pressuregenerating arc so as to keep the latter short. The Figs. shows one unit of a pair which are secured to lead-in insulators of conventional oil-switches having main movable contacts 11 connected by a cross-bar 9, Fig. 1 (not shown). The movable pressure-arc contact 13 is pivoted at 14 and an intermediate contact 19 has a limited follow-up on contact 11. The arc-quenching structure shown is similar to that of Specification 571,091 and comprises inlet passages 25 leading to the main arc, and exhaust passages 26 at rightangles to the inlet passages 25. A link 30 pivoted to contact 13 at 29, has pin-and-slot connection at 31 with an operating- rod 36 bearing on the cross-bar 9. A spring 35 is compressed between a flange 37 on the rod 36 and a washer 34 slidable on the rod and bearing on the pin 31. A piston 38 having apertures therein adapted to be closed by the flange 37, is slidable on a reduced part of the rod 36 between stops in the enclosure. When the cross-bar is lowered, a spring 44 lowers the rod 36 and, when the top of the slot engages pin 31, contact 13 separates from 19 substantially simultaneously with contact 11. If the pressure set up by the arc at 13, 19 is excessive, the force on piston 38 overcomes the spring 44 to halt and even reverse the movement of contact 13 so as to keep the pressure-arc short and so reduce the pressure. In exceptional cases, the piston 38 will move right back and the ports therein be opened to provide a safety-valve. With normal pressures, however, the piston 38 produces a reinforcing oil-blast on the main arc. A gas-escape valve 16 is adapted to be closed by the pressure in the structure. In Fig. 8, the contact-pressure for contact 13 is provided by a spring 62 which allows it to follow contact 63 until arrested by engagement of piston 55 with spring-stud 71, after which the contact 63 continues to follow contact 11. On excessive pressure the piston 55 is further raised and ultimately exposes relief-ports 54.