GB629991A - Improvements in or relating to liquid break electric circuit interrupters - Google Patents

Abstract

629,991. Oil-break switches. WESTING- HOUSE ELECTRIC INTERNATIONAL CO. Sept. 12, 1947, No. 25076. Convention date, Sept. 12 , 1946. [Class 38(v)] A liquid-break circuit - breaker comprises a relatively-fixed contact 15 co - operating with an intermediate contact 16 to produce a pressure-generating arc 18, and a movable contact 17 co-operating with contact 16 to produce an interrupting arc 20, the arcs being struck in chambers 19 and 21 formed by a plate structure 5 similar to that of Specification 571,091, and has valve means responsive to the pressure in the pressure - generating chamber 19 for controlling the flow of fluid into and/ or from the interrupting chamber 21. The contact 17 is followed by contact 16 upon downward movement of the former to draw the arc 18, the interrupting arc being drawn when a flange 50 on contact 16 strikes the shoulder 51 on plate 52. In Fig. 2, the exhaust passages 26 from the chamber 21 are controlled by valves 14, urged into the position shown by springs 43 which also hold a plate 36 carrying the contact 15. With high-current arcs, the pressure in the chamber 19 lifts plate 36, the effective surface of which is increased as cylinders 46 leave recesses 47, and opens valves 14 so that a blast of fluid flows through passages 22, 23 on to the arc 20 and exhausts through passages 26. With low-current arcs, however, the pressure is insufficient to open valves 14 and the blast is effected when the contact leaves its aperture in the plate structure 5, as shown in Fig. 2. A normally-open annular valve 39, in a recess 42 whose volume is equal to that of the contact 16 closes upon closure of contacts 15, 16 so as to prevent blocking of the upward movement of contact 16 due to the incompressible oil. In a modification (Fig. 5, not shown), the contact 17 is prevented from leaving the aperture in the plates, the contact 17 having at its lower end, a contact co-operating with a disconnect contact on the operating cross bar (Fig. 1, not shown). Instead of controlling the exhaust passages 26 by valves 14, the inlet passages 22 may be controlled by spring-urged valves 62, Fig. 7, whose operation is likewise dependent upon the pressure in chamber 19. The valve arrangements of Figs. 2 and 7 may be incorporated into one unit (Figs. 9 and 10, not shown).