GB733782A - Improvements in or relating to liquid blast circuit breakers - Google Patents

Abstract

733,782. Liquid-blast circuit-breakers. ALLISCHALMERS MANUFACTURING CO. March 13, 1952 [March 15, 1951], No. 6524/52. Class 38 (5). A liquid-blast switch comprises an arcextinguishing device having a substantially straight passageway 34 with a passage 35 extending radially from the straight passageway, a fixed contact 24, a movable contact 27 and an auxiliary electrode 43 located intermediate the ends of the device and connected by a resistance 49 to the fixed contact 24. In Fig. 3, the arcextinguishing device has a pressure-resistant shell 28 enclosing a pressure-generating chamber 32 and a stack of plates of oil-absorbent material. the plates having punched-out portions and being so aligned as to form the passageway 34 surrounded by a plurality of relatively steep pitched coaxial helical passages 35. In the portion 20 of the stack above the electrode 43, the passages 35 are of relatively large crosssection, since the arc initially drawn between the contacts 24, 27 when the contacts are separated may be a heavy-current arc. This arc is shunted by the resistance 49 and is extinguished by the pressure generated in the chamber 32 forcing the oil or liquid to flow out of the helical passages 35 in helical jets directed into the portions of the passageway 34 cleared by the contact 27 as it moves downwards. The portion 20 of the stack may be vented through radial passageways 37, longitudinal passageways 36 and bores 38. When the contact 27 is withdrawn through the electrode 43, the arc between them is in series with the resistance 49 and is extinguished in the portion 21 of the stack, which is adapted to extinguish low current arcs, the helical passageways being of smaller cross-section and not provided with lateral vents. In a modification, Fig. 4 (not shown), the passages 36, 37 are omitted.