GB556063A - Improvements in or relating to electric circuit breakers adapted for automatic reclosure - Google Patents

Abstract

556,063. Automatic circuit-breakers. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Aug. 7, 1942, No. 11096. Convention date, Sept. 15, 1941. [Class 38 (v)] A circuit-breaker adapted to be normally closed and automatically reclosed by power means at least by the time it reaches full-open position, has automatically-selective means for causing a greater closing force to be applied to the breaker on an automatic reclosing operation than during at least an intial part of a normal closing operation. The breaker comprises. Fig. 3, contacts 11 adapted to be closed, against spring- action 15, by a pivoted lever 19 connected to a rod 25 actuated by the piston 103 of a pneumatic motor 29, the rod being also connected to a lever 35 co-operating with a retaining latch system trippable by an overload coil 85 or under control of a push button 303. In Fig. 1, lever 35 carries a roller 47 engageable with a latch lever 51 which is pivoted at 53 and biased by an adjustable spring (plunger 57. This latch is ineffective alone, and accordingly is itself engaged by a latch 67 pivoted at 69 and operated to release position, against spring- action 75, by the core 79 of coil 85. This lever is held in tripped position by a further lever 95 normally held down by lever 35 but movable under spring-action 97, when the breaker opens. so that a part 99 thereon engages latch 67 until the breaker is in reclosed position. Reclosure is effected by admitting air above piston 103 by means of a main valve 127 operated by piston 147 under control of a pilot valve 117 actuatable by electromagnet 165 and armature 167 or by hand-button 175. If the breaker is closed on an overload, the coil 85, in addition to tripping, opens an exhaust pilot valve 203 to connect cylinder 29 by way of conduits 207, 213, Fig. 2, with the top of a main valve 187 which opens and connects the cylinder ports 181, Fig 1, direct to atmosphere, so dumping the closing fluid and permitting rapid opening. The positions of the piston 103 for normal and automatic reclosure are shown at C, R, respectively, Fig. 1. The cylinder 29 communicates through ducts 345, 347 with opposite sides, respectively, of the operating piston 335 of a valve 325 in the supply pipe. When automatically reclosing from position R, the valve 325 is held in the position shown because the air has access to both sides of the piston 335, but in a normal closing operation, the initial movement of the piston 103 uncovers duct 345 so partially closing valve 325 to restrict the air supply, the movement of piston 335 being sufficient to close duct 347 and keep valve 325 in this position. The breaker has auxiliary contacts 273, 289 which are closed when the breaker is closed, and contacts 317, which close when the breaker begins to open and are in series with contacts 319 of the overload relay 297. Thus when an overload occurs and the breaker trips, contacts 317, 319 energize a reclosing relay 307 which in turn energizes an operating relay 263 which at contacts 261, energizes the electromagnet 117 to produce reclosure. When the breaker recloses, contacts 273 and the closed contacts 278 of relay 263 energize relay 259 which deenergizes 117 and 263 at contacts 257, 267, respectively. A device 321 may limit the number of automatic reclosures or transfer control to a time-delayed reclosing device. When manual closing switch 271 is operated and held closed, the contacts 285 of relay 259 prevent pumping if the breaker at once trips out.