GB884450A - Automatic electric circuit breakers - Google Patents

Abstract

884,450. Automatic circuit-breakers. WESTINGHOUSE ELECTRIC CORPORATION. March 21, 1960 [March 25, 1959], No. 9847/60. Class 38 (5). An automatic circuit-breaker has primary and auxiliary trip means, the latter being operable by resetting movement of the closing mechanism when the primary trip is not reset. The circuit-breaker comprises two contact sets each having a resiliently-mounted main fixed contact 19 and an arcing contact 26, these contacts co-operating with movable contacts 23, 28 mounted respectively on channel-shaped arms 24, 29 which are pivoted at 25, separated by a spring 30, and urged anti-clockwise by a spring 33 acting on a pin 38 carried by ends 39 of the arm 24 and slidable in the bifurcated end 40 of a guide 34. The arms 24, 29 are also pivoted at 42 to an insulating- toggle link 41 whose shaft 44 slides in slots 45 of a fixed channel-shaped cam 46 between a lower deadcentre position and an upper position corresponding to closed and open positions respectively. The primary trip comprises an arm 71 pivoted at 67 in the cam 46, urged clockwise by a spring 68, and normally latched by a catch arm 52, the extension arm 72 of the arm 71 engaging the shaft 44 in this position to prevent undesired contact opening due to external shock. The catch arm 52 is pivoted on one end of a shaft 55 and is urged upwardly by a spring 59, the other end of the shaft 55 carrying a similar spring-controlled arm 64 having a contact 62 normally engaging a fixed contact 61, Fig. 4. The arms 52, 64 engage the flange 60 of a plunger 49 controlled by a coil 57 which may be energized by closure of a bimetallic device external to the breaker, Fig. 5 (not shown). The closing mechanism comprises a plunger 75 having steel push plates 76, 77 and controlled by a coil 73 connected in series with a manually-operable switch and the contacts 61, 62, Fig. 5 (not shown), energization of the coil 73 producing downward movement of the plunger 75 which is reset by springs 84, 85 whose ends engage brackets 88, 89 carried by plates 77, 76 and studs 86, 87 mounted on the breaker housing 13. Plates 76, 77 also carry a roller 82 engageable with the arm 72 and a pin 95 on which pivot the ends 93, 94 of a link 92 forming the auxiliary trip means, this link being urged anti-clockwise by a spring 96 to normally engage a rivet 98 on the arm 72. To trip the breaker, the coil 57 is energized to depress the arms 52, 64, movement of the arm 52 releasing the arm 71 which rotates to knock the shaft 44 from the dead-centre position and allow the springs 33 to open the contacts, Fig. 3 (not shown). To reclose, the coil 73 is energized to operate the plunger 75 whose plates 76, 77 depress the shaft 44 and whose roller 82 engages the arm 72 to relatch the arm 71. Should the breaker reclose on to an overload the arm 71 will not relatch and, together with the arm 72, rotates slowly clockwise when the plunger 75 resets, thus allowing the end 97 of the link 92 to engage the shaft 44 near the end of the plunger stroke and so trip the breaker.