ES346888A1 - Current limiting circuit breaker mechanism - Google Patents

Abstract

The contact rod 37 of an automatic circuit breaker is decoupled from an operating mechanism by current responsive means so that the contacts can move rapidly to open position independently of the operating mechanism, providing a current limiting action. An operating handle 44 is coupled to a forked lever 48 by overcentre tension springs 49. A stud 60 on a pivoted plate 58 co-operates with the forked lever 48 so that as handle 44 is moved plate 58 snaps from one position to another. A pivoted member 66 is coupled to the contact rod 37 and has pins 69, 70 projecting into a slot in plate 58. A spring 72 normally holds pin 70 in the downturned end of the slot so that member 66 moves with plate 58 to open and close the contacts as handle 44 is moved. If a heavy overcurrent occurs an electromagnet (29) (Fig. 1, not shown) draws the rod 37 rapidly to the left spring 72 is overcome and pin 70 moves out of the end of the slot thereafter spring 72 is effective to draw member 66 and the contacts to the left to fully separate the contacts. The contacts have a degree of overtravel such that they do not separate until pin 70 has left the end of the slot so that once they separate the contacts must move to the fully open position. If a small overcurrent occurs a bimetal strip (24) (Fig. 1, not shown) releases a latch 62 to trip the operating mechanism in the usual manner.