GB244548A - Improvements relating to automatic electric circuit-breakers - Google Patents

Abstract

244,548. Johnson, E. M., and Metropolitan-Vickers Electrical Co., Ltd. Oct. 9, 1924. Automatic cricuit-breakers.-Automatic circuitbreakers of the loose handle type have each end of the bridge piece or equivalent capable of independent movement, the closing mechanism first moving one end into engagement with its co-operating contact where it is held by tripping mechanism against a spring return after which the other end is brought into engagement with the other fixed contact so that if excess current flows on completion of the circuit the end which was first moved into contact engagement may be immediately tripped to open the circuit. As shown in Figs. 5 - - 7 the bridge piece 3 is carried by a member 6 which on operation of a cam 12 by a handle 11 is moved from the position shown in Fig. 5 to cause the arcing tip 5 to engage a fixed contact 1 the toggle 7 being held in its extended position by an automatic latch 8 as shown in the dotted position in Fig. 6. If the bell crank 13 is now rotated its forked end engages the pivot pin 14 between the member 6 and a pivoted link 9 and causes the lower end of the bridging contact 3 to engage the fixed contacts 2 so completing the circuit. If however on completion of the circuit the current is of a sufficiently high value to operate the overload device the catch 8 is immediately withdrawn and a return spring which may be connected between the pivot 15 and a fixed point causes the toggle 7 to collapse and moves the contact 3 to break the circuit as shown in Fig. 7.