GB773193A - Improvements in and relating to electrical circuit-breakers - Google Patents

Abstract

773,193. Automatic circuit-breakers, switch-cases; protective cut-out arrangements. CHILTON AIRCRAFT CO., Ltd. Sept. 30, 1955, No. 27939/53. Class 38(5) A circuit-breaker has a spring-biased switch arm 4, an arm 9, an unlocking lever 16. and an armature lever 21 rotatably mounted on pivot pins 7, 10, 17, 23, the ends of which are housed in cylindrical recesses 28 ... 31 formed in bosses integral with the two parts of a divided moulded casing. Toggle links 11, 12 interconnecting the arms 4,9 and acting as a normally rigid. strut, hold the switch arm 4 closed on the' depression of a push button 25 which is connected to the pivot 13 between the arm 9 and link 11. When the armature lever 21 is turned about its pivot 23 by an electro-. magnet 26 or a bimetallic strip 27, it releases the unlocking lever 16, which, acting under the bias of a spring 18, collapses the toggle to trip the circuit-breaker. Addi- tional recesses 34 are provided to house a test switch 35 and recesses, e.g. 48, housing the terminals. 2, 1 are so arranged that cable, bus-bar or stud connections may be made to the terminals. Recesses 40 and' projections 32 support a push-button guide 36 and the electromagnet 26 respectively. 'The parts of the casing may be,grooved as indicated at 56 for the releasable attach-' ment of the circuit breaker to a metal clip 58 on a base member 50. The two parts of the casing may be held together by hollow rivets through which bolts may extend to damp a number of circuit-breakers together to form a multipole unit (Fig. 8, not shown). In this case the intermediate pivot pins 14 of the respective toggles would be interconnected for common tripping and the push buttons would be connected by a bar for common operation. Thus in Fig. 17 five single pole circuit-breaker units are interconnected to form a three-phase circuitbreaker in which the three central units are connected between the supply L1... L3 and the load P1 ... P3 and have overload responsive coils b and bimetals 27, the left hand unit has an under-voltage release coil a and the right hand unit has an earth leakage coil c and test switch 35.