GB684311A - Improved trip-free electric circuit breaker - Google Patents

Abstract

684,311. Automatic circuit-breakers. HEINEMANN ELECTRIC CO. Aug. 8, 1947 [April 6, 1939], No. 21963/47. Class 38 (v) In a trip-free circuit-breaker having a rigid moving contact bar, a wiping action at the contacts is obtained by providing the bar with an inclined slot for its pivot pin. The circuit-breaker comprises an L-shaped frame 1 having integral ears 3, 4, the ears 3 having slots 6 to receive the pivot pin 7 which passes through an inclined slot 9 in the switch bar or arm 8, whilst the ears 4 have bearing apertures 26 to receive the pivot pin 25 of the switch handle 24 and apertures 33 for the pivot pin of an armature. The switch arm is biased towards the open position by a spring 12 and is moved by the handle 24 through the medium of toggle links 13, 30, the links being normally latched in their extended position by means of a projection 27 abutting the arm 28<SP>1</SP> of a U-shaped member 28, Fig. 9. This arm 28<SP>1</SP> has a flat surface 28<SP>11</SP> which permits the passage of the projection 27 when the member 28 is turned about its arm 28<SP>1</SP> to trip the switch. The frame 1 supports an insulating tube 40 on which the trip coil 43 is wound. At the end of the tube is a fixed pole piece 46 and within the tube is a closely fitting spring loaded core 44. The armature 31 is spring biased and has a limb which co-operates with the pole piece 46 and the pole 2 formed by the end of the frame 1, and a limb 34 which may engage the limb 28a of the member 28. The circuit breaker is closed manually and may be opened manually by means of the handle 24 which moves the switch arm about the pivot 7 by means of the latched toggle links 13, 20, the slots 6, 9 which are inclined at different angles, causing the contact surface 62 of the arm 8 to slide on the fixed contact 61 when the switch is closed. When the switch is opened a similar sliding movement is obtained, and if the contacts have welded, the impact of the pin 7 against the ends of the slots 6 creates the shock necessary to break the weld. Under heavy overloads the magnetic field set up by the coil 43 attracts the armature 31 to trip the circuit breaker by breaking the toggle as the limb 34 turns the member 28. During more moderate overloads the flux of the coil 43 is not sufficient to trip the circuit breaker until the core 44 has been drawn into the coil to improve the permeability of the magnetic circuit. As the core 44 closely fits the tube 40 the air or oil in the tube will retard the movement of the core and impose a time delay which will vary inversely with the strength of the current. The fixed contact 61 consists of a conducting strip 58 wound around an insulated core 60 between magnetic blow-out plates 63. A stop 37 limits the outward movement of the armature. Specification 684,327 is referred to. The Specification as open to inspection under Sect. 91, also included the subject-matter of Specification 684,390. This subject-matter does not appear in the Specification as accepted.