Patent GB-176547-A (GB)
Title: Improvements in electric circuit breakers and the like
IPC: H01H71/24
Filed: 1920-12-20
Abstract: 176,547. Bolton, R. A. R., and Bacon, H. Doc. 20, 1920. Automatic circuit-breakers; electromagnetic switches.-In circuit-breakers of the type in which the forces producing the opening movement are due, wholly or in part, to the interaction of the current in a conductor formed or carried by the movable element of the breaker and a current in an adjacent conductor or conductors, the currents in the two interacting conductors are arranged to flow in the same direction and the circuit is broken by the resulting attractive action between them. A third conductor, on the opposite side of the movable conductor, may be arranged to carry current in the opposite direction so that the resulting repulsion may assist the circuit-breaking action. In the construction shown in Figs. 1 and 2, the movable contact bar D is pivoted at F and carries an armature C cooperating with a U-shaped magnet A. The fixed contact arm J which may be a yielding contact pivoted at L, is nearly parallel to the movable contact-member. The current, entering at F, passes through the breaker and through a straight conductor or a number of turns B of conductor parallel with the movable contact-member, and, finally, through a blow-out coil H. The adjacent conductors D, B carry current in the same direction and, consequently, the interaction between them tends to move the arm D to the off position. A force in the same direction is produced by the repulsive action of the conductor J on the contact-member, the currents in this case being in opposite directions. The circuit-breaker may be closed electromagnetically by a shunt coil N under the control of a push-button R and maintained by a reduced shunt current through the resistance S introduced by the auxiliary contact switch Q which may close, automatically, when the circuit-breaker closes. The circuit-breaker need not entirely break the circuit; the contacts may be shunted by a resistance T. The blow. out magnet is excited from an independent source as well as by the coil H, the coil H serving mainly to counteract the demagnetizing action of the current through the contacts E, G. The circuit-breaker may reset itself automatically by providing that the auxiliary switch arm Q closes the push-switch R when the circuit-breaker fully opens. Latches and detents may be employed as desired, for example, to hold the contact-member in the open position. In the modified construction shown in Fig. 3, the armature C is dispensed with and the cores A, M are united to constitute a single closed core on which windings Y, Y<1>, corresponding to the windings B, N, are wound to form consequent poles at the air gap in which the contact-carrying conductor W is arranged to be attracted by one of the windings and repelled by the other. The contact arm W may be in the form of a coil, the otherwise idle exterior turns of which may be located in the gap of a second closed core which may be incorporated with the first. The contact arm W is made as light as possible in order to reduce the moment of inertia of the moving parts to a minimum.