GB208731A - Improvements relating to automatic electric switches - Google Patents

Abstract

208,731. Cox, F. B. June 20, 1922.. Automatic circuitbreakers. - Loose-handle automatic circuit-breakers have a rectilinearlymoving contact-carrying rod A with springs a<1>, tending to move it to the " off " position. In addition to these springs quick make and break mechanism of the type described in Specifications 23162/11 and 23107/14 may be provided. The operating mechanism consists of a lever C pivoted at c<2> and connected by links D<2>, D' pivoted together at d to one arm b<3> of a bell-crank lever pivoted at b<2>. The other arm B is connected by links b<1> to a block a<2> sliding on the rod A and carrying a pin a<3> which moves on a slot a<4>. In closing the switch the arm C is rotated to the dotted position shown in Fig. 1, allowing projections d<2>, d, to engage so that the links D<2>, D<1> act as a strut between the arm c' of the lever C and the arms b<3>. The pin a<3> is thereby moved to the bottom of the slot a', taking up the lost motion, after which the switch closes. In its final position the arms C and D<2> form an overset toggle, the switch springs holding the arm C against a stop c<3>, Fig. 3. Pivoted at e<1> to the rod A is a lever E with an enlarged head e<5> and carrying at e<2> the core f<1> of a no-volt magnet F. A spring e<3> is connected between the point e<2> and a fixed point e<4> so arranged that during the closing motion of the rod A the line of action of the spring crosses the axis of the rod E, the switch contacts being arranged to engage slightly before this takes place so that when the switch is closed (Fig. 3) the rod E is maintained by the electromagnet F against the action of the spring e'. When the electromagnetic force falls sufficiently due to diminution or failure of the supply voltage the rod E is moved to strike the rod D<2>, collapsing the strut D<2>, D', and allowing the switch to be opened by the springs a<1>. Alternatively the no-volt armature f<4> may be attached to the end of the rod E as shown in the dotted portion of Fig. 1. The switch may be opened mechanically by backward movement of the handle C. Alternatively, as shown in Fig. 5, the arm c<1> is separated from the handle C which has a projection c<6> for engaging the end c of this arm. A spring c<4> tends to pull off the arm c<1>, but this is normally overcome by the force produced by the springs a<1> on the toggle c<1>, D<2>. In a further alternative the arm C is retained by a pivoted catch connected by a link to a spring-controlled bell-crank lever which is depressed by the arm B as the switch is closed. The handle may be moved laterally to disengage this catch. Adjustable overload electromagnets may be arranged to short-circuit the coil F so as to trip the switch on a predetermined overload.