GB182769A - Improvements in and relating to electric relays - Google Patents

Abstract

182,769. British Thomson - Houston Co., Ltd., (Assignees of Brown, H. W.) July 5, 1921, [Convention date]. Electromagnetic switches; protective arrangements.-A sensitive relay adapted to operate in response to current or voltage above or below a predetermined value, or to reverse power, comprises a number of polar projections, a pivoted armature between them, and a winding to control the flux of the armature, the flux path being locally restricted in area so as to be easily saturated, whereby the retentivity of the circuit is reduced and abnormal currents in the winding do not cause reversal of the polarity of the polar projections. As shown in Fig. 1, the pivoted armature 1 is energized by the windings 2 carrying the current of the circuit 7 to be protected and can move towards either the poles 3, 4<1>, or 4, 3 polarized permanently or by a voltage winding 6 on the core 5. Poles 3, 3<1> are of the same polarity and opposite to the polarity of 4, 4<1>. A constructional form is shown in Fig. 2, in which the equivalent parts are lettered as in Fig. 1. The core 5 constitutes an enclosure for the relay, the armature of which has holes cut in it to restrict the flux path and has a pivotal axis at rightangles to the ribbon-wound, two-part winding 6. The armature is controlled by an adjustable spring, one end of which hooks into a hole in a pin 11 extending from the armature. The pin projects through a detachable cover-plate 14 and carries a contact 12 which, when the current in the coils 2 is reversed or reduced below a predetermined value, moves into engagement with the contact 16. By mounting the finger 16 on the opposite side, contact is broken instead of made. Both windings may be voltage-controlled and the magnetic structure may be excited by a constant battery voltage. The armature may be arranged to control a different circuit on either side of the zero position and the spring control may be independent and independently adjustable for the two directions of movement. As shown in Fig. 5, the armature pin 11 carries a contactactuating roller 13 serving to operate one or other of two spring-pressed contact-fingers 23, 23<1> loosely mounted on a screw 26, Fig. 4, and connected to the contact block 29 by the spring 28. The pin has pivoted upon it a control lever 30 moving about the pivot 31 against the action of the spring 34 in one direction and about the pin 32 against the action of the spring 34 in the other direction. With this construction, excess current in the normal direction operates one set of contacts whereas, reverse current operates the other. In a modification, shown diagrammatically in Fig. 8, no separate flux is provided for the armature, but the series coil 46 by increasing the strength of two of the polar projections 41, 41', 42, 42<1> and weakening the other two causes the movement in one direction or the other of the contact-carrying armature. The flux path of the core 43 is restricted by cutting away holes in the core. Specification 172,717 is referred to.