GB372435A - An improved device for the periodic opening or closing of an electric circuit - Google Patents

Abstract

372,435. Selectors responsive to code signals. SIEMENS BROS. & CO., Ltd., Caxton House, Tothill Street, and HUM. PHRIES, H. E., 47A, Lewisham Hill, both in London. Feb. 17, 1931, No. 4995. Addition to 334,516, [Class 40 (iv), Telephones &c.]. [Class 40 (iv).] In a'device for periodically opening and closing an electric circuit described in the parent Specification modified for operation on low-voltage circuits a polarized relay Z, Fig. 1, is employed which is of the type which maintains its armature in the position to which it is brought when the relay is energized. In the position shown a current flows from earth over contact y<2>, condenser QA, choke ZC, and contact y<1>. As the condenser charges up, the rise of current is delayed by the series connected choke ZC and when the voltage across the condenser has risen to a sufficiently high value the relay Z operates, closing the circuit of relay Y. The contacts y<1>, y<2> are changed over and the current through the relay Z and choke ZC is reversed. The contacts y<1>, y<2> are of the make-before-break type so that during the period when they make both front and back contacts a path is closed including the choke and the relay allowing the energy stored in the choke to be dissipated, so delaying the release of the relay. Condenser QA also discharges through the relay coil with the same effect, but the predominating effect is the dissipation of energy stored in the choke. The flow of current through the relay in the reverse direction is consequently delayed, so delaying the initiation of the operation of the relay in the reverse direction. The de - energization of the relay does not affect relay Y but when it is operated by current in the reverse direction contact Z<1> is opened and relay Y is released, restoring its contacts y<1>, y<2> to the position shown. Thus a periodical delayed action opening and closing of a controlled circuit is produced. In a modification (Fig. 2, not shown), in which ordinary change-over contacts yl, y2 are employed, the choke ZC is divided, a condenser being connected across a portion of the choke and the condenser directly shunting the relay is dispensed with.