GB593601A - Improvements in remote control systems - Google Patents

Abstract

593,601. Selective control. BRITISH THOMSON-HOUSTON CO., Ltd., and MOIR, J. June 8, 1945, No. 14495. [Class 40 (i)] A remote control system comprises a number of relays 1, 2, 3 which are connected in series, Fig. 1, or in parallel, Fig. 2 (not shown), with a supply 4. The current flowing through the relays is insufficient to operate them, but sufficient to maintain them in that position when they have operated. The operation of a " push-button " switch A, B or C, Fig. 1, situated at a remote point, momentarily shortcircuits all but the appropriate relay which operates due to the increase of current. Any relay which has previously operated "dropsout" when it is short-circuited. When a large number of relays are to be controlled, a non- linear resistance 10 is connected in series with the relays. The relays may be controlled from more than one point by connecting switches such as A1, B1, C1 in parallel with the switches A, B, C. In a modification, Fig. 2 (not shown), a number of parallel branches, comprising a preferably non-linear resistance 10 connected in series with a common resistance across the supply. The operation of a switch A, B or C short-circuits the individual resistance and the appropriate relay operates. The short-circuiting of the resistance causes the voltage across each branch to fall, thus any previously operated relay "drops-cut."