GB520362A - An improved method of and apparatus for the electric selective remote control of definite operations employing synchronously running contact selectors - Google Patents

Abstract

520,362. Electric signalling systems. LANDIS & GYR AKT.-GES. Oct. 29, 1938, No. 31382. Convention date, Dec. 24, 1937. [Class 40 (i)] In a system employing synchronously driven switches at the transmitter and receivers, each receiving switch is associated with a relay group which responds to all signals including disturbing impulses and prevents the final response of the receiver unless the relay group has been set exclusively by the signals appropriate to the receiver. In the receiver shown, the effective control operation is performed by a two position relay M operated by energization of one or other of its windings N, O. Closing of the circuit at m is effected in response to start, selecting and operating signals over contacts 1, 2, 4 of the switch F, and opening of the circuit in response to similar signals over contacts 1, 3 and 4. The start signal (A.C. as shown) operates E whereupon synchronous motor G drives the switch and holds itself over g for a revolution. A selecting signal arriving when switch F is on contact 2 energizes H which - holds itself, opens the circuit of winding O and closes a point in the circuit of winding N so that if no further signal arrives other than the operate signal on contact 4, winding N is energized and closes contact m. Any extraneous signal element either operates selector relay K over contact 3 to disconnect winding N or operates a protective relay L over contacts 5, 6, 7 which are not connected to selector relays, whereupon the circuit of both windings N and O are opened. Lack of synchronism also prevents a final operation. In a modification, Fig. 2 (not shown), four selecting relays are used to control two two-position relays, immunity against incorrect signals being obtained by a protective relay similar to L, Fig. 1, and by a counting relay set controlled over a second contact bank of the switch so that an excessive number of signal elements releases all the operated selecting relays. In a further modification, Fig. 3 (not shown), the counting set and additional contact bank are replaced by a checking relay controlled either in open circuit or in closed circuit by contacts of the selecting relays and disabling the two-position relay circuit if more than the correct number of selecting relays has been operated. The signalling may be effected by superimposition of A.C. or D.C. impulses over a supply network, or by variation of current of a supply network, the selector relays being sluggish to prevent response to momentary interruption of the network.