GB307443A - Improvements in or relating to electrical remote control systems or the like - Google Patents

Abstract

307,443. General Electric Co., Ltd., and Clark, H. C. Hannam-. Dec. 6, 1927. Selective distant control systems. - In a system for the selective control and supervision of apparatus at a remote station of the type described in Specification 282,858 wherein a selective signal sent from the control station to the remote station is repeated back to the control station and an operation at the remote station dependent upon the selection is automatically performed only if the signal received corresponds to that sent out, the selective operations of the synchronously operated switches at the control and remote stations are effected by direct current impulses through the intermediary of equivalent alternating current impulses in the line circuit. The line wires may also be employed as power or telephone .lines. Figs. 1 and 2 show the apparatus at the control and remote stations respectively. Relays 56, 74, 73, 79, 57 at the control station and relays 502, 531, 530, 518, 506 at the remote station function in a manner corresponding to similar relays described in Specification 282,858. Thus operation of the selective switches at each station is effected by a system of reciprocal impulse control wherein operation of relay 57 transmits an impulse to energize relay 502 which through the intermediary of relay 506 operates relay 56 over line wires 1, 2 to bring about the transmission of another impulse by relay 57. At each operation of the relay 57 a source of alternating current 303 is coupled to the line circuit 1, 2 through transformers 304, 308, a line balance 309 being provided to ensure that alternating current is not applied to the circuit 310, 311. The alternating current impulses transmitted by relay 57 are applied through a filter circuit 410, 411 to an amplifying valve 419 the plate circuit of which is tuned to the frequency of the source 303 by the circuit 423, 424 and is coupled to a rectifying valve 425. The valve 425 controls the operation of a relay 429 which impulses the direct current circuit 430, 431 including relay 502. At the substation a source of alternating current 403 having a frequency which differs from that of the generator 303 is coupled to the line wires and is controlled by the relay 506 consequent upon operation of relay 502 to transmit alternating current impulses over the line wires to operate relay 329 through rectifying and amplifying valves 325, 319 and filter circuit 310, 311 and thereby control the direct current relay 56. In the normal operation of the system, a selective signal sent from the control station is followed by a signal reverted from the substation and checking the selection. If the correct checking signal is received stepping switches CS, IS occupy similar positions and relays 73, 530 are operated to energize, relays 74, 531 and cause operation of the selected apparatus unit. Synchronization of the stepping switches is effected by relays 79, 518 in a; manner similar to that described in the previously mentioned Specification.