Patent GB-485308-A (GB)
Title: Improvements in or relating to electrical systems of remote control
IPC: H02J13/00
Filed: 1937-02-04
Abstract: 485,308. Electric control systems. GENERAL ELECTRIC CO., Ltd., and KAHL, A. R. Feb. 4, 1937, No. 3356. [Class 40 (i)] In a system for the remote control of groups of different apparatus such as street lamps, shop signs, tariff meter changing gears, &c., the control is effected over a power network by synchronously driven switches at the control and controlled points. The system shown provides for the control of one of a group of signs, Fig. 3, and the lights K, M, Fig. 2, of a group of street lights from a control station, Fig. 1, over the power mains PA, PB, PC. Motor-driven switches CT, CU are provided at the various switching points and are started by and rotate in synchronism with the control station switch CS. Groups of switches are selected for operation in accordance with the frequency of a " starting " pulse sent out by the switch CS. The switch CS is connected to a plug board comprising bars TB1 .. TB5 connected to the bank contacts and bars CB1 CB4 connected to relays A .. D which control the output frequency of a voice frequency generator FG. The bars are adapted to be interconnected by plugs P1, P2 in accordance with the nature of the control to be effected. The plug P1 facilitates the transmission of group selecting and starting signals for the motor-driven switches at the switching centres and the plug P2 or several similar plugs determine the transmission times in the cycle of operations of further frequency pulses for effecting desired operations at the switching centres. When it is desired to transmit a signal a key ST is operated to start the motor MA which closes cam contacts CM1 to maintain the driving circuit during one revolution of the switch CS. The switch in moving over its initial contacts pulls up a relay in the group A .. D to transmit a characteristic pulse over the network. The pulse pulls up correspondingly tuned relays such as FA, FB to start the associated synchronous switches. These switches close cam contacts such as CN to maintain closed the driving circuits of the motors and prepare operating circuits over the wipers of the switches for operating units such as KA. A unit is operated upon response of the relay FA to the pulse which is spaced in the time cycle by the control plug board. Several operations may be effected during one cycle by correspondingly spaced pulses. Fig. 3 shows an alternative control arrangement wherein the cam contacts CO prepare the circuit of a tuned relay TE operated by rectified current received directly over the mains to close the circuit over the wiper of the switch. In this arrangement also a relay KC may be pulled up and locked by one signal and released by a short-circuit produced by another signal. A plurality of groups of different apparatus may be selected by the transmission of an initiating impulse composed by a plurality of frequencies. In a modification only one frequency is used, sections of the contact banks of the switches being allotted to different types of control operations. The system may be used in association with D.C. networks. Specifications 22087/03, 2132/07, [both in Class 40], and 209,815, [Class 40 (i)], are referred to.