Patent GB-351454-A (GB)
Title: Improvements in or relating to electric remote control and supervisory systems
IPC: H04Q9/16
Filed: 1930-03-19
Abstract: 351,454. Distant control systems. STANDARD TELEPHONES & CABLES, Ltd., CHAPMAN, S., and BROWN, A., Columbia House, Aldwych, London. March 19, 1930, No. 8822. [Class 40 (i).] A remote control and supervisory system comprises a central control point, connected by one or more independent junctions to one or more subordinate switching points, each of which is, in turn, connected by one or more independent junctions to one or more switch points, and each switch point having access to a plurality of apparatus to be controlled and supervised, means at the control point, switching points and switch points for the transmission of control and supervisory signals, said means at each switch point being arranged to transmit supervisory signals wherever abnormal conditions, arise in any one of the apparatus accessible from the switch point. The invention is described as applied to a system for controlling the street lamps of a city from a single control point. Switch points SP, Fig. 4 (one only being shown), controlling a number of lamps L are each connected by a pair of lines C such as Cl1, Il1 to one of a number of subordinate exchanges SSC, each exchange by a pair of lines such as CL1, IL1, being connected to a control point CP. The control point contains for each exhange keys K1 .. K8, a stepping switch CS for transmitting over line CL1 control signals in the form of impulses, and a group of three stepping switches SR controlling lamps L1 whereby supervisory signals are received over line IL1. The exchange SSC contains a stepping switch CR controlling the transmission of signals to control circuits SPC, each associated with five switch points, and indicating circuits SP1, controlling the operation of a stepping switch SS, which transmits supervisory signals to the control point. Transmission of control signals. The attendant at the control point, Fig. 1, moves, for example, key K1 to the right for the purpose of lighting a corresponding set of street lamps. A circuit is then completed for relays S1, E, the latter closing a circuit for pendulum relay PM1 which acts to operate and release a rotary magnet RM1 whereby a live switch CS is caused to step. This switch controls the operation of an impulsing relay I adapted to send signals to the exchange SSC. The first four contacts of the switch are unconnected so that the switch may attain uniform speed before impulsing takes place, the next four are connected to earth so that a long pulse may be signalled, every second contact of the remaining contacts is earthed, and the rest are connected to a terminal strip TS2, and thence to a second strip TS1 connected to the keys K1 .. K8. When the wiper of switch CS reaches a contact connected to key K1, a circuit is completed through the upper winding of relay Z, which operates to put earth on the wiper CS1 and prevent further impulsing of relay I. When the wiper returns to the home position a circuit is closed for relay D which operates to break the circuit of pendulum relay PM1 and the locking circuits of relays S1, E, Z. A chain of slow-releasing relays D1 .. D4 is provided so that the line switch CS may not be ready to send out another signal before the receiver at the exchange is in the home position. Reception of control signal. Impulses are received over line CL1. The long pulse at the beginning of the signal operates relay A, Fig. 2, which operates relay B. Relays B, C are slowreleasing relays. At the first break in impulsing, relay A releases, so that circuits are completed for relay C and the rotary magnet RM2. Relay C closes a circuit for the lower winding of two-step relay X. Subsequent impulses step the switch CR corresponding to the signal transmitted. At the end of the signal, relay C releases; causing the relay X to operate fully, whereby, through the wiper CR1, the contact selected is earthed until relav A is released. Release takes place when the sending switch CS, Fig. 1, has returned to the home position. A circuit is then complete for relay W, this relay and the rotary magnet RM2 stepping until the switch CR reaches its home position. The application of earth to wiper CR1 causes a relay such as G1 or HI to be energized. Since the key K1 has been moved to the " on " position, relay G1 will be operated, whereby negative is connected to the leads Cl1 .. Cl5 extending to five switch points. Each point is provided with three relays A1, A2, A3 of ammeter type, each of which has a pointer adapted to close a contact a when carrying no current and to open contacts b when the current rises to about three-fourths of the full-load current. Since negative has been connected to line Cl1, polarized relay P acts to close a circuit for contactor C, whereby a threephase supply MS is connected through the relays A1, A2, A3 to the street lamps L. Transmission of supervisory signals. When the relay P first operates the relays A1, A2, A3 connect the line Il to earth, so that the line Il1 sends back a signal indicating a heavy fault. If all the lamps are in order, the relays open the contacts b whereby earth is removed from line Il1 and the " all correct " signal is transmitted. If any of the lamps have failed one at least of the relays does not open its contacts b so that the line Il1 is earthed through a resistance R causing transmission of a " light fault " signal. Referring to Fig. 2, relays Al, B1 are in series with line Il1. Relay A1 is a sensitive relay adapted to operate when the line is earthed through resistance R, while relay B only operates when the line is directly earthed. Both relays, therefore, operate for a heavy fault, relay A1 for a light fault, and neither relay for no fault. When both relays are energized they lock over a contact of relay T1. A circuit is then complete for relays S1, EE, which lock up. Relay EE closes a circuit for pendulum relay PM2 and rotary magnet RM3, the latter operating line-switch sender SS. To provide for the transmission from, for example, forty switch-points, each capable of sending three signals, a two-digit coding system is employed, the line-switch travelling twice over a bank of contacts, and the wipers being changed between the first and second revolution. The operation of relay S1 through terminal strips TS1, TS2, connects relay X1 to a point on the first bank of contacts so that when the wiper SS1 reaches this point the relay X1 operates to earth the wiper SS1 whereby the impulse train to the control point through impulsing relay I1 is stopped and the first digit is completed. When the switch reaches its last position relay WS is operated whereby impulsing relay I1 is connected to wiper SS2 and disconnected from wiper SS1. Impulsing again takes place until the wiper SS2 reaches a contact which is connected to relay ZZ through contacts of relays A, B. Relay ZZ operates to connect the wiper to earth and complete the second digit. When the switch reaches the home position relay DD operates to release relays EE, X1, ZZ, WS and to stop the pendulum relay and the rotary magnet. Before another signal can be sent slow-releasing relays DD1 .. DD4 are caused to operate and release. Reception of supervisory signals. The signals are received at the control point, Fig. 1, by means of three line-switches, viz. two 5-level switches LS1, LS2, and a single-level switch LS adapted to select which level of one of the other switches will be effective. The operation of the impulsing relay I1 due to the passage of wiper SS1, Fig. 2, over four earthed contacts energizes relays AA, BB, Fig. 1, and the impulses of the first digit are repeated to the stepping magnet SM of switch LS. Relay CC is also operated and remains operated during impulsing, closing a circuit for the left-hand winding of two-step relay XX which operates contact 4. At the end of the digit relay CC releases to remove a short-circuit from the right-hand winding of relay XX which now operates all its contacts. The impulses of the second digit are repeated to the stepping magnet SM1 of switch LS1 and the stepping magnet SM2 of switch LS2 so that the wipers of switches LS1, LS2 operate in synchronism. Relay CC operating in parallel with magnet SM1 causes non-step relay YY to operate contact 4 and at the end of the digit the release of relay CC causes relay YY to operate all its contacts. At contact 3 relay YY connects earth to wiper Q of switch LS and this earth is extended to a wiper of switch LS1 or LS2 according to the position to which switch LS has been set. Assuming that an " all correct " signal has been sent corresponding to the condition of a switch point controlled by key K1, Fig. 1, wiper Q will engage the first wiper Q1 of switch LS1, and this wiper will be moved to its first contact. The earth placed on wipers Q, Q1 by relay YY will be extended over conductor K to relay A1, which locks up over conducting relays C1, B1 to a contact of key K1 in the " on position and lights the white lamp WL. In a similar manner a signal representing a heavy or light fault will light the red lamp RL or the amber lamp SL. An existing indication is cancelled by the arrival of a fresh signal. The switches are stepped to normal upon the de-energization of relay AA.