Patent GB-222864-A (GB)
Title: Improvements in remote control systems for electrical substations and other distribution systems
IPC: H02J13/00
Filed: 1924-09-30
Abstract: 222,864. Metropolitan-Vickers Electrical Co., Ltd., (Assignees of Wensley, R. J.). Oct. 1, 1923, [Convention date]. Selective distant-control systems and apparatus; tell-tale apparatus.-Apparatus at an electric power substation is selectively controlled and controls indicating lamp signals at a main station by means of code signals of audio-modulated highfrequency current. The main station A, Fig. 12, and substations B, C have a transmitting antenna 1202 and receiving antenna 1213 arranged in proximity to a power transmission line 7. Code transmission for signalling or controlling is initiated by the closure of a contact such as 1206, 1207 for which a switch F then hunts. The radio transmitter 1201 then sends out an audio-modulated wave and a code sending switch CD moves step-bystep through its twenty-five points, pausing in two positions determined by the setting of the switch F. At each step the modulation is interrupted and these interruptions are interpreted by the receiver 1212 at the distant station as interruptions in the circuit of a relay controlling a selector H. The latter is thus moved step-by-step in the same way as the switch CD and selects a relay in each of two groups to control the necessary operation. A controlling signal is arranged to be repeated until the corresponding indicating signal has been received from the substation. Radio - telephonic communication is provided for between anv two stations. In the case of a call from one substation to another the calling station alters the tuning of his radio transmitter and receiver to correspond with that of the main station, since the transmitter and receiver at one station work on different wave lengths. A further arrangement is provided for preventing interference in the receivers bv the local transmitter. All the step-by-step switches are of the type that takes a step on the release of the driving magnet. Control and operation of substation code - sending switch, Figs. 9 and 10. In outline the operation of the switch to signal the closing of contact 946 is as follows. Relays 920 - - 922 complete a starting circuit for the hunting switch F1, and mark a terminal on the bank of its wiper 1014. The switch F1 on reaching the marked terminals energizes a relay 1028 to start the radio transmitter, and a relay 1001 for repeating impulses to the transmitter, completes a starting circuit for the sending switch CD1 and over wipers 1012, 1013 marks two terminals in the bank of wiper 1056 of the sender. The terminal marked by wiper 1012 depends on the position of relay 922, which would not be energized if the opening of contact 946 were being signalled. The sender then operates under control of a sluggish stepping relay 1033 to move to the first marked terminal, where a pause occurs determined by the sluggish relapse in succession of relays 1032, 1031. At each step the repeating relay 1001 is released by the driving magnet 1034. After the pause the sending switch moves to the second marked terminal, pauses again and then moves to its twenty-fifth terminals. After an interval the repeating relay is disconnected and the sending switch moves on to normal and relay 1028 is then released to disconnect the radio apparatus. The switch F1, however, remains in its set position. The switch may be controlled by the Kelvin balance ammeter A shown at the bottom of Fig. 9 to signal the load on the substation. The contact 933 is moved in accordance with the load and selects groups of three relays such as 942 - - 944 which have similar functions to those of the relays 920 - - 922. In detail the operations are as follows. Relay 922 energizes relay 921 and locks up relay 920. Relay 921 starts the driving magnet 1004 of switch F1 and marks terminal 1018. When the terminal is reached relay 1028 pulls up over it, disconnects 1004, energizes stepping relay 1033 and relay 1027 which energizes relay 1026. Relay 1026 energizes relay 1030 which energizes relay 1032 which energizes relay 1031. Driving magnet 1034 pulls up over wiper 1057 and releases 1033 which releases 1034, whereupon the wipers move one step and 1033 pulls up again re-energizing 1034. This inter-action continues until wiper 1056 reaches a terminal connected to ground over wiper 1013, whereupon relav 1002 pulls up and causes successive relapse of sluggish relays 1032, 1031. Magnet 1034 then energizes again and is again released by 1033 to move the wipers one step, whereupon 1002 falls back and 1031, 1032 pull up again and stepping proceeds until the terminal marked over wiper 1012 is reached. A pause then occurs as before and the ordinary stepping circuit is reestablished and is maintained until the twenty-fifth terminals are reached. Relav 1034 no longer has a circuit over wiper 1057 and remains back, and wiper 1055 releases relay 1027. The armature of this relav makes several oscillations before coming to rest midway between its contacts, and thus produces a time interval before the relapse of the sluggish relays 1025, 1026. Relay 1025 is arranged to fall back first and energizes relay 1003 over a contact of relay 1029 which energized when wiper 1055 reached the final terminal. Relay 1003 locks up 1028 and short-circuits relays 920, 921 over wiper 1011. Shortly afterwards 1026 falls and releases 1001 and 1030, the latter releasing 1032 and 1031 and completing a circuit 1048, 1034, 1048, 1058, 1052 for driving the sending switch to normal by self-interruption. Relay 1029 then falls and releases 1003, which releases 1028 and removes the shortcircuit from 921, 920. The former pulls up again and locks but the latter remains back. Control of substation radio transmitter, Fig. 11, by codesending switch. Relay 1028, Fig. 10, on pulling up energizes relay 1160 which energizes relay 1154 to connect the alternating current main A.C. to the filament-supply transformer 1133 and to supply the mercury rectifier 1142 for feeding the plates. The highfrequency generating tube 1109 then feeds the antenna 1101 with unmodulated continuous waves. The energization of relay 1001, Fig. 10, energizes relay 1127, which connects one winding of transformer 1125 in the grid circuit of the tube 1123. Since the other winding is in the plate circuit this tube now generates audio - frequency currents which influence the modulating tube 1115. Each relapse of relay 1001 releases relay 1127. The movements of the code switch are thus reproduced as interruptions of the audio-modulation of the radiated wave. After the code has. been sent relay 1127 remains energized for a time and then falls back, and after a further interval relay 1160 falls and releases relay 1154 to cut off the power. Reception and translation of radio code signals. Signals picked up by the antenna 305, Fig. 3, are detected by the tube 309, amplified by the tube 318 and then fed to a tube 329 arranged as a rectifier with a relay 335 in its plate circuit. This relay is energized bv the normal plate current but falls back when audio-currents are flowing in the transformer 326, and thus repeats the movements of relay 1001 in the code-sending equipment. Operation of selector. Fig. 5, bv received signals. The relapse of relay 335 when modulated waves are first received energizes relay 507 which energizes relay 505 and stepping magnet 523. At each energization of relay 335 relay 507 falls back and the wipers take a step. Relay 505 is made more sluggish than the stepping relay at the sending switch and holds up until the end of the code. Relay 504 is energized prior to the first train, and during it holds up over a back contact of the line relay and maintains the circuit of a relay 501. At the end of the train relay 504 falls back and is replaced by relay 503 which first energized in positions 12 - - 14 of the wiper 531. The third train moves the wipers to their twenty-fifth terminals, in which position wiper 533 releases relay 502, and after an interval relay 507 falls back permanently and releases relay 505, which completes a restoring circuit for the stepping magnet over its interrupter contact and wiper 532. Selection and display of signals, Fig. 4. Relay 505 in the selector on pulling up grounds wire 548, and relay 482 is energized and locks up. The4 off-normal relay 506, when the selector moves, grounds wires 549, 550, and relay 470 pulls up and locks itself over the key K1 to light an alarm lamp 473 and sound an audible alarm (not shown). The relapse of relay 504 at the end of the first train energizes one of the relays 408 - - 411 as determined by the position of wiper 530, and the selected relay locks to relay 506. The relapse of relay 503 after the second train similarly energizes one of the relays 404 - - 407. When relay 502 falls as the selector reaches its final position ground is connected over wire 560 to relay 480. In the case of ordinary signals this has the effect of energizing or shunting out one of the relays 400 - - 403, which accordingly extinguishes one and lights the other of the lamps that it controls. Changes of load are indicated by the lamps L1. Relay 438, which is energized by the selected one of the relays 408 - - 411, unlocks the relays 435 - - 437 to cancel the previous indication, and when ground is connected over wire 560 another one of these relays pulls up in series with relay 480 and locks up. Relay 480 unlocks relay 482. Main station code-sending arrangements, Fig. 1. Each apparatus unit at the substations has a double throw-key K in the main station for controlling it to move in one or other direction, and each of the keys controls a pair of relays 105, 106, one of which locks up according to the direction of throw. The relays such as 106 energize a relay 108 to switch over the control of the second train of impulses from wiper 124 to wiper 123 of the hunting switch F. The original circuit of relays 105, 106 goes over a contact of the relay 400, Fig. 4, controlling th