Patent GB-351387-A (GB)
Title: Improvements in and relating to remote control and remote supervision systems
IPC: H02J13/00
Filed: 1929-12-23
Abstract: 351,387. Distant control systems. INTERNATIONAL GENERAL ELECTRIC CO., Inc., 120, Broadway, New York, U.S.A.-(Assignees of Allgemeine Elektricitats-Ges. ; 2, Friedrich Karl-Ufer, Berlin.) Dec. 23, 1929, No. 39283. Convention date, Dec. 22, 1928. [Class 40 (i).] Control and supervisory signals transmitted over a common channel between a central control point and a distant substation consist of a constant total number of impulses divided into two series which are routed by means of a chain of slowrelease relays to different step-by-step switches. The receipt of a control signal is acknowledged by the sending back of a single inpulse and this is followed by a supervisory signal corresponding to the new position of the substation apparatus which has been controlled. If no acknowledging impulse is received the signal is repeated once and if there is still no acknowledgment an alarm is given at the control station and the sending apparatus freed for further signals. Means is provided by which in response to enquiry signals transmitted from the control station, signals indicating the positions of all the apparatus at the substation are sent back in succession to the control station. In the system shown the common channel is a single conductor with earth return but alternatively a high-frequency carrier wave of a single frequency or with a single modulation may be used. Figs. 2 and 3 represent associated transmitting and receiving apparatus suitable for either the control station or a substation and including all apparatus which may be required at either. The transmission of impulses is controlled by a step-by-step switch 9 and the constant total number of impulses (twelve) corresponds to the number of steps in the bank of the switch. Transmission of control signal from central station. The movement of switch 1 to the right closes a circuit at contacts 2 for relay 5 which connects negative battery to lead 6 over back contacts of receiving relays 53, 52, 51 so that relay 7 and the right-hand winding of relay 11 are energized. Relay 7 connects up relay 10 which on operating short-circuits itself and operates the magnet 14 of switch 9. The wipers I, II of switch 9 are thus stepped round and at each operation of magnet 14 a circuit is completed for the righthand winding of relay 13 which transmits an impulse over the line A, B. The receiving apparatus at the control station is prevented from responding to these signals by the inclusion of a back contact of relay 13 in the circuit of relay 50. When switch 9 takes its first step a circuit is completed over its wiper II and a wiper I of a further switch 15 for a relay 16 which in turn operates the stepping magnet of switch 15. The switches 9, 15 thus move in synchronism until the eighth position is reached when a circuit is completed over contacts 3 of switch 1 for the left-hand coil of relay 11 which opens the driving circuits for both switches 9, 15 and closes a circuit for a slow-operating relay 17. After a predetermined interval the operation of relay 17 re-drives switch 9 but switch 15 remains in the eighth position. When switch 9 arrives at its normal position, contacts 8a reclose the circuit for relay 7 which operates after an interval if no acknowledging signal has been received and initiates the repetition of the control signal. Receipt of control signal at substation. Impulses are received by relay 50 which repeats the first series to the magnet of switch 55. Slow-release relays 51, 52, 53 operate in turn and during the pause at the end of the first series relay 51 relapses and operates relay 54 which directs the second series of impulses to the magnet of switch 56. At the end of the second series relays 51, 52 release and a circuit is completed over wipers 55, 56 for a relay 57 controlling, say, an oil switch. On the relapse of relay 53, switches 55, 56 return to normal. Acknowledgment of signal. The circuit of relay 57 includes the left-hand winding of substation relay 13 which operates to transmit an impulse to the control station at which relay 50 causes switch 55 to advance one step. This effects the operation over wiper III of switch 15 of a magnet 18 which unlocks the switch lever 1 causing the release of all operated relays at the control station and the closure of a restoring circuit for switch 15. No acknowledgment; indicating a fault. If contact 2 is not opened by the release of lever 1 the control signal is repeated and if at the end of the second signal there is still no acknowledgment a slow-operating relay 19 advances switch 15 one step, to prevent further repetition of the signal, and completes a circuit for a drop-indicator 20 which in turn operates a lamp 21 and a buzzer 22. Switch 15 is further advanced to normal under the control of a further rotation of switch 9 and other control signals may then be transmitted. Transmission of supervisory signal to control station. When an oil switch 23, Fig. 3, at the substation changes its position and closes, say, contact a, a circuit is completed over contacts e of relay 26 for the left-hand winding of relay 27, contacts a, c of which in conjunction with similar contacts of relay 26 act in a similar way to contacts 2, 3 of switch lever 1 to control the transmission of a signal to the control station. The acknowledgment signal causes the energization of the right-hand winding of relay 26 to prepare the circuit for the transmission of the next signal. Lamps 24 controlled by a manual switch 25 may indicate at the substation the occurrence of a change in condition of the oil switch 23. Receipt of supervisory signal at control station. One of the windings of relay 59, Fig. 2, is operated in parallel with a drop-indicator 60 which sounds a buzzer 61. The operation of relay 59 lights an appropriate lamp 62 over a manual switch 63 which is moved after each signal in preparation for the next. Signalling position of all substation apparatus. In response to particular signals from the control station the relays 28, 29 at the substation may be operated. Relay 28 energizes the left-hand windings of relays 26 so that all oil switches with the a-contacts closed will give signals in succession. Relay 29 similarly causes all switches in the opposite condition to give signals.