Patent GB-835332-A (GB)
Title: Improved electrical control system and apparatus
IPC: H04Q9/16
Filed: 1957-09-23
Abstract: 835,332. Electric remote control systems. SHAND & JURS CO. Sept. 23, 1957 [Oct. 31, 1956], No. 29890/57. Class 40 (1). An electrical system is arranged to indicate and control the state of a remotely located variable having two possible states. Selection.-A control and reading station 11, Fig. 1, sends a number of pulses determined by the remotely situated control unit to be selected to a remote selector 12 to cause it to select the desired remotely situated unit which may be a liquid level transmitter 14, temperature transmitter 16 or remote control unit 17. As described in detail, a control and reading station, Figs. 2a-2c, is connected by a terminal T11 to a remote selector 12 which may be of the type described in Specification 826,384 and which is connected to a remote control unit, Figs. 3-6 (only Fig. 6 shown). The remote selector 12 normally applies a potential to the terminal T11 thereby keeping a relay L energized and hence a lamp 29 lit. In this state, depression of a start button 27 energizes from a D.C. supply 26, a relay K which locks and applies a negative potential to the terminal T1, T3. A relay A, Fig. 2B, is thus energized over the terminal T1 to start an A.C. motor 41 which commences to rotate a square cam 42 to cause periodic opening and closing of pulsing contacts S5. The energization of the relay A also applies a negative potential from the terminal T1 to the contact 4 of the switch S5 so that when the contacts 3; 4 of the switch S5 are closed, a relay B is energized and holds. Closure of the contacts 6, 7 of the relay B causes pulses to be sent via the pulsing contacts 1, 2 of the switch S5 over the terminal T11 to the remote selector 12. Closure of the contacts 4, 5 of the relay B energizes a step coil D for a stepping switch S3 which advances one step on de-energization of the coil D. The switch S3 is thus advanced one step for each pulse sent out over the terminal T 11 until the wiping contact of the switch S3 is earthed through a selected contact, as shown the first contact, of the wiper switch S2. The relay B is thereby shunted out and de-energizes, so that its contacts 3, 4 close and the switch S3 steps rapidly to its contact 51 where it stops due to the removal of its stepping coil D from the circuit. If a power failure should have occurred, however, relay A will be de-energized and its contacts 1, 2 will be closed so that stepping will continue to the home position at the contact 52, but normally arrival at contact 51 applies an energizing potential over the contacts 2, 3 of the relay A to the relay C which is energized and holds. The contacts 3, 4 of the relay C then open to de-energize the relay A thereby stepping the switch S3 to its contact 52. The closure of the contacts 5, 6 of the relay C results (i) in the energization of a sluggish relay T to control a start pulse, (ii) in the energization of the coil N of a switch S1, and (iii) in the energization of a relay O. The contacts 4, 5 of the relay O close to place a motor 51 in circuit, the motor circuit being maintained through the contacts 1, 2 of a switch S22. Cam 53 is also operated and renders inoperative the lamp 29 and start button 27. A start pulse is then sent over the terminal T11, the pulse terminating when the contacts 1, 2 of the sluggish relay T open. Confirming selection.-The energization of the step coil N causes the wipers of the switch S1 to be stepped to contacts 2. The start pulse is received over the line 801, Fig. 6, and energizes a relay W which holds and closes contacts 9, 10 to start a motor 752. Confirming code pulses are generated by a code disc 783 which periodically earths the line 801, the first earthing operating the relay L which causes a pulse through the contact 2 of bank 1 of the switch S1 to energize the step coil E and advance a switch S4 from contact 0 to contact 1. Relay P is also energized over the contacts 1, 2 of the relay L. The relay L is de-energized when the earthing of the line 801 through a conducting segment of the code disc 783 terminates. Thus the relay L follows the pulses and the switch 84 is advanced one step for each pulse. As shown, only one pulse is required and engagement of the wiper of the switch S4 with its contact 1 earths one side of a relay F. If selection has been correct, the relay F will not be operated, but if selection has been incorrect, the relay F operates to reset the apparatus and light the warning lamp 45. After completion of the transmission of the confirming pulses, the motor 752 continues rotation of the cam 786 to operate a timing switch S26 which through its contacts 10, 11 forms a holding circuit for the motor. The relay W is now energized when the contacts 1, 2 of the switch S27 close. The switch 804 is open or closed depending on the state of the remote apparatus connected to the remote control unit 17. If the switch 804 is closed, a steady pulse is sent over the line 801, but if the switch 804 is open a series of pulses is sent over the line 801 by the periodic grounding of this line via the switch S27 and the line 807, and in both cases the current is insufficient to operate the relay W. After transmission of the confirming code pulses, the sluggish relay P releases to energize the step coil N which advances the switch S1 by one position to its contact 3. This earths one side of the relay F which lights the lamp 45 to indicate faulty operation if the other side has not been earthed as described above. Indicating remote state.-If selection has been correct, and the remote state is with the switch 804 open, then pulses sent to the control station 11 periodically operate the relay L to cause operation of a relay Q over the contacts 1, 2 of relay L and contact 3 of switch S1. The relay Q establishes a holding circuit over its contacts 3, 4 and operates a time delay device TD-5 over its contacts 7, 8. The pulses received from the remote control unit are passed via the terminal T54 and the contacts 5, 6 of the relay Q to the condenser 58 which discharges between pulses to energize a relay R and light a lamp 61. If, however, a steady pulse is transmitted, relay R is not energized owing to the presence of the condenser 58 and the lamp 62 is lit. Changing remote state.-Closure of the control button 59, Fig. 2C, energizes the relay W at the remote control unit to energize a relay U over the contacts 1, 2 of the relay W. On release of the control button 59, the relay W is deenergized and a relay V is energized over contacts 1, 2 of the relay U. The contacts 5, 6 of relay U and 4, 5 of relay V may be adapted to control various apparatus. The relays U, V are maintained energized until a second closure and release of the control button 59 returns them to their original state thereby changing over the control contacts 5, 6 of relay U and 4, 5 of relay V. Resetting.-After a suitable control period such as 16 seconds the time delay device TD-5 operates to de-energize the relay K over terminals. T14. This removes potential from the D.C. supply 26 to the terminals T1, T3 to deenergize the relays T and C. The de-energization of relay T opens its contacts 4, 5 to de-energize the time delay devices TD-1, TD-2, and the de-energization of the relay C closes its contacts 9, 10 to provide a circuit for energizing the step coil E which advances the switch S4 to its home position when the circuit is broken by the offnormal contacts of the switch S4. De-energization of the relay K closes its contacts 1, 2 to energize the reset coil N of the switch S which is stepped to its home position. At the end of a predetermined time interval greater than that required by the delay TD-5 to close its contacts 1, 2 the motor 51 completes one revolution of cams 52, 53 to restore the switches S22, S23 thereby de-energizing the motor 51 and establishing a circuit for lighting the ready lamp which lights on operation of the relay L after resetting of the remote selecting apparatus as described in Specification 826,383. Shortly after the time delay TD-5 has closed its contacts 1, 2, the motor 725 will have driven the cam member 786 to open the switch S26 which de-energizes the motor 752 and places the code disc 783 in circuit on the line 801. Specifications 741,622 and 826,805 also are referred to.