Patent GB-243020-A (GB)
Title: Improvements in or relating to electric signalling or controlling systems
IPC: H02J13/00
Filed: 1925-11-14
Abstract: 243,020. Metropolitan-Vickers Electrical Co., Ltd., (Assignees of White, T. U., and Gardner, J. E.). Nov. 15, 1924, [Convention date]. Selective distant control systems and apparatus. -Relates to a system for the distant and supervisory control of electric power substation apparatus of the kind in which the apparatus at the substation and the supervisory signals and control keys at the control office are associated with chains of relays which are operated synchronously in sequence. The units may be operated at the substation or automatically according to the load. Figs. 1 to 4 show the central station, and Figs. 5 to 8 show the apparatus at the substation. The central station is provided with a key K for each apparatus unit, such as a circuit breaker C, Fig. 8, at the substation. The apparatus units and their corresponding keys are associated with the groups of selecting relays 500 - - 509, 300 - - 309 respectively which are energized and de-energized in succession under the control of the groups of counting relays 700 - - 723, 100 - - 123 operated in sequence by pairs of line relays 618, 412 or 615, 415 at the stations. These pairs of line relays are connected alternately to the line 470. Normally, a relay 209, Fig. 2, is energized in series with a. relay 816 over the control line 470, but operation of a "start " key K<1> opens this circuit and connects the line 470 to the control relays which operate the counting and selecting relays in sequence. When it is desired to close a breaker at the substation, the corresponding key K at the control office is operated to replace an earth connection on a contact of the corresponding. selecting relays, which causes the normal operation of the control circuit, by a battery connection so that when this relay is operated, together with the corresponding relay at the substation, a circuit is closed over the line 18 to operate the .circuit breaker.' When the circuit breaker is operated a circuit is closed over the line 17, through the same selecting relays, to operate the corresponding supervisory signals, such as the lamps 262, 263. The supervisory signalling operation also completes circuits through the selecting relays for restarting the operation of the control circuit and the remaining relays in the groups. A lamp is associated with each selecting relay at the control station for the purpose of informing the operator of the position of the selecting mechanism at any moment. The operations of the control circuit counting and selecting relays are the same as those described in Specification 234,111. The invention is characterized by (1) means operative upon failure of any one of the selecting relays to be restored to normal after operation, to prevent the sequential operation of one or both groups of relays, (2) means for restoring one or both groups to normal in the event that the relays fail to operate synchronously, (3) a signalling device adapted to be operated at each operation of one of the line relays at the control office, and (4) a Wheatstone bridge testing circuit for testing faults upon the line wires 17, 18. (1) If, due to mechanical defects, the selecting relays do not restore to normal promptly upon their respective circuits being opened, relays 406, 407 at the control office and 602, 603 at the substation are operated to prevent further operation of the control circuit. During the normal operation of the system, relays 420, 610 connect and disconnect the line 470 to the control relays simultaneously with the energization and deenergization of the selecting relays. The energization of the relays 410, 610 is controlled by pairs of relays 406, 407, and 602, 603, which are associated with alternate selecting relays at each station. De-energization of the relays 420, 610 to connect the line 470 to the control relays is effected by pairs of relays 408, 409 and 600, 601 which are also connected to alternate selecting relays. Normally, when the contacts of a. selecting relay, e.g. at the control office, are closed one or other of the relays 408, 409 is energized to open the circuit of the relay 420 and complete the control circuit. When the contacts are opened, one or other of the relays 406, 407 retracts its armature to energize the relay 420 and open the control circuit. The relay 610 at the substation is controlled in a similar manner by the relays 600 - - 603. If, however, a relay such as the relay 309 remains operated, through a mechanical defect, after its circuit is opened and the next relay 308 is operated, both relays 406, 407 are operated and the circuit of the relay 430 is held open to maintain the line 470 in connection with the same control relay. In consequence of this the control operation is stopped. The relay 610 at the substation is operated in.a similar manner if a selecting relay does not restore to normal before the operation of a succeeding relay in the chain. When the relay 407 is operated, a relay 400 is energized to operate a relay 411 and a buzzer 410. Thus if faulty operation occurs in the selecting group at the control office, the operation of the buzzer 410 is maintained to give a warning. (2) When the relays 420, 610 are energized the line 470 is connected to the relays 418, 612. These relays each have a battery and earth connection which are alternately connected thereto by the operation of relays 413, 414, 416, 417 at the control office and relays 613, 614, 616, 617 at the substation. When the selecting relays at the two stations are working synchronously the battery and earth connections of these relays are made simultaneously so that no operation takes place. When, however, synchronism nolonger occurs, the relays 418, 612 are energized to operate slow acting relays 124, 725 which release the operated counting and selecting relays at both stations. (3) During the normal operation of the system the relay 411 is alternately energized and deenergized to alternately connect the control relays 412, 415 to the line 470. The buzzer 410 is thus operated at each operation of the control relay 412. (4) The line wires 17, 18 are normally connected to the fourth arm of Wheatstone bridge testing circuit, the other arms of which comprise resistances 239, 240, 241. A relay 211 is connected across the bridge and a relay 804 at the substation is normally in circuit with the line wires. When a fault occurs on the lines, the bridge is unbalanced and the relay 211 operates a buzzer 210 and a lamp. The relay 804 is also de-energized to operate a buzzer 801 at the substation. Specification 225,542 is referred to.