Patent GB-419401-A (GB)
Title: Improvements in and relating to systems for the communication of control and/or signal influences, more particularly for centralised traffic controlling installations
IPC: B61L7/08
Filed: 1933-09-27
Abstract: 419,401. Distant - control systems. GENERAL RAILWAY SIGNAL CO., Rochester, New York, U.S.A.-(Assignees of Judge, T. J.; 273, West Avenue, Rochester, New York, U.S.A.) Sept. 27, 1933, No. 26615. Convention date, Sept. 27, 1932. [Class 40 (i).] In a system for supervising and controlling apparatus at a plurality of substations, more particularly for a centralised traffic controlling installation, the central office and the stations are connected by a single line circuit and selection of a station is effected by impulses coded in respect of one distinctive characteristic, e.g. polarity, and signalling back from the substations is effected by impulses coded in respect of another characteristic, e.g. time interval between the impulses. The coding of the impulses in this manner facilitates duplex signalling. Fig. 1 shows the equipment at the control office and Fig. 2 the apparatus at one of the substations. As shown the apparatus at the substation is arranged to control the switches and signals of a railway section. The control office and substations are connected by a pair of line wires, the line relays at the various stations being connected in series. The selection of any particular substation and the control of apparatus thereat is effected by transmitting a characteristic series of positive and negative impulses whilst indications of the operation of substation apparatus are transmitted back to the control office by utilizing the spaces between the impulses and effecting characteristic timing of the spaces to produce long and short signals. In this manner duplex signalling may be effected over a common line circuit. Normal condition of equipment. Normally the line circuit is closed and all line relays are operated to the left (-ve). Operation of the line relays causes operation of relays J, JP in the office and relays J<1> in the substations. Each substation has a CD relay in the office, each CD relay being adapted to apply marking potentials to the contacts of a relay chain IV-4V. so as to determine the nature of the code to be transmitted. Control of substation apparatus. The relay CD corresponding to the substation to be selected is operated by a key SB. Relay CD operates relay C which operates PL to open the line circuit and release relays F, F<1>, F<2> . . . . . Release of F in the control station brings about operation of relays SA, SAP which operate relay CS in a circuit from +ve over contact 25 of relay CD, the relay CS reversing the battery connections to the line wires. Relays J, JP release and effect release of C, PL and again close the line circuit. Relays F, F<1> &c. again pull up and an impulse of reverse polarity is transmitted to condition relays SOS at the substations. Control station relays J, JP, E, PL are again operated to open the line circuit and thereby terminate the preliminary impulse which is used for operating relays SOS. Upon release of the line relays, the first relays 1V, 1V<1> of the chains in the stations are operated the relay 1V effecting release of relays E, PL and again closing the line circuit. The relay CS remains energized over marking jumper 55 and contact of relay 1V to ensure that the next transmitted impulse is of +ve character. Line relays are again operated. The substation relay SOS is released upon operation of chain relay 1V<1> but when the line relay F<1> is again operated, SOS is again operated over contacts of 1V<1> and jumper 138. This stepping operation of the relay chains 1V-4V, 1V<1>-4V<1> is continued, positive impulses being transmitted when the chain relays pick up battery marking and negative impulses when marking is absent and relay CS is allowed to relapse. At the substations, the relays SOS are jumpered by connections, such as 138, 145, 149, so that at the end of " station selection " impulsing only one SO relay (energized in series with SOS) corresponding to the selected station remains energized. Further impulses are then transmitted in accordance with the setting of control levers, such as SML, to effect operation of apparatus relays, such as SMR, over the back contacts of corresponding relays. At the end of impulsing, the line circuit is again closed and relays F, F<1> operated. After a short interval relays SA, SAP, SA<1>, SAP<1> at the stations are released to unlock the stepping relays. Transmission of indications from a substation. A change in the condition of a control or signalling device at a station brings about the release of relay CH. The indication code of each substation is determined by the jumpers 171, 172, 173, 187, 191, 192 which are arranged to determine the timing of the pauses between impulses so that a station code is made up of long and short inter-impulse pauses. When CH relapses, relay PL<1> at the incoming station is operated to operate the station relay SI and open the normally closed line circuit to cause release of the line relays F, F<1> and initiate a cycle of operations of the relay chains in a manner similar to that already described. In this manner SA, SAP, SA<1>,SAP<1> at the stations are operated and J, JP, J<1> are released but relays CD, CS remain inoperative since no control operation has been initiated. Since relay CS remains down all the impulses transmitted between the stations are of a -ve character. When relay J<1> releases, PL<1> releases and relay SI is locked up over back contacts of the chain relays and the " long " bus 174. When finally J, JP release central office relay PL is released and the line circuit is again closed. Upon operation of the line relays, PL, PL<1> are again actuated to open the line and initiate the first " indication " pause period. Relays 1V, 1V<1> are pulled up in a manner similar to that previously described, the relay PL, is released to pick up relay C, the line circuit continuing open due to the continued operation of relays PL<1>, FP<1>. Relay C again operates PL, EB. When relays J, JP release the line circuit is closed, the relay J<1> having released during the release time of J, JP to release PL<1> and prepare the line circuit at that point. The relay SI remains locked up over contact 178 of IV<1> and jumper 171 the latter being effective to make the period long. At stations where the jumper is omitted, the SI relays drop out. When the line relays are again energized relays J, JP, J<1> are energized and these relays remain operated throughout the cycle until another long pause as determined by the marking is required. Following operation of the line relays, relay PL<1> is however not operated owing to the absence of a jumper at 191 so that when PL releases at the central office in response to release of the line relays the line is immediately reclosed thus ensuring that the interimpulse pause is "short." Chain relays 2V, 2V<1> are operated and at the stations provided with jumper 172 relays SI are maintained operated. The provision of jumper 192 ensures that the third pause between impulses is a long one. Similar operations are continued, the character of the pauses being determined by operation or non- operation of PL<1> according to the markings provided by jumpers 187, 191 . . . . After a " station " code is transmitted, further indications as determined by the condition of indicat:on relays such as A<1> may be transmitted. At the central office, the pauses between the impulses effect the selection of a relay, such as ST, individual to the sending station over the contacts of relays PT<1>, PT<2>, PT<3> which are energized in characteristic combinations. These relays are operated by a relay K which is only pulled up when JP releases in response to a long pause between impulses. The further impulse pauses indicative of the condition of apparatus at the sending station are effective to operate indication relays, such as IN, over the contacts of relay ST. Preventing interference between incoming stations. When several stations cut into the line simultaneously, the SI relays of the stations are dropped in turn during the cycle of operations until only that station having a superior code is left in connection with the line. Duplex operation. Since the transmission of controls and indications take place during separate and distinct conditions of the line these transmissions are independent of each other and may be incorporated in the same operating cycle. Hence a control signal from the central office and an indication from a station may be transmitted simultaneously. Checking. The operation of the system may be checked by operating an SB button and transmitting a code to select a station. At the end of the cycle, relay IR at the station is operated to operate thermal relay TRP which after an interval causes release of CH which initiates a further cycle of operations which effects the display of indications in the central office corresponding to the apparatus at the station. Systems wherein each substation is provided with groups of apparatus equipments, Fig. 3. The Figure shows two groups of equipments, each group having LC, CH relays. These relays control the marking of common leads to the back contact of a common relay chain IV<1> ... 4V The relays LC', LC' are the interlocking control relays and are for the purpose of permitting only one group at a station to be operative at a time. Specification 377,971 is referred to.