Patent GB-315220-A (GB)
Title: Improvements relating to the electrical control of apparatus such as railway points and signals from distant points
IPC: B61L7/08
Filed: 1929-07-06
Abstract: 315,220. Westinghouse Brake & Saxby Signal Co., Ltd., (Assignees of Lewis, L. V.). July 9, 1928, [Convention date]. Selective distant control and tell-tale systems. -For the electric control of selected devices at one station selected out of a number of stations and for indicating in a central office the condition and position of all the apparatus at the distant stations by means of a single pair of line wires from the central office to all the other stations, the central office is fitted with a panel relative to each distant station and a common set of relays, some of which are slow-release relays having different delay intervals, by means of which a code signal comprising two groups of impulses of two kinds, such as short and long intervals of break between short intervals of current, is transmitted to the line wires, each station having a similar set of relays for decoding the received signals and for sending a similar indication-code to the central office. The first group selects a particular station and the second group effects, when the code is completed, the operation of the points and signals required to be set. The common set of relays are used also for reception of the code for control of the indications at the office. If the line circuit is either closed or opened for an interval in excess of that used in a code transmission, the whole of the apparatus is restored to normal condition. Provision is made for the simultaneous preparation for code transmission to several stations, but codes cannot be transmitted simultaneously between the office and two stations nor to and from the office and any station. If an attempt is made to transmit simultaneously from the office and a station, the office takes precedence and if two stations attempt simultaneous transmissions, the one nearer to the office takes precedence, the other station transmitting its code as soon as the first transmission is completed. Sparking at contacts, at which circuits are broken while current is flowing, is avoided by the provision of rectifier contacts which offer high resistance to normal currents but low resistance to discharge currents of the relays in the opened circuit. These rectifiers also render the relays slow-releasing but do not prolong the pick-up time. Figs. 1 and 2 show the coding apparatus at the office with one panel, enclosed in chain-lines, carrying switch 1d, 1f , for controlling, and lamps 127, 128, 129, 131, 132, 177 for indicating the condition of, the devices at station 1, shown on Figs. 3 and 4, which comprises points 3 and signals ILA, ILB, IRA, IRB, relating to traffic in two directions over the main and branch lines. The code current adopted for this system consists of sixteen interruptions of long or short duration of the current from battery N over the line wires D<1>, D<2> in which relays OR, IR are included. The coding and decoding apparatus at the office includes a series of counting relays OB1, OB1a - - OB8, OB8a which are energized successively and other counting relays 001, OC1a, OC2 which enable, the repeated use of the first series. The long and short impulses are determined by relays OJ with a release delay of say 0.2 secs., and timing relays OX, OY, OZ the sum of the pick up and release of which is say 0.1 sec., a master relay OT with a release delay of 0.1 sec., and a quick acting transmitting relay OV. A similar set of relays is installed at each station. To transmit a code signal, the press contact OP1 is momentarily closed, and relay OH1 picks up and holds its armatures, and polarized starting relay OH at the coding apparatus is energized over contact 50, and closes contact 51 by which the circuit to the master relay OT is closed over armatures 32 of relay OKa and 52 of relay OK. The relay is maintained until the transmission is ended so that the line circuit is open unless the transmitting relay OV is energized. Relay OR drops armature 25 and closes successively pick-up circuits for relays OB1, OC1, OK, OKa, OE, which are all held by maintaining circuits. With relay OT energized, relay OX picks up, then relays OY, OX, OZ in succession. Relay OJ opens 0.2 secs. after relay OR and opens the stick circuit to relay OZ which opens contact 68 and causes relay OX to open contacts 63 and energize relay OV to close the line circuit 0.4 secs. after relay OR was de-energized, and energizes relay OR and causes relay OB1a to pick up. Relay OY drops armature 69 after 0.1 sec. and relay OV opens the line circuit again and OR is de-energized, and causes counting relay OB2 to pick up. Thus the first impulse of the code is a 'long one. On the de-energization of relay OY, relay OX picks up and is held by a stick circuit, and causes OY to pick up again. Circuits are closed to relays OG1, OL1, and armatures of these relays de-energize relays OE and OX and so cause relay OV to remake the line circuit after an interval due to the sum of slow pick up and release of the various relays, thus producing a second long impulse. Relay OR again picks up and energizes counting relay OB2. The de-energization of relay OX to end the second impulse causes relay OY to drop armature 62 after 0.1 sec., so that relay OX again picks up and energizes relay OY, but no holding circuit exists for relay OX because relay OE is de-energized. Thus relay OV is energized to reclose the line circuit after a short impulse and relay OB3a is picked up. This pumping action of relays OX, OY is used to produce all short impulses in the code. Long impulses are produced when a holding circuit is formed for relay OX, over the contact of the counting relay OB in operation at the time and a contact on the panel related to the station to be selected or to the lever controlling the operation to be performed at that station, such as the contact 80 of relay OH1 for selection of station 1 or contact 1d controlling the points at that station. The second to the eighth impulses cause the selection of the required station. After the eighth impulse, relay OC2 is substituted for relay OC1 and the counting relays function in order for the last eight impulses in the code, which select the apparatus to be operated. At the end of the last impulse, which is always a long one and serves to put in operation the circuits prepared by the earlier impulses, the relay OR remains energized and, after an interval, relays OKa and OK drop their contacts and make ready the pick-up circuit for the master relay OT. At station 1 the line relay IR responds to each make and break and, at the first impulse, closes a pick-up circuit to relays IBI, IC1, IK, IKa, and these are all held by stick circuits. Relay IJ drops its armatures 0.2 seconds after contact 90 opens. This relay therefore opens at a long impulse but not at a short one. At long impulses in the first half of the code a circuit is made over a contact of relav IJ, the contact of the counting relays in use, and jumpers 101, 106 which are placed in conjunction with the counting relays in accordance with the code for the station, to energize at successive long impulses the relays IE, IG, IS, at the selected station. At the end of the eighth impulse, relay IC2 is substituted for relay IC1, and in the second half of the code circuits are made over contacts 111 of relay IS and the counting relays to selected register relays IF3 - - IF7. At the last impulse a circuit is made over contact 114 of relay IBS and the contacts of the register relays to the relays IWS, IHS, IFS which control the points and signals at the station 1. In conjunction with track relay ITR and contacts 10, 10<a> which are closed only when all signals are at danger, the relay IWS controls the relays 1h, 1k for the reversible motor IM which operates the points 3. The signal operating devices are controlled by relays ILAH, IRAH, ILBH and IRBH which are controlled by relays IHS, IF'S in conjunction with contacts 16, 19, 21 operated by the points. Lamps on the station panel in the office are lighted to show the position of the points and signals and the presence of a train on the track section by the transmission of a similar code over the same line wires, the coding current transmitting apparatus being put in operation by energization of the starting relay IH by either de-energization of track relay ITR or by contact 165 moved by the points or by contacts on the signal relays. The code is transmitted in a manner similar to the transmission from the office, the master relay IT being energized during the whole transmission and the circuit to relay IR being completed by the contact 153 of relay IV through the impedance 154. All stations beyond the transmitting station are cut off by the open contact 152 of relay IT.. The code transmitted is decoded by means similar to that at the stations to energize the relays OS1 &c. of the appropriate panel by the second to eighth impulses and the register relays OF1 - - OF7 by the ninth to fifteenth impulses. At the sixteenth impulse, a circuit is completed over the contacts of the selected relays to the lamp relays ITK, IWK, OHKI, CWDI, OFKI, OFDI, controlling respectively lumps showing occupation of the track by a train, the position of the points, and the state of the signals. The operator in the office may, at any time, test the position of the apparatus at ary station by closing the checking key and the push contact for the desired station. The station by closing the checking key and the tion code according to the position of levers 1d, 1f on the station panel are then transmitted but the ninth impulse is a long one and causes starting relay IH at the station to start the transmission of a return indication as soon as the outward code is completed.