Patent GB-375349-A (GB)
Title: Improvements in or relating to electric signalling or selective systems
IPC: H04M11/00
Filed: 1931-03-18
Abstract: 375,349. Electric signalling and distant control systems. STANDARD TELEPHONES & CABLES, Ltd., FLINT, J. G., SKILLMAN, T. S., and GROVE, S. H., Columbia House, Aldwych, London, March 18, 1931, No. 8304. [Class 40 (i).] In a control system, selection of any particular apparatus or signalling unit or the transmission of a meter reading is effected by the transmission of a characteristic impulse code, the impulses of which comprise different combinations of a plurality of currents of different frequencies. Figs. 1, 2, and 3 show the transmitting and receiving equipment at the control station, the line wires a, b being normally connected to the receiving equipment as shown but being switched over by relay X to the transmitting equipment when the latter is taken into use. Transmitting apparatus. As shown, the control station is adapted to transmit outgoing signals constituted by two impulses each comprising different combinations of currents of different frequencies derived from the leads W.. Z. When a signal is to be sent lead 19 and a characteristic contact in each of the contact groups D11 .. D17, D21 .. D27 are earthed. Start relay SS is operated over lead 18 and sequence switch P is operated through one revolution to connect contacts D11 .. D17 to relays CS1 .. CS7 during the initial movement and the contacts D21 .. D27 to the relays during the final movements. Two impulses are then transmitted during the operation of the sequence switch the combination frequencies of the impulses being controlled by the energized relays in the group CS1 .. CS7 as determined by the markings in the groups of contacts D11 .. D17, D21 .. D27. Similar transmitting apparatus is employed at the substation but is modified to facilitate the transmission of three impulses in order to increase the scope of possible selection. Receiving equipment. The decoding apparatus of the receiving equipment is shown in Fig. 1, and comprises relays A .. D each tuned to one of the signalling frequencies and adapted to operate a corresponding relay in the group E .. H. The front and back contacts of relays E .. H are connected to normally-operated multi-winding relays K .. Q in such a manner that one relay only is released to operate a corresponding relay in the group AK .. AQ, for each impulse of different frequency combination. The relays AK .. AQ control leads 1 .. 7 connected to groups of selecting relays F1 .. F7, S1A, S8, &c., T1A, T50, &c. The first incoming impulse operates a relay in the group F1 .. F7 in series with relay MO, Fig. 3, which operates relays RR, C1, the relay C1 locking in series with relay CR1, which pulls up upon cessation of the impulse. Relay CR1 connects relay MO in series with a group of relays such as S8 .. S14 over the contact of the selected relay in the group F1 .. F7, and the second incoming impulse selects a relay in the group S8 .. S14 which is energized in series with relay MO. Relay MO operates C2 which functions in a manner similar to C1 to connect relay MO in series with the group, e.g. T50 .. T55 selected by the operated relay in group S8 .. S14. The third impulse energizes the selected relay and the relay MO is again operated to energize C3 which effects operation of relay FR which causes release of the selected relays in the groups F, S. The relays in the groups T50 .. T55 &c. are arranged in pairs, the first relay of each pair controlling a pair of signalling lamps and the second relay which is energized in parallel controlling a lamp which signals a change of indication. The first relay is self-locking and is de-energized by energization of an independent winding in response to a definite signal. The second relay operates upon either energization or de-energization of the first relay and locks up over a release key. Meter readings. When it is desired to obtain a particular meter reading, the appropriate key at the control station is operated to transmit a signal to the substation to initiate the meter reading and connect up the appropriate apparatus at the control station. Relay F1 in the group F1 .. F7 is individual to meter readings so that the first impulse of a signal characteristic of a meter reading operates relay F1. The meters M1, M2 at the control station are associated with groups of resistances, a particular resistance in a group being selected by groups of relays, e.g. S1A .. S7A, T1A .. T7A and connected in series with the associated meter in order to produce an indication characteristic of the reading of the distant meter. Upon operation of relay F1 in response to the first impulse of the meter code, battery is connected to the group, say S1A .. S7A, over terminals 10 11 which are short-circuited in response to the operation of the meter selecting key. The second impulse selects and operates a relay in the group to select a group of resistances associated with the meter and the third impulse operates a relay in the group T1A .. T7A to connect one of the resistances in the selected group in series with the meter and thereby produce an indication characteristic of the meter code. The Provisional Specification states that the system may be employed for the control of a plurality of substations over a common line and that telephonic communication may be established between the stations; moveover the positions of multi-position tapchange switches may be signalled and facilities may be provided for storing tap-change signals during speech or signals relating to circuitbreakers.