Patent GB-371026-A (GB)
Title: Improvements in or relating to systems for repeating meter readings electrically
IPC: G08C15/12
Filed: 1931-01-13
Abstract: 371,026. Electric signalling systems. SIEMENS & HALSKE AKT.-GES., Siemensstadt, Berlin. Jan. 13, 1931, No. 1202. Convention date, Jan. 18, 1930. [Class 40 (i).] In a system for indicating periodically the totals of a counting meter or the summation of the totals of a plurality of meters, combinations of impulses characteristic of the meter totals are transmitted through the intermediary of synchronously driven switches to operate corresponding combinations of relays which control the amount of resistances connected in the circuit of indicating instruments. The resistances may comprise an arm of a Wheatstone bridge which is adapted for automatic balancing and the control of a recording apparatus. As shown in Fig. 1, meters 1, 2 control gears 3, 4 which are adapted to prepare different combinations of circuits 5 according to the number of revolutions made by the meters. The various contacts 5 represent different numbers of revolutions related according to a geometrical progression, e.g. 1 :2: 4 : 8 &c., the contacts being energized in different combinations as the number of revolutions of the meter progressively increases. The readings of a meter are repeated periodically by the operation of synchronously operated distributors 7, 12, relays 14 .. 17 being operated in a combination according to the meter reading at the moment. The relays control the short-circuiting contacts of pairs of resistances of equal value the arrangement being such that upon operation of a relay one resistance is switched out while the other is switched in to maintain the total resistance constant. A cross-coiled instrument 23 is connected across one set of resistances in order to indicate a value corresponding to the particular combination of relays selected. Similar arrangements are employed for repeating the readings of the meter 2 on instrument 24. An instrument 25 is connected across both sets of resistances and thus indicates the total of the readings of meters 1, 2. The relays 14 .. 21 are adapted when operated to remain locked in circuits not shown. Means may be provided at the receiving station to indicate whether the indications are received at the correct periodicity. A time supervising device, e.g. clockwork or a bimetallic relay which is heated upon each signal transmitted, is adapted to operate an indicator in the event that the interval between two successive signals exceeds a predetermined amount. Alternatively the time supervising device may open the locking circuits of the relays such as 14 .. 17. The resistances are proportioned in the ratio 1:2:4:8 &c. corresponding to the code used at the transmitter. In the arrangement shown in Fig. 1 after the meters 1, 2 have reached their maximum readings, signalling continues again from the minimum values. Fig. 2 shows a receiving arrangement adapted to total and continuously register the readings of several meters. Relays 140 .. 250 comprise three sets of receiving relays operated in a manner similar to that previously described. The corresponding resistances form an arm of a Wheatstone bridge, the other arms of which comprise resistances 40, 41, 42 the latter being automatically regulated by a motor 49 to maintain balance. When the value of the relay controlled resistances increases in accordance with increases in meter readings, the bridge is unbalanced and bridge relay 44 is operated to close, at contact 50, the circuit of motor 49 which operates the contact 45 to the left to restore balance. When the contact 45 reaches the limit of travel contacts 57, 58 are operated and switch 66 is stepped to switch in a resistance 72. This causes operation of relay 44 into contact with contact 73 and the motor is operated in the reverse direction to restore the contact 45 to its initial position in which the bridge is balanced. Further increase in meter reading causes similar operations, the resistances 72, 74, 75 being switched in turn into the variable arm of the bridge. The motor also controls through a one-way clutch 79 counting and recording mechanism, the travelling strip 52 of the latter co-operating with a pen oscillated by linkwork 54, 55. Fig. 3 shows apparatus whereby the ratchet mechanism controlling the switching in of resistances 72, 74, &c. may be stepped back in the event that the meters again revert to the transmission of minimum values after passing through the maximum value. Since upon reversion the resistance in the bridge circuit is lessened armature 490 of relay 44 closes at contacts 760 the circuit of relay 761 which effects operation of the stepping back magnet 767, opens the circuit for reverse driving of the motor 49 and operates relay 764 which effects release of relay 761. Thus resistances such as 75, 74, &c. are switched out in order to restore balance. In order to prevent operation of the setting back mechanism during normal operation of the system for increasing values of resistance, relay 780 is operated to open the circuit of relay 761 when the switch arm 69 bridges additional contacts such as 710, 720 during the process of switching in the extra resistances. The Specification as open to inspection under Sect. 91 (3) (a) states that indications may be transmitted when desired instead of periodically. This subject-matter does not appear in the Specification as accepted.