Patent GB-627082-A (GB)
Title: Improvements in or relating to electrical signalling systems
IPC: G08C13/02
Filed: 1947-02-06
Abstract: 627,082. Electric indicating systems. GUNNING, P. F. Feb. 6, 1947, No. 3617. [Class 40 (i)] In an arrangement in which a variable quantity is represented by a corresponding electric impulsing rate, and an indicator is operated in accordance with the number of impulses received in successive equal predetermined periods, accuracy is improved by causing the impulses, during the whole or preferably a later portion of each integrating period, to operate a storage device which subsequently transmits corresponding impulses at uniform speed to the indicator. As shown, contacts SMC are closed to operate a relay LG at a variable rate, corresponding, e.g. to the load on an electric generating plant. The integrating period is determined by contacts PA closed periodically at one minute intervals ; and further contacts PB closed periodically at one minute intervals but with a 30 second phase-shift relative to the operation of contacts PA, serve to control the length of the portion of each integrating period during which the storage device is operative. At the beginning of an integrating period with both contact PA, PB open and the equipment in the positions shown, the incoming line pulses over SMC operate relay LG which at contacts LG2 repeats the impulses over line P4 to the indicator, which may be as described in Specification 553,503. After half-a-minute, contacts PB close to energize a relay A which locks over its right-hand winding and energizes a thermostat type relay TH. After 20 seconds-its assumed delay time-relay TH operates, and energizes a relay C when LG is next normal. Relay C locks and at C2 transfers the pulsing circuit from the line P4 to the stepping magnet MM so that subsequent incoming pulses step the uniselector M1. Immediately M1 is stepped the short circuit across a relay FP is removed ; FP pulls up, and at FP2 energizes a relay U which energizes the stepping magnet SLM and a delayed release relay DEL which short-circuits relay U at DEL1. The uniselector SL2 thus steps by interaction of relays U and DEL until aligned with the marked contact in the switch bank M1, when relay FP is again short-circuited. The incoming pulses over contacts SMC each represent 4 units. The switch SL2 takes four steps for each step of M1 and at each step of SL2 the relay U sends a units pulse over line P1 to the indicator. The stepping speed of switch SL2 is constant and depends only on the delay of relay DEL which is determined by the shunting capacitor QA. At the end of the integrating period contacts PA close to extend positive over line ITP to the indicator to effect display of the new value. Relay B is also operated, and releases relays A and TH. Relay C also releases, provided that switch SL2 has caught up with switch M1 in which case all the equipment is again in the condition shown. If SL has not caught up with M1 relay FP1 is still operated and relay C remains locked at FP1 so that incoming pulses are diverted to the stepping magnet MM and as indicated above will be repeated to the indicator as four-unit pulses and produce the same effect as if transmitted direct. When relay FP finally releases, relay C also releases and the incoming pulses are repeated directly over line P4. The contacts DA, DB, DC are carried by relays in the indicator. For example, DA may be operated at # th full-scale reading, DA and DB at “ and all three relays at ¢ full-scale reading. In this way, when relay A is energized, i.e. during the final ten seconds of the integrating period, the capacitors QB . . . QD are connected in parallel with QA to adjust the stepping speed of SL in dependence on the indication given by the preceding integrating period. If, however, the incoming pulses are bunched at the end of the integrating period so that there is a carry-over into the next period, relay A is de-energized at the initiation of this next period and shunts the capacitors at A2 by resistor YC to ensure maximum stepping speed of SL.