ELECTRICAL METERS

摘要

1,231,101. Electric calculators; meters. ENGLISH ELECTRIC CO. Ltd. 21 Feb., 1969 [21 Feb., 1968], No. 8411/68. Heading G4A. A digital circuit continuously calculates KVA demand (Z) from pulsed KWH and KVArH inputs (R and W) from the relationship shown in the curve of Fig. 3. Pulse inputs sets bi-stable T1 or T2 which are scanned alternately by bi-stable S1, any stored pulse setting a monostable Z1 to produce a +ve pulse A, while a voltage is produced at S1 which is 0 or +ve depending on whether the detected pulse is at R or W. A timer X1 produces phase-opposed square waves X 1 , X1 1 of eight times the frequency of Z 1 and S 1 . The pulses Z 1 are applied to a register B1-4 counting up to 16. Pulses Z 1 , X 1 , X1 1 , S 1 are applied in combinations to gates 15-18 to produce bunches of 8 pulses each. Gates 16-18 produce interleaved sets of 8 pulses each time the store W operates, to feed a reversible register A1-6 which counts forward as far as 64 and is then reversed by bistable A7 until it reaches zero again, corresponding to the left and right halves of the curve in Fig. 3. Register A1-6 resets when register B1-4 reaches full capacity. A logic system 35 produces an output which is fed to AND gates 36, 37 together with forward or reverse control from bi-stable A7 and the outputs from gates 16-18. OR gate 30 and EXCLUSIVE OR gate 25 combine to give a true or false output representing electronic subtraction of Z from 128, an inhibit input from 33 ensuring zero output between pulses. The resultant pulses feed a stepping motor 27 to drive a KVA demand indicator 28.