JPS5450369A - Watt meter - Google Patents

Abstract

PURPOSE: To produce a watt meter, which is high in accuracy and stability, by providing a mirror integrating circuit which is operative to render a switch circuit conductive during a half period in response to detected signals so that the signals proportional to the current consumption may be integrated.

CONSTITUTION: If there appears a negative half wave of AC voltage signals e_v at the output terminal of a voltage transformer 11, those signals e_v are averaged into an inversely proportional voltage, which is then fed to the input terminal of a miror integrating circuit 18. In this instance, the mirror integrating circuit accomplish the reverse integrating operation to vary it in the positive direction because it is supplied with the negative voltage signals from an inversely proportional circuit 15. And, the pulse width T₂ for the one period T at the output of the mirror integrating circuit 18 is made proportional to the power consumption considering the power- factor. Since, in this term T₂, the "1" signals are generated from an AND gate circuit 17, the clock pulses CP are generated from an ANd circuit 20 and are counted and integrated by a display counter 21 so that they may be obtained as the watt value

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