| 摘要 |
PURPOSE:To obtain accurate power consumption even in case of variation in power ratio between a voltage and current as to momentary, by subtracting negative- polarity-directional power from an integrating count value by providing a polarity decision circuit and polarity inverter circuit. CONSTITUTION:Signal polarity decision circuit 14 is provided to the output part of power detection circuit 11 and when a decision that momentary power P obtained by power detection circuit 11 is positive in polarity is made, change-over circuits 13a and 13b are changed over to supply it to frequency converter circuit 15 before counter 16 sums up and counts it. On the other hand, when a decision on a negative polarity is made, change-over circuits 13a and 13b are changed over to fixed terminal parts at the opposite sides. At this time, momentary power P of negative polarity inverter circuit 12 and outputted as positive power. This positive power P is supplied through frequency converter circuit 15 to the subtraction-side fixed terminal part of counter 16, where it is subtracted from the integrating count value. In this way, accurate power consumption can be found even in case of constant variation in power ratio between a voltage and current. |
