| 摘要 |
PURPOSE:To enable highly accurate measurement, by alternately sampling input voltage proportional to voltage and input voltage proportional to a current by an A/D converter. CONSTITUTION:A current input terminal 1, a voltage input terminal 2, an analogue multiplexer 3 and an A/D converter 4 etc. are provided. The input of a voltage proportional signal is alternately sampled from the terminal 1 at every definite time to be stored in a memory 6 through CPU5. Thereafter, the voltage input signal taken in from the terminal 2 is regarded as a sinusoidal wave and subjected to numerical analysis to calculate the max. value thereof. By this method, the voltage of the current input signal inputted from the terminal 1 at a measuring point is interpolated from the sinusoidal wave curve calculated by numerical integration and calculated. The result obtained by multiplying two numerical values is again subjected to numerical integration to make it possible to measure electric power with high accuracy.
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