| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a measurement apparatus for enabling a current measurement at the high current waveform accuracy, and enabling an effective power measurement for considering a current waveform. Ž<P>SOLUTION: A current is detected by a current sensor 1, converted into a digital signal by an A/D converter 2, and loaded to a data acquisition register 3 by a sample signal from a sample signal generating circuit 7. The data loaded to the register 3 is loaded to a microprocessor 4, and processed. A V-cross timing detecting circuit 5 inputs AC power, and detects timing when the AC power crosses reference voltage. An oscillator 6 generates a frequency whose step-down value does not have a conjugate number relative a frequency of the AC power or which is a prime frequency or a prime multiple frequency. The sample signal generating circuit 7 transmits a zero-cross timing signal for indicating a change from a negative voltage to a positive voltage in the sample signal. The microprocessor 4 calculates a high-accuracy effective current, and calculates correct effective power and a power factor by utilizing a relationship between the sample number and a phase angle. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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