| 摘要 |
PROBLEM TO BE SOLVED: To provide an electric power measurement device capable of measuring electric power with high accuracy even in a situation where the electric power supplied via an electric power line fluctuates severely.SOLUTION: A current transformer 101 outputs an electric current in accordance with the electric current flowing in an electric power line 109. A switching element 102 switches the connection destination of the current transformer 101 to a charging circuit 107 or a measurement circuit 103 under control of an MCU 105. The measurement circuit 103 outputs a voltage corresponding to the output electric current of the current transformer 101. An A/D converter 104 A/D converts the output voltage of the measurement circuit 103. The MCU 105 executes an ordinary measurement or a reference measurement using the A/D converter synchronously with the measurement period. The MCU 105 controls the sampling period of A/D conversion in the ordinary measurement in accordance with the A/D conversion value. When the A/D conversion values of the reference measurement and ordinary measurement are close, the electric power obtained by the reference measurement is made the measured electric power in the ordinary measurement. |
