POWER SENSOR, SENSOR POWER VOLUME EXPANSION UNIT AND ELECTRICAL POWER MEASUREMENT SYSTEM

摘要

PURPOSE: A watt hour sensor, an expansion unit of a watt hour sensor, and a watt hour measurement system thereof are provided to increase the measurement accuracy of watt hour with simple construction. CONSTITUTION: A watt hour sensor (1) measures the current of a first measurement target part and the voltage of an alternating current (AC) circuit (5). A second watt hour sensor (2-4) measures the current of a second measurement target part. The watt hour sensor communicates with the second watt hour sensor. The watt hour sensor repeatedly outputs the synchronization pulse to the one point of the measurement period including the predetermined time width. The watt hour sensor individually transmits digital signals indicating the measured voltages. The watt hour sensor calculates the watt hour at the first measurement target part based on the measured voltage and current. The watt hour sensor calculates the watt hour based on voltage data indicated by the digital signal from the data of the measured current.