POWER MEASURING APPARATUS, POWER MEASURING SYSTEM, AND POWER MEASURING METHOD

A power measuring apparatus (112) is provided with: a line connector (112s) connected to a power source line (11), which supplies power to equipment; and a measuring circuit (1122), which measures a voltage and a current supplied to the equipment by means of the connected power source line (11). The power measuring apparatus (112) is also provided with: a calculator (1129) which calculates, on the basis of the measured voltage and current, power consumed by the equipment; and a transmission line connector (Pt) connected to a transmission line (21) that transmits data used for the purpose of monitoring the equipment. Furthermore, the power measuring apparatus (112) is also provided with a transmitter (1126) that transmits data indicating the calculated power to the transmission line (21). Consequently, the power measuring apparatus can be installed in equipment at lower cost than before.