Patent ID: 8476895

Claim:
A power measuring system comprising: a voltage sensor for detecting a voltage waveform of a power line in a noncontact manner through electrostatic coupling; a current sensor for detecting a current waveform of said power line in a noncontact manner through electromagnetic inductive coupling; a measuring apparatus including first communication means and a control portion which is connected to said voltage sensor and said current sensor; and a load terminal connected to said power line and including a load of a predetermined value, second communication means for communicating with said first communication means, and a measuring portion for measuring an effective value of a current flowing through said load and calculating an effective value of a voltage based on the measured effective value of the current, wherein the measuring portion of said load terminal transmits the effective value of said current and the effective value of said voltage to said measuring apparatus via said second communication means, the control portion of said measuring apparatus calculates a power value based on the effective value of said current and the effective value of said voltage, which have been received from said load terminal via said first communication means, as well as on the voltage waveform acquired from said voltage sensor and the current waveform acquired from said current sensor, said measuring apparatus includes storage means, upon receiving the effective value of said current and the effective value of said voltage from said load terminal in an initial stage of installation, the control portion of said measuring apparatus calculates a first power value based on the effective value of said current and the effective value of said voltage, calculates a second power value based on the current waveform acquired from said current sensor and the voltage waveform acquired from said voltage sensor, calculates a correction coefficient based on said first power value and said second power value, and stores the calculated correction coefficient in said storage means, and during power measurement, the control portion of said measuring apparatus calculates a power value consumed regarding said power line based on the current waveform acquired from said current sensor, the voltage waveform acquired from said voltage sensor, and the correction coefficient stored in said storage means.