Three-phase power meter and three-phase kilowatt-hour meter are commonly used in substations to measure the power and energy.Because the above two kinds of meters are usually connected through several secondary devices to PTs and CTs

as well as maintenance staff often do（relay protection

high-voltage test

measuring instrument

electric energy measurement）cycle test of the work

wrong connection possibly cause errors of three-phase power measurement and three-phase kilowatt-hour measurement.Herein the article analyses a quick（3 min）and practical method of the judgment and exclusion the wrong connection based on the Electrical Hexagonal Phasor Diagram and using of Digital Bi-clamp Phase Meter.