On-Line Phase Measurement of Power System Harmonics

A new instrument which allows on-line measurements of the phase angle of harmonics is presented. It is used in conjunction with a wave analyzer and provides amplitude and phase angle of harmonics. The principle of the measurement is an analogue null detection, hence the accuracy depends practically only on the quality of the tuned voltmeter used. Direct digital read out is provided for the angle. Design criteria, practical implementation and actual performance are presented. The instrument has demonstrated great potential in the study of ferromagnetic devices, core-loss curves, and power system harmonics.