A Method, and its Instrumentation, for Measurement of Small Differences of Vectorial Values

The paper considers a measurement method that determines small differences of vectorial values (less than 1% in magnitude and 0.02 rad in phase). The solution is based on the use of 2-channel digital instrument for non-coherent sampling of harmonic signal instant values. Method description includes analysis of methodic inaccuracies. The study demonstrates that common off-the-shelf power analyzer is made applicable, due to the method proposed, to onsite calibration of instrument transformers of commercial frequency current or voltage