Effective control of the error in a direct measurement of core-loss power

Accuracy of a direct measurement of core-loss power is severely limited in many applications by the extra phase shift between the measured voltage and current. An analysis of the error is for the first time performed, which not only unfolds the hidden physical nature behind it, but also reveals a simple and effective method to control the sensitivity and hence the error. This method can also be used to satisfy a prescribed tolerance. Extensive measurements on a TDK PC40 core yield results which support the analysis.