Improvement the efficiency of frequency errors correction of current transformer within the range of non-linear operation

The paper concerns the method of the correction of dynamic magnitude and phase errors of input stages, elaborated for linear input stages and tested for measurement current transformers. The method is implemented in the spectral domain in a programmed manner using the FFT algorithm. Correction of signal spectrum is based on frequency characteristics of magnitude and phase errors of input stages, which are determined on the basis of previous measurements. The method may be used for measuring RMS value and power of signals. It is possible to apply the correction method in the non-linear operation of the input stage, however, the correction efficiency may then be reduced. In order to improve the correction efficiency within the range of non-linear operation of the input stage, frequency errors of the a current transformer were identified with poly-harmonic signals. This paper presents the findings of the research of correction of frequency errors of a current transformer with poly-harmonic signals in measurements of the RMS current and power. The applied identification method brought improved efficiency of the correction within the range of non-linear operation of the current transformer.