L. Furmankiewicz

Influence of the nonlinearity of measurement transformers on effectiveness of module error correction

The article presents the program spectral line method of module error correction in linear input circuits. The method requires the knowledge of the frequency characteristics of the module errors and the phase errors of the input circuit to be corrected. The method was used for frequency error correction of measurement transformers applied in electronic power transducers. Such input circuits are nonlinear and distort the measured signals. The article presents the analysis of the influence of the nonlinearity of the input circuits upon the effectiveness of correction of frequency errors of the input circuit module at measurements of the root-mean-square value.

The properties of the method of frequency errors correction of input circuits within the range of nonlinear operation

The paper concerns the method of the correction of frequency errors of input circuits, elaborated for correction of module errors and phase errors of linear input circuits. The method is implemented in the spectral domain in a programmed manner. The author presents the findings of experimental research which show the efficiency of the method in measurements of rms value of nonsinusoidal current within the range of linear and nonlinear processing characteristics of a current transformer.

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.