The source of the inductive current transformers metrological properties deterioration for transformation of distorted currents

• It is presented how CT metrological properties can be determined in non-sinusoidal conditions.
• It is discussed what is the connection between current error/phase displacement and composite error.
• CT magnetic circuit operation for sinusoidal and distorted supply voltage of the primary winding is analyzed.
• The results indicate that in condition of distorted current transformation metrological properties of CT are deteriorated.
• Moreover, conductive disturbance in CT primary current increase main harmonic current error and phase displacement.

The aim of the paper is to present results explaining the phenomena of the inductive current transformers (CTs) metrological properties deterioration for the transformation of the distorted currents. In the article the influence of the conductive disturbances on their accuracy of transformation of the distorted signal is described. Analysis of the results from the laboratory studies show, that conductive disturbances in the CT primary current, in some measuring conditions, cause increase of the current error/ratio correction factor and phase displacement/phase angle of transformation of the main harmonic of distorted current.