Influencing Factors and Error Analysis of Pulse Current Measurement With Air-Core Rogowski Coil

Rogowski coils for fast pulse current measurement need sparse winding. However, sparse winding might make the coil distribution uneven and result in measurement error as the measured conductor is placed eccentrically or obliquely or if there is nearby current external to the coil. In this article, the induced electromotive force and the resulting measurement error are determined for nonuniform turn density along the bobbin. The interturn capacitance is related to the time response and is an important parameter, but its accurate calculation is difficult. A data-fitting method based on finite-element simulation modeling is proposed, and the interturn capacitance is calculated. The displacement current flowing through the gap of a shielding container would also introduce measurement error for high frequency. The error caused by the displacement current is derived, and the influencing factors are discussed.