Self-Integrating Rogowski Coil for High-Impulse Current Measurement

This paper presents the operating principle, the performance under impulse condition, and the design of a self-integrating Rogowski coil for measuring high-impulse currents. Oscillatory and overdamped unidirectional impulse currents are generated up to 10 kA and measured by different methods, namely, two commercial impulse current transformers, a resistive shunt, and the newly designed self-integrating Rogowski coil. For the resistive method, the voltage drop across the shunt affects the total voltage measured across the test object and causes distortion in the case of simultaneous measurement by an impulse current transformer having a small aperture. The Rogowski coil theory under impulse current conditions is presented. The concept of transmission lines is used, and the line parameters are optimized to achieve a self-integrating mode and avoid spurious effects of reflections and stray capacitances. The output voltage linearity of the designed self-integrating Rogowski coil is checked using different linear and nonlinear loads and coil termination resistances. It is found that at a termination resistance of 1 ¿, satisfactory impulse current waveforms are measured by taking the commercial impulse current transformer as a reference signal. Results reveal that the measurement errors for the current peak and front and tail times are ±2%, ¿6%, and ¿ 12%, respectively. Overdamped impulse currents are generated by different generator capacitances, where comparisons between the measured and calculated current waveform parameters have shown good agreement.