Multi-layer self-integrating Rogowski coils for high pulsed current measurement

Abstract

This paper presents design and calibration of a self-integrating Rogowski coil to measure high impulse currents. This coil is wound in single-, double-, and triple-layers by a coaxial cable without its polyvinyl chloride (PVC) jacket “sheath.” Overdamped unidirectional and oscillatory impulse currents are generated up to 7 kA and measured by different methods, namely, a commercial impulse current transformer (ICT), a commercial Rogowski coil (CRC) and the newly designed self-integrating Rogowski coil. The output voltage linearity of the designed self-integrating Rogowski coil with different layers is checked using different stages of the impulse-current generator, linear and nonlinear loads, and coil termination resistances. It is found that at a termination resistance of 1.1 Ω, satisfactory impulse current waveforms are measured by taking the commercial impulse current transformer as a reference signal. Results reveal that the magnitudes of measurement errors for the current peak, and front and tail times are <1.4%, <1.9%, and <4.5%, respectively. Overdamped impulse currents are generated by different generator capacitances, where impulse currents measured by double- and triple-layer coils have shown good agreement to those measured by the commercial devices. The trend of the results is also explained in terms of reflection, coil transit time and sensitivity bandwidth.