Novel designs of wideband Rogowski coils for high pulsed current measurement

This study presents design, calibration and testing of six novel flat-spiral self-integrating Rogowski coils wound in two layers. These coils are two varnished-wire wound coils with air and ferrite cores (RC1 and RC2, respectively), two flat-twin wire wound coils with air and ferrite cores (RC3 and RC4, respectively) and two coaxial-cable wound coils with and without the insulating jacket and with ferrite core and RC5 and RC6, respectively. All coil parameters are calculated and good agreement is found between these values and the corresponding measured ones. Coil sensitivity decreases as coil-to-wire separation increases and so does mutual inductance between the coil and the current-carrying wire. Linearity of all coil sensitivities are checked for different separations and waveforms, and good agreement is found. Designed coils with ferrite core give better response than those with air core because the low cutoff frequency decreases. On the contrary, the droop effect is slightly observed for coils wound on wooden core, where RC4 and RC6 give the best response. Finally, the frequency response analysis for all coils shows that the percentage relative errors of the measured and the calculated coil sensitivities are within ±0.1%.