Measurement of High Pulsed Currents Through Plates by Novel Linear Side-Looking Coils

This paper presents a design and calibration of six novel linear side-looking 'Rogowski' coils to measure impulse currents through plates. This special design of Rogowski coils enables the measurement of impulse currents in some applications, where such measurements are very difficult to be achieved using the toroidal Rogowski coils. The six designed coils are divided into two sets based on the coil-operating mode. The first set consists of three coils, which are wound in a single layer by varnished wires on perspex and ferrite rods, and they are operated in differentiating mode with external passive integrators. The second set consists of three coils, which are wound in a single layer or flat spiral by coaxial cables on ferrite rod or cylinders, and they are operated in self-integrating mode with non-inductive termination resistance. For each set of coils, the integrator parameters and coil-termination resistance values are optimized in order to have a wider bandwidth and to avoid any droop effect. The designed six coils are calibrated using different over damped unidirectional and oscillatory impulse currents up to 12 kA. Two commercial impulse current transformers, namely, ICT1 and ICT2, simultaneously measure these currents. The modeling results reveal that most of the designed coils have sensitivity in the range from few tens to few hundreds mV/kA and bandwidth in the order of MHz. Finally, the results are interpreted in terms of frequency response analysis, and the correlation between coil performance, and both the current density distribution in the plate and the produced magnetic flux density.