Effect of Shielding on Rogowski Coil Transducer Performance and the Equivalent Circuit Model

Abstract

Rogowski coil is sensitive to current surges in nearby systems. Hence, if it is used to measure a current in a system and a current surge occurs in a nearby location to this system, the coil senses this current in some degree. This means that the performance of the coil is affected by this current surge. Therefore, this article presents a low-cost shielding method depending on using aluminum foil sheets. The effectiveness of this shielding is studied through experimental results. The experimental study is carried out by building three similar coils. One of them is designed without shield with a return winding (RC1), the second coil is designed without shield with no return winding (RC2) and the third one is shielded using aluminum foil sheet (Rc3). Also, an impulse generator is used to generate high impulse current in a system that locates at different distances from the shielded and unshielded coils. The induced voltage signals in the three coils are captured using a digital oscilloscope. The captured voltage signals are used to evaluate the shielding performance of the coil. It is found that using shielding in Rogowski coil changes the coil model parameters. So, a shielded coil model is developed and presented. The validity of the proposed model of the shielded coil is examined by using impedance–frequency measurements which carried out using an accurate LCR meter. Finally, the efficacy of the proposed shielding method and the validity of the shielded coil model are validated through the obtained measurements.