Wide Bandwidth Rogowski Current Transducers

Abstract

This paper is the first of Two parts giving a comprehensive examination of the use of Rogowski coils for wide bandwidth current waveform measurement. Rogowski coils have previously been used for special applications of current measurement such as very short duration high current pulses, but have only recently become available as general purpose transducers suitable for power electronic equipment. This requires a bandwidth of 50 Hz to at least I MHz for performance comparable to a standard co-axial shunt. Part I examines the coil behaviour and its implication for the integrator design in terms of sensitivity, drift, noise and bandwidth. It is shown, contrary to previous pronouncements, that the coil screen is not advantageous and that improved bandwidth may be obtained by situating the integrating resistor in the coil assembly. Some practical measurements are provided. Part II will examine integrator behaviour and the overall transducer performance.