Comparative analysis between active and passive current transducers in sinusoidal and distorted conditions

Current measurements are a critical item in the monitoring of modern electrical power plants, since the quantities to be measured often show high harmonic content. The current transducers should therefore guarantee a good accuracy even when they operate with distorted waveforms. In this paper, the behavior of some devices commonly used for current measurement is examined, considering either sinusoidal or distorted conditions. Traditional current transformers, transducers based on the Hall effect, and resistive shunts combined with isolation amplifiers have been considered. The comparison is performed by evaluating a synthetic error index, called composite error, which allows all the main causes of uncertainty (amplitude errors, time shifts, and distortion) to be taken into account. The proposed investigation aims to find out the main characteristics that make each transducer suitable or unsuitable in different practical situations.