Improvement of Hall Effect Current Transducer Metrological Performances in the Presence of Harmonic Distortion

The performance of Hall Effect Current Transducers (HECT), under distorted waveform conditions, are usually characterized by means of the frequency response test. In this paper it was investigated if the frequency response is able to correctly evaluate the ratio and the phase errors under distorted conditions. Two HECTs, with the accuracy class level of 1% and 0.5% respectively, were experimentally characterized under two conditions: 1. sinusoidal excitation with frequencies from 50 to 750 Hz, which is the well known frequency response test; 2. nonsinusoidal excitation using fundamental frequency and one harmonic, with adjusted amplitude and phase shift. It was found that ratio and phase errors are weakly affected by the harmonic amplitude and phase shift respect to the fundamental in the accuracy level of 0.1% and 0.05 deg. They have, instead, a strong dependence from conductor location in the HECT window. These results suggest that the frequency response approach for the evaluation of HECT performance, under distorted waveform conditions, can be used for an error compensation method only if the position of the primary conductor is known. An error compensation method, based on the frequency response, was implemented and tested with a distorted waveform composed of fundamental and many harmonics. For each of the harmonic components the errors were reduced to 1/10 of the measured ones.