Verification of a calibration system for power quality instruments

A versatile calibration system that is suitable for calibration of power quality instruments has been built at Swedish National Testing and Research Institute. The instruments to be calibrated are intended for measurements under nonsinusoidal conditions and should be verified for such conditions. Therefore, the calibration system uncertainty for measurement of harmonics, especially in the presence of a large fundamental harmonic, is analyzed. The analysis is based on common A/D converter characterization techniques which are adapted for this special application.