Sampling current ratio bridge for calibration of current transducers up to 10 kA with 5 ppm uncertainty

A sampling current ratio bridge has been developed, tested and validated for the accurate complex ratio measurement of AC current transducers for primary currents up to 10 kA with expanded uncertainties of 5 · 10^-6 in magnitude and 5 μrad in phase (k = 2). A unique property of the system is the use of digitizers for sampling of the secondary current signals and step-down transformers with a large number of current ratios. This allows for the accurate calibration of a large variety of different current transformers and other types of current transducers.