A simple traceable current transformer calibration method

A simple traceable mains-frequency current transformer ratio build-up scheme has been developed which enables calibration of ratios from 5 A:5 A to 500 A:5 A with uncertainties of 0.05 /spl mu/A/A and 0.05 /spl mu/rad. The build-up is based on series-parallel interchange of primary windings of two-stage transformers with magnetically shielded second stages.