Simple absolute method for current transformer calibration

Abstract

A simple mains-frequency current transformer ratio build-up scheme has been developed which enables calibration by absolute means of ratios from 5 A:5 A to 500 A:5 A with uncertainties of 0.03 parts in 10/sup 6/ 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.