A self-calibrating high-precision current transformer

A self-calibrating current transformer with nominal ratio 10 A to 100 mA, intended for low frequencies applications, was developed. It has 100 independent primary windings to be connected in series or parallel, so that it can be configured as 100:1 or 1:1 transformer (all windings in series). This last ratio permits autocalibration. Error sources are analyzed, and it is shown that differences between parallel and series configurations have uncertainties lower than 1 part in 10⁶.