Calibration of Precision Current Transformers and AC Resistors by Comparison using Two Sampling Digital Voltmeters

The paper presents a new highly efficient technique for the calibration of a current transformer, loaded by a precision shunt resistor, by comparison with a reference transformer - resistor combination. Two sampling digital voltmeters are used to measure the voltage output of each combination. The errors of the transformer and the resistor are measured without knowing the voltmeter errors. It is anticipated that the new technique will significantly simplify the calibration chain without adding appreciably to the calibration uncertainty of a few parts in 10−6.