Current AC-DC transfer measurements in the microampere range

A relation of the AC-DC transfer differences contributing to the current AC-DC transfer difference of a current shunt in combination with a thermal transfer standard with amplified millivolt ranges is given. Two step-down procedures for measurement of ac current in the microamp range using a thermal transfer standard with amplified millivolt ranges together with current shunts are described. The results of measurements using the two methods are compared and found to be in good agreement with the predictions.