Accurate High Direct Current Measurements for Industry

Calibration of high dc current transformers, dc ammeters, and dc current range extenders can be carried out simply using a high quality dc current transformer, an uncalibrated high current source and a calibrated low current source. The method, called the Current Reference Step Method, utilizes a buildup technique that exploits the ability that a de current transformer possesses to accurately sum the currents through its window with excellent differential linearity. Uncertainties of several parts per million in the applied high current can be achieved.