The application of a simple binary step up method for possible calibration of high current DC shunts up to a few thousand amperes in which a pair of HCDC shunts are used to evaluate the current dependence of the shunt resistance. It was found that a complex exponential linear model can be applied to separate the drifts in voltage measurements from the contribution of the current coefficient of the shunt. This approach allows one to extract the information on the current coefficient of the shunt and together with low current measurement of the shunt resistance to calibrate the current output of HCDC source, which in turn can be used as a reference for calibration of customer's shunts. In order to validate the step up method, the calibrated HCDC source was used to obtain DC current ratios which is to be compared with NRC's high current ratio measurements of a multi-ratio 3000 A reference DC CT.
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