A New Method for the Calibration of a National Current Ratio Standard

A method is proposed for the self-calibration of a compensated current comparator. At first, with a unity ratio (5A:5A), an interrelation is established between the errors and the remaining magnetic fluxes, both in the compensated comparator configuration and in the current transformer configuration. These errors can be measured directly and the fluxes can be observed by means of a detection winding voltage. For the nonunity ratios (>5A:5A), the knowledge about this interrelation is incorporated to determine the errors with a measurement uncertainty of less than 5 × 10-7.