The serial and parallel self-calibration of DC comparator up to 5kA

The deviation of serial and parallel ratios of direct current (DCC) comparator is investigated. By matching the currents passing the paralleled windings with the same nominal value, the deviation of the ratio of a group paralleled windings to the same group serial windings could be reduced to a negligible level. A suit of DCC with serial and parallel structure was developed to build the traceability of DC current up to 5 kA with uncertainties better than 1 times 10^-6.