Abstract：In this paper a new structure and working principle of a high accuracy current comparator are introduced. A new circuit structure called “shielding drainage” is described to reduce the leakage capacitance coupling current between the turns of the secondary winding, it also reduces the additional error caused by combination of secondary winding. The accuracy of current comparator is better than 1×10-6 at ratio 5A/5A to 5000A/5A. A new self-calibration method for multi-ratio current comparators is also presented; the uncertainty of this new method is less than 2×10-7. The self-calibration methods should be widely used to solve the transport problem, contributing to its high accuracy, simple connection and convenient operation.
2025, Vol. 46 
