A New Calibration Method for Current Transformers Based on Full-Range Energized Conditions

Aims: This study aims to propose a new method to realize full-scale calibration of current transformers under energized conditions. Background: The calibration of low-voltage electromagnetic current transformers for metering under energized conditions is affected by primary current harmonics and noise, which makes it difficult to accurately carry out full-range calibration. Methods: In order to address this problem, this paper first introduces the equivalent circuit of a current transformer and carries out the error analysis at different frequencies. Then the current transformer, based on the background current offset full-range charged conditions of the frequency calibration method and the heterodyne current calibration method, isproposed, and the advantages and disadvantages of the two different methods are compared and analyzed. Results: A calibration method based on primary current cancellation and heterodyne current injection is proposed by combining the advantages of these two calibration methods and experimentally verified. Conclusion: The results show that the IF method based on background current offset can be applied to some conditions, but the heterodyne method without primary current offset is not suitable for calibration, while the calibration method based on primary current offset and het-ero-dyne current injection can be applied to a wide range of conditions.