Abstract:Safe, accurate and efficient calibration of transformer secondary circuit wiring is one of the difficult problems in substation construction and operation and maintenance. In order to get rid of the backward traditional line calibration method of substation secondary circuit effectively, this paper presents a method of line calibration of secondary circuit based on impedance detection transformer. Firstly, the existing secondary loop alignment methods based on multimeter and the current alignment methods based on AC power supply on-off detection are analyzed in detail. The principle of the traditional method is analyzed from the point of view of equivalent circuit and the defects and problems are clarified. Then, based on the deficiency of traditional methods, a secondary circuit alignment method of trans-former based on impedance detection is proposed. Secondly, according to the proposed method, the hardware circuit and software pro-gram of the secondary loop alignment device are designed and developed. At last, the calibration device was tested on site during the secondary circuit acceptance of the main transformer expansion project of a 220kV substation. The results show that the device can efficiently complete the calibration work of the secondary circuit of the current transformer, and the calibration device is simple and portable, with high calibration efficiency and accuracy.