Abstract:Power transformers are one of the most important equipment in the power system, and the angle & ratio difference test is a necessary means to ensure the accuracy of power transformers. Due to the complex condition on site, checking the fault can be very difficult when the test fails. To solve this problem, this paper discusses six typical on-site test faults of power transformers combined with actual field cases, analyzes the fault characteristics, fault causes, occurrence locations and other dimensions, and summarizes the general ideas and suggestions for fault troubleshooting by extracting the characteristics of typical faults and combining the detection information given by the calibrator. At the same time, the prominent safety risk points in the testing process are analyzed and suggestions for troubleshooting are put forward. Through the analysis and discussion of this paper, it is hoped to provide the method guidance of troubleshooting for the staff, deepen the understanding of the principle of angle & ratio difference test of power transformer, reduce the operational risk, ensure personal and equipment safety, and contribute to the safe and stable operation of the power grid