A Study on Detecting Winding Deformation in Transformers with FRA Method

Terminal fault on transformer is the main reason to cause transformer faults because it can take obvious accumulation effect on mechanism strength of windings． So detecting winding deformation immediately is very important to decrease transformer faults． The paper introduced the principle of Frequency Response Analysis （FRA） method to detect winding deformation and the several key problems that must be solved before it can be applied in test on site． The different test connection type for detecting winding deformation was presented and the typical test circuits was given． Through the field test， the relationship among FRA result curves and switch position， signal location， bushing capacitor and the lead length of transformer was analyzed． Based on the practical test data on 158 transformers， the criterion was presented to judge winding deformation with FRA method．