TY - JOUR N2 - As it is found in the related published literatures, the transfer function (TF) evaluation method is the most feasible method for detection of winding mechanical faults in transformers. Therefore, investigation of an accurate method for evaluation of the TFs is very important. This paper presents three new indices to compare the transformer TFs and consequently to detect the winding mechanical faults. These indices are based on estimated rational functions. To develop the method, the necessary measurements are carried out on a 1.3 MVA transformer winding, under intact condition, as well as different fault conditions (axial displacement of winding). The obtained results demonstrate the high potential of proposed method in comparison with two other well-known indices. Additionally, two important methods for describing TFs by rational functions are studied and compared in this paper. L1 - http://www.journals.pan.pl/Content/84629/PDF/08_paper.pdf L2 - http://www.journals.pan.pl/Content/84629 PY - 2012 IS - No 1 March EP - 99 DO - 10.2478/v10171-012-0008-0 KW - transformer KW - transfer function KW - fault detection KW - axial displacement KW - rational function A1 - Bigdeli, Mehdi A1 - Vakilian, Mehdi A1 - Rahimpour, Ebrahim PB - Polish Academy of Sciences VL - vol. 61 DA - 2012 T1 - Comparison of transfer functions using estimated rational functions to detect winding mechanical faults in transformers SP - 85 UR - http://www.journals.pan.pl/dlibra/publication/edition/84629 T2 - Archives of Electrical Engineering ER -