A deviation index method to detect winding displacement in power transformer using FRA

The transfer function (TF) these days is a well-known method to detect different types of mechanical damage in power transformers. The most important mechanical faults which are most likely to be detected using the TF and occur frequently in transformers, radial deformation, and axial displacement. Since the TF method is a comparative method and the measured results should be compared with the reference results. In paper a new approach i.e. deviation index methods are studied to compare different TFs. A complete fault detection, which means determining the type, location, and level of the faults by using TF analyses, is the main aim of this paper.