Discrimination Between Radial Deformation and Axial Displacement in Power Transformers Using Analysis of Electromagnetic Waves

In recent years, the electromagnetic wave application has been proposed for the detection of mechanical defects in power transformer windings. After detection of a defect, the determination of defect type is the next stage of monitoring. In this paper, a comparative method is presented to discriminate between radial deformation and axial displacement in power transformer high-voltage winding using electromagnetic waves. In this paper, the magnitude Euclidean distance (MED) index is used to compare the received signals in sound and defective conditions. In the proposed method, two receiving antennas and one transmitter antenna are used to emit ultra wideband signals to the winding and receive their reflections. Two receiving antennas receive signals at two different positions, as a result, in the case of a mechanical defect occurrence, the amplitude of the received signals and the MED index will be different. Hence, taking the advantage of this feature, the type of defect can also be determined after its detection. The proposed method is evaluated by a simulated model, and then, experimental tests are conducted on an actual transformer winding to show its validity.