Effect of antenna position on on-line monitoring of transformer winding axial displacement using electromagnetic waves

Mechanical or electromechanical forces can cause axial displacement of transformer winding. Using electromagnetic waves is a new measuring method for the detection of axial displacement and radial deformation of windings. This method can be used for off-line or on-line applications. In this paper, it is shown that the upward and downward axial displacement of the high voltage and/or the low voltage winding can be detected by the on-line monitoring of the scattering parameters. In the proposed method the low voltage windings have been modeled and in the model, the electromagnetic waves are transmitted from an antenna and the reflections have been saved in a data bank. The best antenna position for detecting the axial displacement of windings has been determined by comparing the results of different simulations.