Localization of deformations in transformer windings using terminal capacitance measurements

The use of few terminal capacitance measurements at selected high and low frequencies can help in determining the location and extent of deformation in a transformer winding. A deformation coefficient derived from the measurements is used for this purpose. The mathematical basis and characteristics of the coefficient are elaborated. The method is tested for detecting radial and axial deformations in a real size coil. Two case studies involving radial and axial deformations are presented to demonstrate the efficacy of the approach. The suitability of the method for detecting combined axial and radial deformations is also demonstrated. Finally, the method is validated on a 500 kVA transformer.