Detection of transformer winding deformations based on the transfer function - measurements and simulations

Improvement of diagnostic methods for both power and distribution transformers is crucial considering the part they play in electrical networks as well as their cost. Transfer function based testing of transformers is one of the methods that has been introduced recently. This method enables the identification of winding deformations resulting from the short circuit currents and winding dislocations occurring during transportation, and can also be used to assess the state of electrical insulation. The methods of measurement of the transfer functions as well as the numerical simulations are aiming at determining the sensitivity of this method and to develop recognition criteria with regard to the type and range of the deformations. This paper presents a comparison of measurements and numerical simulation results of the transfer function performed on a medium-voltage transformer winding. A quantitative analysis of deformation detection and winding dislocation by means of the transfer function method is described.