Frequency response analysis approach for condition monitoring of transformer

The paper deals with the frequency response analysis (FRA) technique, which uses sweep frequency responses of the transformer winding to study the various aspects of winding deformations. Experimental and theoretical investigations were carried out on the HV disc winding of a 11 kV/433 V, 1 MVA transformer. Sweep frequency responses of this transformer were obtained experimentally. Theoretical computations of frequency responses using EMTP are made by representing the transformer winding as ladder network parameters, comprising inductances and capacitances that are computed from its design data. The paper presents the theoretical and experimental results and analysis of the frequency responses on the variations of the winding parameters, which represents the winding deformation.