High voltage power transformer diagnostics using vibroacoustic method

Processing and analysis results of vibroacoustic signals generated during the switching process of electric power transformer are presented in the paper. Three cases are considered: (1) the transformer has no defects, (2) the pressing screws of the upper yoke were slackened and (3) the pressing screws of both the upper and lower yoke beams were slackened. Further the measuring transducer was placed at four different locations on the transformer tank surface. The gathered signals have been analyzed in the frequency domain by use of the power spectral density function. The magnitude of the first eight harmonics, included in the measured signals, is subjected for comparative analysis.