Technical condition assessment of power transformer windings after impact of short-circuit current

Abstract In the article the issues of technical diagnostics of power transformers windings are considered. Results of windings condition assessment using impedance measurements, frequency-response analysis and fi ed-frequency phase parameters measurement are presented. It is noted that the method for winding condition assessment based on phase-parameters measurement has potential for application on-site due to the rapidity of analysis, simplicity and availability of numeric criterion. Materials and methods Power transformers and methods for its condition assessment. Results Assessment of transformer winding fault was conducted using frequency and phase analysis. Conclusions To evaluate mechanical and electrical condition of the transformer windings, it is advisable to use frequency response analysis (FRA) along with traditional measurement of short-circuit impedance. The possibility of quick condition assessment of the windings using the method based on comparison of currents ratio at selected frequencies is shown. Also it is shown that phase method based on comparison of phase angle between winding current and voltage at the fi ed frequencies has suffi iently high sensitivity to winding deformation and faults.