Influence of temperature on frequency response analysis of transformer winding

Frequency Response Analysis (FRA) has been operated since last decade as a sensitive method in transformer internal defect recognition. This study has concentrated on influence of temperature variation of the transformer winding on FRA trace. An oil-free single phase model transformer involving concentric LV and HV windings is taken as a test object. The test object temperature is changed widely from low to high temperatures and the frequency response traces of the windings are recorded. In addition, a pair of winding discs including oil filled metal container is taken as another test object and its frequency response traces are recoded for various temperatures. FRA traces deviations as well as total capacitance variation due to the temperature changes in transformer windings are elaborated and discussed.