Frequency Response Measurement of a Power Transformer

This paper presents a field experience in condition monitoring of a power transformer using SFRA technique. A design based comparison approach of the SFRA test results is discussed in the paper. In order to verify the latest condition of the transformer, the SFRA test was complemented with DGA and PD tests. The SFRA test results indicated that there is an abnormality within the transformer windings. The PD test results confirmed this interpretation, where very large ultrasonic impulses were detected. A series of DGA tests have showed that there is an early stage degradation of the insulating paper, which may be associated with fault within the transformer windings. The field experience showed that the monitoring approach has been very useful in indicating the possible occurrence of failure within the transformer structure.