The measurement of the frequency response of power transformers is a diagnostic methodology for detecting winding deformation and core displacement (along with other mechanical and electrical diagnostic methodology), which acts as the most important agents for the detection of mechanical failure in transformers. There are two different methods to carry out the measurement of frequency response: Sweep Frequency Response Analysis – (SFRA) and Low Voltage Impulse – LVI. SFRA has the upper hand over LVI such as: higher signal to noise ratio, higher repeatability and reproducibility and less measuring equipment required. It is based on comparison between; 1) earlier measurement on same transformer, 2) measurement on sister transformers, or 3) phase to phase comparison on same transformer with higher signal to noise ratio, higher repeatability and reproducibility and less requirement regarding measuring equipment. SFRA is an electrical test that provides information relating to transformers mechanical integrity. This paper details with use of sweep frequency response analysis (SFRA) as a diagnostic methodology to detect winding deformation and core displacement in power transformers. Practical case studies are presented that demonstrates the effectiveness of this methodology.