The Advantages of Sweep Frequency Response Analysis in Transformer Testing

Doble M5400 Sweep Frequency Response AnalyzerSweep Frequency Response Analysis (SFRA) is an electrical testing method which identifies changes to the internal workings of a transformer.  The transformer is an electrical filter that has a specific response to each independent input frequency. The test equipment is used to apply a test voltage to a transformer over a range of frequencies. 

The output of the transformer is then monitored in relation to its corresponding input frequency.  The results, when graphed, make up a signature response, much like a unique fingerprint. The initial SFRA test will then become a baseline for comparison when future tests are performed.  When these signatures do not match the baseline signature, something has changed internal to the transformer and merits further investigation.