Tony Wills - Application engineer
Sweep frequency response analysis (SFRA) testing on transformers provides invaluable information about the mechanical integrity of the transformer’s components – information that can’t be obtained in any other way without dismantling the transformer or at the very least, by performing a thorough internal inspection. Mechanical movement or deformations within the transformer produce changes in the transformer’s inductance and capacitance distribution. It is these changes that SFRA testing measures.
Some engineers and technicians however, find SFRA test results daunting to analyse, particularly if they have not had much experience with using this technique. Having comparative results, ideally from tests performed when the transformer was new or in known good condition, is a big help, because SFRA test results should not change throughout the life of a transformer. But when changes in the test results are seen, what do they signify? International standards organisations have developed guides and brochures to help answer this question but for those who prefer a more practical hands-on approach, Megger’s FDB101 demonstration tool is a very attractive alternative.