SWEEP FREQUENCY RESPONSE ANALYSIS (SFRA)AN APPROACH TO DETECT HIDDENTRANSFORMER FAULTS

Sweep frequency response analysis is a major advance in transformer condition analysis. Frequency response is performed by applying a low voltage signal of varying frequencies to the transformer windings and measuring both the input and output signals. The ratio of these two signals gives the required response. This ratio is called the transfer function of the transformer from which both the magnitude and phase can be obtained. Changes in frequency response as measured by SFRA techniques may indicate a physical change inside the transformer, the cause of which then needs to be identified and investigated.