Insight into SFRA responses & interpretations with regard to insulation system of transformer

Sweep Frequency Response Analysis is a proven test technique for condition monitoring of transformers. Detection of the change in geometry of core and coil assembly is the major intent of this test. With the experience of about a decade or two, the experts have laid out guidelines for this analysis to asses the electrical & mechanical health of this assembly. Though it is looked at as a tool to detect winding movement it is actually directing us to see if there is any change in insulation system within windings either due to movement of conductors or due to inappropriate thermal aging. A change is to be studied in all respect and not only related to movements. Nevertheless it is still a subjective assessment and complex to judge. The Subject is promising and this paper looks at further enhancement with a new concept to analyze and detect the degradation of internal winding insulation of transformer. Capacitance & power factor measurements used to asses bulk insulation is not sensitive to inter winding insulation such as inter turn insulation. With the help of two cases it proposes this concept to detect the degradation of internal insulation of transformer.