Diagnosis of Abnormality of Transformer Winding by Frequency Response Analysis

Deformation and/or displacement of transformer winding are hazardous because electromagnetic force generated by a short-circuit current may increase. Frequency Response Analysis (FRA) has the possibility to detect these abnormalities with high sensitivity. In this paper, fundamentals and diagnosis method of power transformers by FRA are introduced. Examples of applications of FRA such as detection of deformation of winding due to short-circuit tests, detection of disconnection electrostatic shield, and detection of displacement of HV winding are introduced. Furthermore, recent researches related to interpretation of change of transfer functions are introduced.