Diagnosis of winding displacement in power transformer using Frequency Response Analysis technique

The reliability of in-service power transformers is most important for a safe and economic operation of electrical networks. One possibility is to extend the monitoring and diagnoses of power transformers to all possible types of faults including its ability to withstand the short circuit forces. Nevertheless, this ability can be affected by thermal and mechanical stresses that occur during operation, which can cause displacement of winding in the transformer. In today practices, Frequency Response Analysis (FRA) is used as diagnostic tool for detecting winding movements. This paper presents a method for analysing the FRA results on distribution power transformers using correlation coefficient technique. Analysis was made on healthy transformer and also on transformer having an internal fault.