Influence of Measurement Parameters on Frequency Response Analysis Diagnosis of Oil-Immersed Transformer

Appropriate monitoring and maintenance become important as an oil-immersed transformer ages. Generally, dissolved gas analysis (DGA) is effective for the online diagnosis, and if an abnormality is detected, frequency response analysis (FRA) is effective for the offline diagnosis to localize the failed part. FRA diagnosis detects a slight change of waveforms; however, external factors may influence the results. Here, we discuss the influence of an insulating oil presence, tap position, and measurement lead wire length as possible parameters that influence the FRA characteristics. We confirmed that the measurement parameters examined here greatly influenced the FRA characteristics. In the actual diagnosis, it is important to remove these external parameters as much as possible, and keep a detailed record of the measurement parameters. (c) 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(1): 18-25, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22313