Modern trend in Dissolved gas analysis in transformer and OLTC

Early detection of faults is called for in any equipment to prevent possible catastrophic failure during the service life. While many diagnostic and prognostic detection methods are employed, diagnostics based on DGA of transformers, OLTCs and Bushings have gained ground. Many techniques of DGA are propounded and many guidelines are drawn. A combination of diagnostic techniques and expert interpretation skills supported by a credible database is the key in the fault detection. OLTCs have largely followed the DGA guidelines of the transformers. DGA of OLTCs is presented and discussed in the paper. An analysis of the various DGA techniques available are reviewed in this paper with more emphasis on Duval Triangle.