Hybrid Dissolved Gas-in-Oil Analysis Methods

Dissolved gas analysis is the most widely used diagnostic test in power transformers. The aim of this paper is to introduce the dissolved gas analysis (DGA) methods able to diagnose the transfor-mer conditions. The faults cause the transformer oil, pressboard, and other insulating materials to decompose and generate gases, some of which dissolve in the oil. The results of DGA must be ac-curate if faults are to be diagnosed reliably. There are different established methods used in in-dustry for interpreting DGA results. We will compare the result of IEEE Key Gas Methods and Rog-ers ’ Ratios. The transformer conditions are evaluated by the Key Gas Method with total combusti-ble gas method (TCGM) and then verified by the Rogers ’ Ratios. As result, the aging pattern and trend of the power transformer deterioration can be determined. The 30 sample data from IEEE with known faults and dissolved gas concentrations were used as the basis of comparison