The mineral oil will contain normal values of dissolved gas which will indicate no incipient fault in the transformer. The following figures show the normal values of dissolved gases in the oil. When the DGA results of all the 7 key gases are less than the values of figure, it can be concluded there was no incipient fault in the transformer.
H2: 100ppm
CH4: 50ppm
C2H6: 50ppm
C2H4: 50ppm
C2H2: 5ppm
CO2: 5000ppm
CO: 200ppm
