Currently available prediction models for dissolved gases in transformer oil are GM(1

1) and its improved forms

which have the drawback of considering only one gas separately. To make up for this disadvantage

the multivariable grey model MGM(1

n) is introduced to allow for the change in several indices described simultaneously. Thus

the prediction with the multivariable grey model has proved more scientific and effective. The relationship between seven dissolved characteristic gases

viz. hydrogen (H2)

methane (CH4)

ethane (C2H6)

ethylene (C2H4)

acetylene (C2H2)

carbon monoxide (CO)

and carbon dioxide (CO2)

based on the grey relational analysis theory is discussed. The MGM(1

7) model is then developed. Finally

the effectiveness and superiority of the proposed method has been verified with the result of an actual case.