Study and diagnosis of key gases to assess condition of power transformers

The operating principle of transformers is based on the slight albeit harmless deterioration of the insulation that accompanies incipient faults, in the form of arcs or peaks resulting from dielectric breakdown of weak or overstressed parts of the insulation, or hot spots due to abnormally high current densities in conductors. Whatever the cause, these stresses will result in the chemical breakdown of some of the oil or cellulose molecules constituting the dielectric insulation. The main degradation products are gases, which entirely or partially dissolve in the oil under thermal and electrical stress conditions caused by faults currents in the transformers, the hydrocarbon molecules of mineral oil can decompose and form active hydrogen and hydrocarbon fragments and these fragments can combine with each other to form gases like hydrogen (H₂), methane (CH₄), acetylene (C₂H₂), ethylene (C₂H₄), ethane (C₂H₆) etc. The major contribution of present work is the study of different methods of Dissolved Gas Analysis for the incipient fault diagnosis of transformer also gives diagnosis to the variation of key gases of 110 different transformers of state electricity board to analyse condition of power transformer irrespective of manufacturing year and make.