What does DGA of transformer oil reveal about thermal and electrical faults?

DGA reveals whether faults are likely thermal, electrical, or a combination. Thermal faults tend to produce methane, ethane, and ethylene depending on temperature severity. Electrical faults such as arcing generate acetylene, often with hydrogen. Partial discharge commonly elevates hydrogen. Paper insulation involvement is suggested by rising carbon monoxide and carbon dioxide. By evaluating patterns and trending, DGA can estimate fault energy level, whether it is active, and whether the risk is increasing.