How should a DGA report of transformer oil be interpreted?

Interpret DGA by trending gas concentrations and ratios over time, not by a single snapshot. Key gases indicate different fault types: hydrogen and methane often suggest low energy electrical activity or partial discharge, acetylene can indicate arcing, ethylene can indicate high temperature overheating, and CO and CO2 relate to paper insulation degradation. The report should be evaluated against the transformer’s history, load, temperature, and recent events, then combined with electrical tests and inspections to decide urgency and corrective actions.