How does transformer oil gas analysis identify developing faults?

Gas analysis, typically DGA, detects dissolved gases produced by overheating, partial discharge, and arcing. Different fault types generate characteristic gas patterns. For example, hydrogen can indicate partial discharge, acetylene strongly points to arcing, and ethylene or methane suggests thermal faults at different temperatures. By trending gas levels and their growth rates, engineers can identify early fault development before it becomes catastrophic. Interpretation uses ratio methods and limits, but the most reliable approach combines DGA trends with operating history, load, temperature, and any electrical test results.