Dissolved Gas Analysis (DGA)
Definition
The analysis of gases dissolved in transformer oil (H2, CH4, C2H4, C2H2, CO, CO2) by ASTM D3612 or IEC 60599 to diagnose incipient fault types: acetylene indicates arcing; methane and ethylene indicate thermal faults; CO and CO2 indicate cellulose degradation.
- Sample
- Gases dissolved in transformer oil
- Key gases tracked
- H2, CH4, C2H4, C2H2, CO, CO2
- Standards
- ASTM D3612, IEC 60599
- Arcing marker
- Acetylene (C2H2)
- Cellulose degradation markers
- CO and CO2
Common questions
How does DGA help distinguish an accidental transformer failure from a deliberate one?+
The gas ratio pattern points to a fault mechanism, arcing, thermal overheating, or paper insulation breakdown, so an investigator can check whether the pattern matches a known accidental failure mode or looks inconsistent with the transformer's service history.
Why is a single gas reading not enough to diagnose a fault?+
Individual gases can arise from normal aging as well as faults, so IEC and ASTM interpretation methods use gas ratios and trend over time rather than one absolute concentration to identify the fault type.
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