What is DGA Testing?
DGA is a key diagnostic method for evaluating the internal health of oil-filled transformers. Electrical and thermal stresses cause decomposition of insulating materials, generating gases that dissolve in the oil. By analyzing the type and concentration of these gases, DGA helps detect developing faults early. It’s a non-intrusive, reliable technique essential for transformer condition monitoring and preventive maintenance.
How is DGA useful?
Transformers are vital and high-value assets in power systems. Any internal fault can lead to catastrophic failure, system downtime, and fire hazards. Early detection of incipient faults through DGA helps in:
- Identifying the type of fault (electrical, thermal, or combined).
- Assessing the severity of insulation degradation.
- Planning preventive maintenance or corrective actions.
- Avoiding unexpected transformer outages and costly breakdowns
Applications of DGA
Dissolved Gas Analysis (DGA) helps in identifying incipient faults in transformers by detecting the type and level of gases dissolved in the oil. Each gas has diagnostic significance, and its presence or increase beyond normal levels points to specific fault conditions.
Typical Scope of DGA Study
- Collection and analysis of transformer oil sample (in compliance with IS standards).
- Laboratory analysis of dissolved gases using Gas Chromatography (GC).
- Identification of gases such as H₂, CH₄, C₂H₆, C₂H₄, C₂H₂, CO, CO₂.
- Correlation of gas levels with possible internal faults.
- Evaluation of oil quality for comprehensive health assessment.
Benefits of DGA Testing
- Early detection of incipient faults.
- Reduction in forced outages and downtime.
- Improved safety of the plant and personnel.
- Enhanced reliability and life expectancy of the transformer.
- Compliance with international standards and best practices.
Methodology
- Pre-Audit Questionnaire
- Audit & Sampling
- Laboratory Analysis
- Discussion & Review
- Report Submission