1. Overview
Oil-immersed transformers use mineral oil for insulation and cooling. Proper maintenance is critical for service life. This guide covers DGA (Dissolved Gas Analysis), oil testing frequency, and troubleshooting per IEC 60076-2.
2. Maintenance Schedule
- Daily: Visual inspection, oil level, temperature
- 6 months: DGA sampling
- 12 months: Oil breakdown voltage test
- 36 months: Full oil analysis + dielectric test
- After fault: Immediate DGA + winding resistance
3. DGA Alarm Thresholds (IEC 60599)
| Gas | Threshold | Indication |
|---|---|---|
| Total combustible | >720 ppm | Investigate |
| Acetylene (C₂H₂) | Detected | Immediate action |
| Carbon monoxide (CO) | Rising | Paper degradation |
| Hydrogen (H₂) | >140 ppm | Arcing suspected |