Transformer TX-204 in the analyzer's demonstration fleet: acetylene has more than doubled in six months. Ratios, Duval coordinates, IEEE C57.104 status and what to do next.
| Transformer | TX-204, 220/132 kV, 160 MVA, OFAF, sealed, mineral oil, built 2014 |
| Latest sample (ppm) | H2 210, CH4 70, C2H6 18, C2H4 55, C2H2 140, CO 360, CO2 2 800 |
| Trend | TDCG 424 → 607 → 853 ppm over two years; C2H2 rising 0.40 ppm/day |
Open the DGA Analyzer and click TX-204 in the fleet to follow along.
| Ratio | Value | D1 range (Table 1) |
|---|---|---|
| C2H2/C2H4 | 140/55 = 2.55 | > 1 |
| CH4/H2 | 70/210 = 0.33 | 0.1 – 0.5 |
| C2H4/C2H6 | 55/18 = 3.06 | > 1 |
Rogers ratios and Duval Pentagon 1 point to D2 (high-energy arcing); Pentagon 2 to D1. The analyzer weighs the methods and reports D1 with 42 % confidence, D2 29 % as the next candidate.
Acetylene is at more than 5 × the Table 2 limit and H2, C2H4 and C2H2 all show significant increases between samples.
| Check | Requirement | Actual | Status |
|---|---|---|---|
| IEC 60599 fault type | Table 1 | D1 — low-energy discharge | ✗ FAIL |
| Duval Triangle 1 | Zone | D1 | ✗ FAIL |
| IEEE C57.104 status | Status 1 = normal | Status 3 — Extreme | ✗ FAIL |
| Paper involvement (CO2/CO) | 3 – 10 | 7.8 | ✓ PASS |
Key insight: Methods disagree near the D1/D2 boundary. The rate of increase of acetylene, not the exact zone, decides how urgent the response is.
Every input in this example is editable in the live calculator — no signup needed.
Open DGA Analyzer (Transformer Oil) calculator →D1 and D2 sit next to each other on every method. A sample near the boundary can fall on either side; the analyzer shows all methods so you can see the spread.
Yes, if the OLTC compartment leaks into the main tank. IEC 60599 §5.7 flags C2H2/H2 above about 2–3; here it is 0.67, which does not indicate contamination.