TriboTech ApS
Expert Tribology Consultancy
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Read one mineral-oil sample against the CO/CO₂ paper-involvement criteria of IEC 60599:2022, IEEE C57.104-2019 and CIGRE TB 771 (2019) — side by side, with no verdict. The three do not agree, and the disagreement is the result.
Three published sources put a bound on CO and CO₂ as evidence of paper involvement, and they do not agree. IEC 60599:2022 §5.5 (printed p. 15) pairs CO₂ above 10 000 ppm with a CO₂/CO ratio above 10, and concludes mild overheating of paper OR oil oxidation — a disjunction that is kept intact here. IEEE C57.104-2019 Annex D.8 c) (printed p. 69) needs three conditions, CO₂ above 10 000, a ratio above 20 and furans above 5 µL/L, for slow degradation of paper below 140 °C. CIGRE TB 771 (2019) App. E.2 (printed p. 58) reports a correlation with low average DP for a cumulative CO₂ above 15 000 ppm and a ratio above 20, where "cumulative" is defined as the pre-degassing value added to the post-degassing one. At the low end the two standards contradict each other on the same numbers: IEC 60599 §5.5 reads high CO with a ratio below 3 as probable paper involvement in the presence of other fault gases, while IEEE C57.104 Annex D.8 a) reads the same figures WITHOUT significant hydrocarbons as explicitly not a paper fault, attributing them to oil oxidation under limited oxygen, and only Annex D.8 b) — together with hydrocarbons — as a possible paper fault to be confirmed by Pentagon 2 and Triangles 4 and 5. Every bound above was read in the cited clause at the cited printed page. Where an input is missing the row says which condition could not be evaluated rather than assuming it; a CO of zero withholds the ratio instead of reporting an infinite one; and for a fluid other than mineral oil nothing is evaluated at all.
The tools are calculation tools made available free of charge by TriboTech ApS as part of the professional communication of its engineering consultancy. The tools perform a calculation based on the values entered and the published methods identified. They do not constitute an examination of an asset, a diagnosis, or advice on any specific asset. The tools have no knowledge of the asset's design, history, loading or operating conditions, and a result cannot therefore serve on its own as the basis for a technical or operational decision. A result is an indication, not a diagnosis. Use of the tools does not create a client relationship and does not create an advisory relationship. TriboTech ApS provides advisory services only under a concluded framework agreement, and no advisory liability is assumed for the use of results from the tools outside such an agreement. Any decision taken on the basis of a result — including a decision not to act — is taken by the user on the user's own professional judgement and at the user's own risk. As CIGRE itself puts it: "Actual actions on the equipment are the sole responsibility of engineers in charge of the transformers" (CIGRE Technical Brochure 771, 2019, section C.8, printed page 54). Each tool states which published methods and which editions the calculation is based on. The standard itself is the authoritative source, and a standard may have been revised since the edition a tool uses.
Method implementation — The calculation behind this tool is versioned. When a correction changes the result the tool gives for the same input, the version below changes with it. Version 1.0 · 02-09-2026. What changed, and when
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