Expert Tribology Consultancy
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Estimate paper degree-of-polymerisation (DP) from a measured oil 2-furaldehyde reading, across the four published models (Chendong, De Pablo, Pahlavanpour, Shkolnik) shown side-by-side with their spread. Advisory only — uses the raw lab 2-FAL, not a temperature-corrected value.
1.0 ppm 2-FAL, kraft paper
5.0 ppm 2-FAL, kraft paper
2.0 ppm 2-FAL, TU paper → Shkolnik
2-FAL reported below the detection limit, entered as 0 ppm
The four empirical furan-DP models are reproduced in IEEE C57.140-2017 (Eqs 7–10, p.30): Chendong DP=(1.51−log₁₀F)/0.0035 and Shkolnik DP=(1.17−log₁₀F)/0.00288 (log-linear); De Pablo DP=7100/(8.88+F) and Pahlavanpour DP=800/(0.186·F+1) (hyperbolic). The calculator feeds the RAW lab 2-FAL (ppm): none of the four equations has a temperature term, and each takes the 2-FAL content of the oil in ppm as its input (IEEE C57.140-2017, §5.4.2). CIGRE TB 779 normalises marker concentrations to 20 °C to track cellulose ageing (§6.4, §9.1); TriboTech does not apply that correction before DP estimation, so a temperature-corrected F must NOT be used here. Paper type selects the applicable models (kraft → Chendong/De Pablo/Pahlavanpour; thermally-upgraded → Shkolnik); if unknown, all four are shown so the spread (more than 300 DP units between about 1 and 15 ppm) is explicit. Estimates are advisory and more likely too high than too low — real paper is typically more degraded (CIGRE TB 735) — and never a stand-alone de-energisation basis. A 2-FAL below the detection limit, entered as 0 ppm, is treated as a real reading rather than an input error: the calculator returns no DP — the log-linear models are undefined at F = 0 and the hyperbolic models return only their new-paper anchor — and says so explicitly.
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 calculations behind the tools on this site are versioned. When a correction changes the result a tool gives for the same input, that tool's version changes with it. What changed, and when
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