Aged oils reclamation: Facts and arguments based on laboratory studies
Bibliographic record
Abstract
Lifetime extension of power transformers is a subject of high importance for electric power systems utilities. The decision of replacing, refurbishing or repairing a service aged power transformer requires considering several factors, especially the cost and time to execute the work. The lifetime of the power transformer being related to the condition of the insulation system; one way of improving the situation is to reclaim insulating oil by Fuller's Earth treatment. This procedure is economically attractive because of increasing prices for both mineral and synthetic transformer coolants, effective cost and environmentally sounds. Reclamation rejuvenates the transformer oil by eliminating contaminants. In this paper, a series of experiments has been performed with service aged oils reclaimed in laboratory conditions. Fast, inexpensive and reliable laboratory testing procedures developed by ASTM (D 6802 and D6181) were also used to monitor decay products as traces impurities. The results obtained in laboratory conditions, indicate that a large number of reclamation passes (around 15 passes) are required to regenerate inservice aged oil to a grade close to new oil. It is also shown that not only the reclamation improves the gassing tendency of oil, but also the type of Fuller's Earth is very important for reclamation process. By upgrading the analytical chemistry of oil, the predictive maintenance of this non-renewable resource is modernized, its cost diminished and the service reliability of transformers enhanced. Currently, Fuller's Earth is only used once. After depletion it must be disposed of in a land fill. By using two organic solvents that are recoverable by atmospheric distillation, it is shown, in laboratory conditions, that this mineral absorbent can be reactivated and successfully reused many times.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.003 |
| Scholarly communication | 0.001 | 0.004 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".