Diagnostic Investigation & Correlation In-Service HV & EHV Current-Transformers Exhibiting High Levels of Hydrogen
Bibliographic record
Abstract
High levels of hydrogen have been observed in some current transformer (CT) units of the 72.5kV to 330 kV free standing-type using paper-oil insulation and inhibited mineral oil. Several techniques have been used by Trench and Hydro Québec (HQ) to investigate the possible causes of this high hydrogen formation, such as partial discharge tests, dissolved gas analysis, moisture content, dielectric dissipation factor and compatibility tests of the oil with metal parts. The most probable cause, stray gassing (slight overheating around 100°C) of the oil, occurred during the early operation of the units then disappeared, did not damage paper and oil insulation, and is not a concern for the normal operation of CTs. Indeed, all units with initially high hydrogen levels have continued to operate without any sign of electrical or thermal problems, and with hydrogen slowly diffusing out with time. Similar observations of normal operation with high hydrogen levels have been reported at CIGRE in CTs, bushings and small Padmount power transformers. CTs with high hydrogen contents due to this same cause could thus reasonably be kept in service rather than replaced. [3]
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 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".