On-line measurement of partial discharges on large motors in a generating station
Bibliographic record
Abstract
For several decades, off-line and/or on-line partial discharge (PD) measurements have been used for condition assessment of stator insulation systems in motors and generators. Many large critical motors in fossil and nuclear generating stations have surge capacitors installed on their phase terminals. On-line PD measurements on eight such motors were done without contact with high voltage terminals in Ontario Power Generation (OPG, earlier Ontario Hydro) by installing high (or radio) frequency current transformers (HFCT or RFCT) and line frequency current transformers (LFCT) on the grounding leads of the surge capacitors. The PD and line frequency voltage signals were picked from the HFCT and the LFCT, respectively. Passive filters were used to eliminate interference from high magnitude pulses generated by exciters in the generating station. A commercial instrument analyzed the PD pulses in terms of magnitude and relationship to the phase of the line voltage. Measurements have been repeated several times. This paper presents the the results obtained so far. Separate off-line tests on a similar motor showed that the HFCT method is at least as sensitive as the conventional OPG method, which uses a capacitive coupler, a wide-band filter, and an oscilloscope.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
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".