Evaluation of Grading System of Large Motors AC Stator Windings
Bibliographic record
Abstract
In this paper, the field dependent characteristics of different stress grading tapes used for high voltage form-wound coils have been examined. High voltage insulation systems require voltage stress grading to suppress the potential gradient and to ensure proper operation. Without these materials, the electric fields in the endarm region will lead to discharge in the surrounding air with potential degradation of the insulation system. The grading materials used in this investigation were woven polyester fabric tape loaded with semi-conductive varnish that included silicon carbide. In order to determine if the vacuum pressure impregnation (VPI) epoxy resin has an influence on grading performance, surface potential within the stress grading regions of sample coils was measured at test voltages of 8 kV and 14 kV. The measurements were performed prior to VPI (at green stage), after pre-bake at 160degC, and post VPI. The influence of high resistive surface contaminants on the grading was also examined. The experimental results reveal that introduction of the VPI resin can influence the electrical characteristics of the grading systems. In addition, a high resistivity contaminant can influence the performance of the grading system.
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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 | 0.000 | 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) | 0.001 | 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".