Experience with partial discharge measurements on instrument transformers in high voltage laboratory acceptance tests
Bibliographic record
Abstract
This paper highlights high-voltage laboratory acceptance tests performed by Manitoba Hydro on new 230kV current transformers (CTs). In performing these tests it was revealed that a number of CTs failed to meet requirements for partial discharge (PD). For the performance of PD tests, a modern digital PD measurement instrument was used. This instrumentation proved valuable in its ability to produce phase-resolved PD pattern plots which could be analyzed for identification of the defects causing discharge. From this work, much has been learned about the nature of PD in oil-paper insulated instrument transformers. Evidence from phase-resolved PD measurements suggested the presence of gas-filled voids within the insulation producing PD. It has been observed that PD in oil-paper insulation has some peculiar qualities; PDs can incept, then extinguish, and then re-incept, all while voltage stress may be held constant. Additional evidence suggests that the discharge activity may be influenced by exposure to extended periods of overvoltage prior to test. Findings show that extended exposure to overvoltage prior to PD measurement may cause instrument transformers to falsely pass PD tests.
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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 | 0.005 | 0.011 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| 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".