Sealed Winding Conformance Testing and Recent Revisions to NEMA MG-1
Bibliographic record
Abstract
The sealed winding conformance test is often performed during the final acceptance test sequence for industrial motor stator insulation. The stator winding is first completely soaked with water, then receives a 10-minute insulation resistance (IR-io) measurement, followed by a 60-second high potential (hipot) test at 1.15 times rated line-to-line voltage (Vll). A 1-minute insulation resistance (IR-i) test is performed immediately after the hi-pot test. To define the test requirement, API 541 and 546 standards reference NEMA MG-1 20.18, which specifies an acceptance criterion for both IR measurements of (MOmega) ges VLL+ 1, where [VLL+ 1] is in kV. NEMA MG-1 20.18 refers to IEEE Std 43 for the insulation resistance test method and minimum insulation resistance. Until its most recent revision, IEEE Std 43 recommended the minimum IRi (MOmega) ges VLL+ 1 (kV). However, the current version of IEEE Std 43 (2000) recommends IR1ges 100 MOmega for all stator windings built after about 1970. Modern epoxy-mica insulation systems should be able to meet this value when fully clean and dry. The wet conditions encountered during sealed winding tests may produce a different response in the insulation system. The sealed winding test is outside the scope of IEEE 43. The next revision of NEMA MG-1 20.18 will clarify the sealed winding test acceptance level of IR (MOmega) ges VLL+ 1 (kV). This paper investigates the effect of test solution conductivity on the IR measurement, provides the NEMA-approved clarification of the sealed winding test specification and suggests further clarifications to the sealed winding test procedure.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.014 | 0.030 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.006 | 0.002 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.007 | 0.007 |
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".