A study of the engineering model of lightning strokes and its application to unshielded transmission lines
Bibliographic record
Abstract
A model is developed for determining the frequency, the characteristics, and the spatial distribution of the lightning flashes terminating on power lines, both the shielded and the unshielded types. The model takes into consideration the existence of the towers, the sag of the conductors, and the inequality of the striking distances to the different elements of the model (towers, wires, and the ground plane), and assumes the strokes to arrive in the vertical direction. In case of power lines, the striking distances to ground and to the wires are taken equal to the base striking distance, and the striking distance to the towers is taken to be in the range 1.0 to 1.1 times the base striking distance. In case of medium height masts, the striking distance to the mast is taken equal to 1.2 times the base striking distance. The median current to flat ground is taken equal to 24 kA. The model is used in an extensive quantitative analysis of the frequency and the characteristics of the strokes collected by power lines and masts and the spatial distribution of the flashes collected by power lines. The model successfully predicts available observations regarding the effect of height of structure on both the median current of the collected strokes and the protective ratio. The output of the model is used to calculate the outage rate of unshielded steel-structure power lines using a newly developed method. The study covers the voltage classes 230 kV, 500 kV, and 765 kV. A theory is provided explaining the discrepancies between measured and calculated striking distances. A preliminary generalized model for the termination of lightning flashes, both the upward and the downward types, on tall structures is proposed. The termination of lightning flashes at points below the top of a tall structure is explained, and a new method for designing the necessary shielding system is given. Finally, a three-dimensional model for the shielding effect of forests is developed and a quantitative analysis of the effect of height of trees, width of right-of-way, and voltage class of the line is provided.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".