Research — Illustrative (draft, unvalidated)

Sag and tension across a deadend section

A deadend section: five poles, four spans, one conductor over rolling ground, a road, a walkway and open land. Change the loading and the whole line breathes: it sags deeper in the heat until the road span dips into its required-clearance band, then pulls tight in the cold until a low pole's insulator lifts. The section tension and ruling span update with it. Play six short stories, or switch to free play and scrub the loading yourself.

Mode

Story plays a prepared change and its fix. Free play is yours: every control snaps to an exported stop.

Story

Parabolic approximation, not a catenaryDraft, not an engineering sag-tension programGeometry: illustrativeGround-clearance verdict: demo logic, judged at hot and ice only

Profile · the conductor hangs between supports on the exported midspan elevations; tap a pole or a span to read its check

Plan · the same corridor from above

Gauges · section tension, midspan clearance against the requirement, net force at each insulator

Free play · scrub the loading, stretch the spans, raise the low pole

Check being read · click any row, pole or span

Actual

Required

Margin

How the harness read it

    Tension, ground clearance per span, insulator uplift per pole · the controlling row is highlighted

    The controlling row is the first failing check, else the first tight one; with none, the tension row is shown. The primary-over-underbuild check is a footer card below.

    Footer check · primary over a 4 ft underbuild at midspan

    Every check · before the change, after the change, after the fix

    A ground-clearance card reads "tight" when it passes with under 1.0 ft of margin; that band is a display choice, and the pass/tight/fail itself is the exporter's own logic (the harness has no midspan-to-ground function). Clearance is judged only at the hot (120 F) and ice (32 F) states; at the other three loadings it is a value with no verdict. Insulator uplift is the detect_insulator_uplift screen, not a code rule.

    Precomputed results:every verdict, required value and margin on this page was computed by the real Python harness at export time and is played back from a data file. The page runs no harness logic and holds no standards tables, and it never interpolates between exported values. Not a live API call. This is a PARABOLIC approximation (s = w L^2 / 8T with a ruling-span change of state), not a catenary, and it is not an engineering sag-tension program: the draft harness ports have no human subject-matter-expert sign-off. Every tension, ruling span, sag, clearance, net force and requirement was computed by calling the listed functions at export time (harness commit 16e0437) and is played back from a data file; free play only reads exported grid cells and snaps to their stops, it never interpolates. One conductor throughout: Linnet 336.4 kcmil ACSR 26/7, the harness's own test conductor, strung to 25% of its rated breaking strength at 60 F. The span lengths, pole heights, ground profile and what each span crosses are made up, and the vertical scale of the drawing is exaggerated (printed on it). The truck and walker are drawn to the vertical scale for reference only.Real functions this maps to:calculate_line_tension_solve, calculate_conductor_sag_tension_change_of_state, calculate_sag_check_temperatures, lookup_nesc_table232_1_clearance, compute_midspan_elevations, validate_span_clearance, detect_insulator_uplift.Not modeled: a catenary solution, creep and long-term elongation, ice-and-wind swing of the span in the real vertical plane, structure strength and deflection, insulator swing, line angles and multiple conductors, sag tables for other conductors, real site terrain and the NESC clearance states other than 120 F and 32 F ice, and any real line or design check.See also:Sag and tension, auto · Clearance (scripted sag, wire-to-wire) · Make-ready scenarios