Evidence

Sources and model boundaries

Reviewed 29 July 2026. Links lead to publishers/manufacturers; edition and local adoption must be confirmed by the responsible professional.

• IEC 60364-5-52 — wiring-system selection and voltage-drop context. Restricted tables are not reproduced.
• IEC 60947-4-1:2023 — current standards-publisher scope for electromechanical contactors and motor starters.
• ABB Contactors and Overload Relays Guide — IEC 60947-4-1 context and manufacturer selection boundaries.
• Schneider Electric TeSys Giga star-delta guidance — requires three-phase, six accessible terminals, matching delta/main voltage and a load suitable for reduced starting torque.
• Siemens SIRIUS contactor assemblies manual — transition wiring and switchover current-peak considerations.
• Schneider Electric Motor Data Calculator FAQ — approximate motor-data tool scope.
• Schneider Electric VFD motor cable guidance — cable capacitance and drive-specific selection considerations.
• Schneider Electric ATV320 cable-length FAQ — product-specific output-filter and shielded-cable guidance.

Formula basis

Input power is converted to estimated line current using efficiency and power factor. Resistance-only voltage drop uses ρL/A at a 75°C planning temperature. Three-phase drop uses √3IR; single-phase uses 2IR. Reactance is omitted. The cable shortlist uses an openly disclosed current-density proxy, not a jurisdictional ampacity table.

Star-delta boundary

Ideal balanced star starting reduces winding voltage, line current and starting torque compared with DOL. Published fractions describe ideal-condition relationships, not guaranteed field results. This tool avoids an exact universal performance claim and blocks star-delta unless every mandatory eligibility answer is confirmed.

A 400Δ/690Y motor may be delta-run on a 400 V supply; a 230Δ/400Y motor must not be treated as delta-rated for a 400 V supply. Transition timing, residual voltage, current peaks and mechanical effects require professional review.

Do not infer

A passing screen does not establish cable compliance, protection coordination, fault withstand, safe disconnection, EMC performance, enclosure temperature or suitability for installation.