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Motor Starting Current & Volt-Dip

Motor full-load and starting current per starting method, with the transient volt-dip on the supply cable checked against a dip limit

Rated power

Nameplate mechanical output

Supply voltage

Line-to-line, three-phase

Efficiency (η)

Power factor (run)

cos φ

Method

Starting multiplier

× FLC

~6–8× FLC (Siemens: 7–8× typical)

Starting power factor

cos φ

Near locked-rotor: typically 0.1–0.3 (0.2 if unknown)

Cable mV/A/m (resistive)

mV/A/m

BS 7671 App 4 r column; the single figure for ≤ 16 mm²

Cable preset (BS 7671 abridged)

Single-phase values auto-scaled ×0.866 for 3φ. Verify against actual cable data.

Cable mV/A/m (reactive)

mV/A/m

0 for ≤ 16 mm²; App 4 x column for ≥ 25 mm²

One-way length

Max dip during start

Enter motor rating, efficiency and power factors (ratios in 0–1)