Size the electrical supply that feeds a motor — full-load and starting current for an AC/VFD drive with the real power factor and efficiency losses, or DC battery runtime with Peukert derating and a safe depth-of-discharge margin.
A VFD corrects input power factor near unity regardless of motor PF, cutting supply current.
NEC/IEC size feeders at 125% of motor FLA.
Input from shaft. Nameplate power is shaft output; electrical input is P_in = P_shaft / η. The difference is heat in the motor.
Current. Three-phase full-load current I = P_in / (√3 · V · PF) (single-phase drops the √3). Apparent power S = P_in / PF in kVA is what the utility meters and often bills, so a poor PF costs money even though it does no work — Q = √(S²−P²) is the reactive part.
VFD effect. At the motor, current depends on mechanical load, not the supply method — a VFD doesn't cut full-load motor current. But on the input side a VFD's rectifier presents a near-unity power factor (~0.98), so the current drawn from the mains is lower than a motor connected direct-on-line at 0.86 PF.
Starting. Inrush is a multiple of FLA set by the starting method: 6–8× DOL, ~3× star-delta, 2–3× soft starter, 1–1.5× VFD. This governs breaker and contactor selection and voltage-dip at start.
Conductors. Codes size motor feeders at 125% of FLA for continuous duty. Final protection must follow NEC 430 / IEC 60364 and the nameplate.