Motor Starting kVA Estimator
Sizing a generator for motor-starting demand: estimate locked-rotor kVA from motor HP and the NEMA code letter, factor in the starting method (across-the-line, soft start, or VFD), and read out a minimum genset kW capability.
- Locked-rotor kVA
- 298kVA
- Required starting kVA
- 595kVA
- Min. genset capability
- 99kW
- Suggested standby kW
- 100kW
Estimate uses NEMA code letter mid-band kVA/HP. Actual locked-rotor current and required genset starting kVA depend on motor design class, load profile, and the genset alternator's subtransient reactance (X″d). For mission-critical motor starting, request the manufacturer's starting-kVA curve and confirm voltage dip ≤ 15%.
Need a motor-starting simulation?
For mission-critical installations we run formal motor-starting simulations using the alternator's published X″d and saturation curves.