Generator Sizing Calculator – kVA Generator Selection Tool

Generator Sizing Calculator

kVA Generator Selection Tool for Engineers

Load Power:

kW kVA

Power Factor (PF):

Motor Load Percentage (%):

Motor Starting Method: DOL (×3) Star-Delta (×2) Soft Starter (×1.5) VFD (×1.2)

Future Expansion Margin (%):

Total Connected Load: -- kVA

Motor Starting Impact: -- kVA

Applied Safety Margin: --%

Recommended Generator Size: -- kVA

Nearest Standard Generator Rating: -- kVA

Formulas Used

1. Convert to kVA: If input kW: kVA = kW / PF. If kVA: use directly.
2. Motor Starting Additional kVA: Load kVA × (Motor % / 100) × (Starting Factor - 1)
3. Total before margin: Load kVA + Additional kVA
4. Final Recommended: Total × (1 + Margin / 100)
5. Standard Rating: Round up to nearest standard generator size from common ratings.

Practical Notes

• Generator sizing must consider motor starting current.
• Always keep margin for future load expansion.
• Final generator selection should be verified with manufacturer data.
• Consult a qualified electrical engineer for site-specific applications.
• Consider altitude, temperature, and harmonic loads for precise sizing.