How many kVA of generator is needed? (Sizing)
Approximate generator power S(kVA) = P × simultaneity × (1 + margin) / cosφ This is determined by... For example, for a total load of 200 kW, 0.8 simultaneity, margin and cosφ 0.8, approximately 240 kVA is required. The motor starting current should also be evaluated.
S(kVA) = P × simultaneity × (1 + margin) / cosφ
Example calculation: 200 kW total load, simultaneity 0.8, margin , cosφ 0.8 → S = 160 × 1.2 / 0.8 = 240 kVA; rounded to the nearest upper standard type.
Generator Sizing (kVA)
Calculate the approximate generator power (kVA) based on total load, power factor, simultaneity, and spare margin.
Suggested power
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Effective load (kW)
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Notes: S(kVA) = P × simultaneity × (1 + margin) / cosφ. This vehicle does not include engine starting (starting) current. — For large, directly driven motors, instantaneous demand generation is very demanding and requires separate evaluation. UPS/critical loads and future growth must also be considered.
How is it calculated?
- Enter the total active load (kW).
- Enter the power factor, concurrency, and spare margin.
- Press Calculate; the recommended kVA will be displayed.
Frequently Asked Questions
What should the generator's VA capacity be?
S is calculated as S = P·simultaneity·(1+margin)/cosφ; the result is rounded to the nearest higher standard type.
Why is motor starting current important?
Large motors, when started directly, draw multiples of their rated current at startup; the generator must be controlled separately to meet this instantaneous demand.
Why is a reserve margin left?
A margin of around is typically left to account for future load increases, efficiency loss, and safe operation.
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