How to size a data center generator
Work in kW first. Convert to kVA only after the real load is in the number. Then pick N+1 or 2N and derate for the site.
Start with IT load in kW. Multiply by PUE so cooling is in the number — often 1.4 to 1.8. Add house loads. Add 20–25% for growth, UPS step load, and harmonics. Apply N+1 or 2N, then derate for heat and altitude. Send that list. We return a sized natural gas or LPG option, not a diesel catalog pick.
Five numbers we actually use
01
IT load in kW
Nameplate IT, not a guess from rack count. If you only have kVA, say so. We will not pretend it is kW.
02
Multiply by PUE
Cooling has to transfer with the IT load. A genset that covers servers and leaves the chillers dark still takes the hall down. 1.4–1.8 is common if you have not measured.
03
Add house loads
Lighting, security, BMS, other mechanical. Small on a big hall. Not small on an edge node.
04
Add 20–25% margin
Growth, UPS step load, and harmonics. Going tighter than 20% only makes sense if the load list is measured and locked.
05
N+1 or 2N, then site derate
N is the count that carries the load. N+1 adds a spare for service or a fail-to-start. 2N is a full duplicate plant. Then knock the rating down for high ambient and altitude.
Worked example
400 kW IT, PUE 1.5, 80 kW house, 25% margin, N+1 on 350 kW gas units.
This is a sketch, not a one-line. Altitude, ambient, and UPS step load still move the answer.
What to send for a factory quote
A spreadsheet is enough. We do not need a 40-page RFP to size a gas or LPG set.
- IT kW, or a rack/load list.
- PUE or chiller kW if you have it.
- Natural gas or LPG, and whether this is standby or bridge.
- N+1 or 2N.
- Site high ambient and altitude, if known.
Sizing questions that show up on RFQs
If the load list is rough, say so. We would rather size with a margin than invent precision. Send a load list →
kW first. kVA depends on power factor. We convert after the real load is in the sheet.
1.4–1.8 for a first pass. Send chiller kW instead if that is what you have.
N units carry the load. N+1 adds one spare. 2N duplicates the whole plant. We parallel gas sets for either layout.
Yes. A one-line or a load list is enough for a first factory option.
Get your data center generator quote
Tell us IT kW, cooling or PUE if you have it, natural gas or LPG, N+1 or 2N, and whether this is standby or bridge power. Engineers usually reply within one business day with sizing and a spec outline.