Engineering guide
kW vs kVA on a UPS: output power factor by manufacturer
A UPS's kVA rating is apparent power; its kW rating is the real power it delivers, and the ratio is the output power factor. On a unity model kW equals kVA: XPC states it for the M90U-80, and Delta rates the Ultron DPS-300K at 300 kVA / 300 kW. On a 0.9 model, 30 kVA gives 27 kW, as on Tripp Lite's SVTX. Size on the kW your load draws, then check the kVA.
Key facts
- XPC M90U-80: unity power factor, kW = kVA
- Delta Ultron DPS-300K: 300 kVA / 300 kW
- Tripp Lite SVTX 30 kVA model: 30 kVA / 27 kW
- ABB SG Series: 1.0 from 10 to 40 kVA, 0.9 from 60 to 600 kVA (IEC)
- ABB Conceptpower DPA: output power factor 0.8 (IEC)
The one formula
kW = kVA × output power factor. kVA is the apparent power the UPS output is rated for; kW is the real power it can deliver to the load. With a unity output power factor, the two are equal. With 0.9, a 30 kVA UPS delivers 27 kW, which is exactly how Tripp Lite rates its 30 kVA SVTX. With 0.8, a 50 kVA module delivers 40 kW.
Output power factor by family
| Family | As the manufacturer states it | kW per kVA |
|---|---|---|
| XPC M90U-80 | Unity PF (kW = kVA) | 1.0 |
| Delta Ultron DPS | DPS-300K: 300 kVA / 300 kW | 1.0 |
| Mitsubishi 9900B | unity power factor output | 1.0 |
| Tripp Lite SmartOnline SVX | unity (1,0) output power factor | 1.0 |
| Tripp Lite SmartOnline SUTX | 20 kVA / 20 kW and 40 kVA / 40 kW | 1.0 |
| Tripp Lite SmartOnline SVTX | 10 kVA / 9 kW, 20 kVA / 18 kW, 30 kVA / 27 kW | 0.9 |
| ABB SG Series (IEC) | 1.0 from 10 to 40 kVA, 0.9 from 60 to 600 kVA | 1.0 or 0.9 |
| ABB Conceptpower DPA (IEC) | output rated PF 0.8 | 0.8 |
Ratings as published by each manufacturer; IEC versions are noted where the North American model may differ.
Size on kW, then check kVA
- Measure the real load in kW at its peak, from the PDUs, the existing UPS display or a power meter.
- Compare it with the kW rating of the new UPS, not only its kVA.
- Check the kVA as well when the load power factor is low.
- Leave headroom for growth and for redundancy: with one module or one unit out, the rest must still carry the load.
Replacing an older UPS
A like-for-like kVA replacement can hide a kW change. Tripp Lite puts it plainly for the SVX: because it is rated at unity power factor, it may be sized for actual power and load requirements. When an older 0.8 power factor unit is replaced by a unity model of the same kVA, the new one delivers more kW; when the new model is 0.8, the kW must be checked against the measured load.
Getting the sizing done
Load studies and system selection are part of our sizing and installation consultations, and a first estimate can be worked out with the step-by-step sizing guide. For the full method, see sizing a three-phase UPS.
Related pages
Common questions
What is the difference between kW and kVA on a UPS?
kVA is the apparent power rating; kW is the real power the UPS can deliver. kW = kVA × output power factor.
How many kW is a 30 kVA UPS?
It depends on the output power factor: 30 kW at unity, 27 kW at 0.9 (Tripp Lite rates its 30 kVA SVTX at 27 kW), 24 kW at 0.8.
Should I size a UPS in kW or kVA?
In kW first, from the measured peak load, then check the kVA, and leave headroom for growth and redundancy.
Why does a new UPS of the same kVA carry more load than the old one?
Older units were often rated below unity power factor. A unity model of the same kVA delivers more kW; Tripp Lite notes that a unity-rated SVX may be sized for actual power.
Do all three-phase UPS have unity power factor?
No. Among published ratings, XPC's M90U-80, Delta's Ultron DPS and Mitsubishi's 9900B are unity, Tripp Lite's SVTX is 0.9, and ABB's IEC Conceptpower DPA is 0.8.
Sources, checked October 4, 2026:
- Xtreme Power Conversion, M90U-80 product page
- Delta, Ultron DPS technical specifications
- Tripp Lite, SmartOnline 3-phase UPS systems brochure, pp. 7, 9
- Tripp Lite, SmartOnline SVX 3-phase UPS system brochure, p. 5
- ABB, SG Series IEC product page
- ABB, Conceptpower DPA technical data
- Mitsubishi Electric, 9900B UPS product page
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