A 100 kVA UPS can supply 80 kW at a load power factor of 0.8, provided its rated kW output is at least 80 kW. UPS output PF is rated kW ÷ rated kVA, and the datasheet decides the rest: output PF range, operating limits and derating. IEC 62040-3 Edition 3.0 writes the performance classification as a code, and the code implies no topology.
Four ideas to carry into the next specification conversation you have.
A UPS cannot exceed its kVA rating, and cannot exceed its rated kW. UPS output PF means rated kW ÷ rated kVA from the datasheet. A 100 kVA unit on a 0.8 power-factor load can supply 80 kW, provided its rated kW output is at least 80 kW: the kVA limit binds. The same unit at 0.9 output PF on a unity load gives 90 kW, because the kW limit binds. Each of the nine combinations is the lower of the two limits: at output PF 0.8, 0.9 and 1.0 the results are 80/80/80, 80/90/90 and 80/90/100 kW (load PF 0.8, 0.9, 1.0).
Foreword item c of IEC 62040-3 Edition 3.0:2021 says the performance classification coding was shortened from eight to seven characters. Classes 1, 2 and 3 are dynamic output performance classes (Figures 2 to 4 of the standard).
Clause 5.3.4 is titled performance classification: the code describes performance and implies no topology (standby, line-interactive or online double-conversion). Ask the bidder to state the IEC 62040-3 performance code for the offered unit.
Simplified educational calculation: a 0.80 ageing factor means the aged battery must still meet the duty, so the target divides by 0.80. A 15 min target becomes 15 ÷ 0.80 = 18.75 min for a new battery, a 25% margin. The battery itself is sized from the maker's constant-power or watts-per-cell data at the required autonomy, temperature, discharge rate and end-of-discharge voltage.
From the Foreword of IEC 62040-3:2021, Edition 3.0 (items c, f and g). Check which edition an offer cites, and whether it is the 2021 text.
| Item | What the 2021 text says | Source |
|---|---|---|
| Classification code | seven characters, down from eight | Foreword, item c |
| Non-linear step load | no longer a type test | Foreword, item c |
| Non-linear load, Annex E | requirements relaxed | Foreword, item f |
| Annex I efficiency | minimum values became normative | Foreword, item g |
| Performance classes | Class 1, 2 and 3 (dynamic output performance) | Figures 2 to 4 |
| Classification basis | performance classification | clause 5.3.4, title |
| UPS output power factor | rated kW ÷ rated kVA, from the datasheet | each model's datasheet |
| Leading and lagging limits | model-specific: read the datasheet | each model's datasheet |
Five steps that turn a kVA number into a working system.
Sum the real power of the load, then size so the result clears both the kVA and the kW limit at the load's actual power factor. Some IT power supplies use active power factor correction, one way to meet the harmonic limits of IEC 61000-3-2.
Leading and lagging limits are model-specific, so read them from the datasheet. This chart is the arithmetic ceiling only, and assumes nothing about the curve shape. The kVA rating is the constant; kW is what moves.
Every kilowatt a UPS wastes must also be removed by the cooling plant. Assumed: 500 kW continuous output, 8,760 h a year, cooling COP 3. Calculated at 0.32 SAR/kWh: going from 94% to 99% efficiency saves about 100,000 SAR a year, a quarter of it heat removal that a loss-only comparison leaves out. At 100 kW, about 20,000 SAR. SERA commercial tariff above 6,000 kWh a month: 32 halalas per kWh (SERA, updated 18 March 2026); used here as an illustration, use the project tariff.
Dividing by 0.80 is a simplified educational calculation of the margin, not a runtime equivalence. Size the battery from the maker's constant-power or watts-per-cell data at the required autonomy, temperature, discharge rate and end-of-discharge voltage.
In this example, the shared static bypass, one battery string and one distribution path stay single. Name which level the redundancy is at, and check what is still single downstream of it.
These three settings set the usable rating and the battery you buy. NLC default, not an external rating: the code is the IEC 62040-3 performance classification code the offer must state. The output power factor sets how many kW the UPS delivers at its rated kVA. The ageing factor sets how much battery you buy.
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