Your Factory Has a 210 kW Load. Why Isn’t a 210 kVA Transformer the Answer?

Illustrative screening example: kVA depends on power factor. Standard size selection still requires the actual project conditions.

The intuitive answer is often wrong

A factory totals its operating load at about 210 kW. The buyer says, “Then we need roughly a 210 kVA transformer.”

The sentence sounds logical because the two numbers look similar. But kW and kVA describe different things, and treating them as interchangeable can push the RFQ in the wrong direction before anyone compares suppliers.

The line to remember

kW is real power. kVA is apparent power. Transformers are rated in kVA, not by copying the kW total from a load list.

Why power factor changes the number

For a first-pass AC load screen, the relationship is commonly written as kVA ≈ kW ÷ power factor. If the real load is 210 kW and the average power factor is 0.80, the apparent power is about 262.5 kVA. At a lower power factor, the required apparent power is higher again.

That is why two factories with the same 210 kW real load may not lead to the same transformer kVA decision.

The formula is not the design

The next questions matter just as much: Is 210 kW the sum of all nameplates or the actual peak demand? Are large motors involved? Is the load cyclic? Are new production lines planned? Are UPS, VFD, or rectifier loads significant? Are the phases reasonably balanced?

The formula is useful because it prevents one obvious mistake. It does not replace system engineering.

Do not hide uncertainty inside a giant margin

Once buyers realize kW and kVA are different, a common reaction is to add a large safety factor and move on. That can hide the real reason the number is uncertain. Low power factor, motor starting, future expansion, and nonlinear loads are different problems. They should be described, not buried inside one arbitrary percentage.

What TransformerGrid asks for

• average and peak load
• power factor
• simultaneous loads
• largest single load
• motor starting method
• future expansion
• primary/secondary voltage and phase configuration

Turn the load list into a usable RFQ

If all you have is an equipment power list—or even a rough “total kW” number—send it to TransformerGrid. We can help organize the missing questions so the manufacturing review starts from a better data set.

Do not copy kW into the kVA box. Understand the load first, then decide what capacity range deserves engineering review.