If you've ever wondered why genset catalogs always list capacity in kVA — not kW like most electrical equipment — you're not alone. This confusion is very common, and it often leads to choosing a genset with the wrong capacity.

What Is kW (Kilowatt)?

kW, or kilowatt, is the unit of real power — the power actually converted into useful work. This is what's printed on your equipment's nameplate: a 2 kW AC unit, a 1.5 kW pump, a 3 kW welding machine. It's also what's calculated on your utility electricity bill.

What Is kVA (Kilovolt-Ampere)?

kVA is the unit of apparent power — the total power generated by the genset and flowing through the cables, including the reactive component that does no real work. The genset must be able to supply this full kVA, regardless of how much the load actually uses.

The Relationship Between the Two: Power Factor

Power Factor (PF) is the ratio between kW and kVA, with a value between 0 and 1. Industrial gensets are generally designed around a PF of 0.8. This means a 10 kVA genset can only supply 8 kW of real power at any given moment.

kW = kVA × Power Factor

Three Power Factor Ranges You Should Know

• PF 0.95–1.0: Purely resistive loads — incandescent lamps, heaters, irons. Almost all power becomes real work.
• PF 0.8–0.9: Typical mixed loads — a combination of small motors, lighting, and electronic equipment.
• PF 0.5–0.7: Heavy inductive loads — large unloaded motors, welding equipment, old-style ballasts.

A Practical Calculation Example

Total real power requirement of 8 kW, estimated Power Factor of 0.8:

kVA = 8 kW ÷ 0.8 = 10 kVA
With a 25% safety margin: 10 × 1.25 = 12.5 kVA minimum

Practical Tips

• Always use kVA for genset sizing, not kW directly.
• If you're unsure about the PF, assume 0.8 to stay safe.
• Add a 20–25% buffer above your calculated requirement.
• For non-linear loads (UPS, inverters, VFDs), consider a PF lower than 0.8.

Use the Jerbindo load simulator to automatically calculate your kVA requirement based on your equipment list.