Understanding the Basics

Before buying a generator, it’s essential to grasp the difference between kilowatts (kW), kilovolt-amperes (kVA), and amps. kW measures real power—what actually performs work—while kVA measures apparent power, which includes both usable power and reactive power in the system. The relationship between them is dictated by the power factor (PF), usually between 0.8 and 1.0 for most generators.

Key Conversion Formulas

The basic formula for single-phase systems is:
kW = (Volts × Amps × Power Factor) ÷ 1,000
For three-phase systems:
kW = (Volts × Amps × √3 × Power Factor) ÷ 1,000
To go from kW to kVA, divide by the power factor. For example, a 10 kW load with a PF of 0.8 equals 12.5 kVA. A handy conversion chart or amp calculator can speed up these calculations.

Why Power Factor Matters

Generators are rated in kVA, but most appliances are rated in kW. Knowing the power factor ensures you size your generator correctly so it can handle both the real and reactive components of the load without overloading.

Quick Reference Table

For a single-phase system at 240V and PF of 0.8:
– 5 kW ≈ 6.25 kVA ≈ 26 amps
– 10 kW ≈ 12.5 kVA ≈ 52 amps
– 20 kW ≈ 25 kVA ≈ 104 amps
For quick lookups, keep a laminated electrical reference guide in your toolkit.

Practical Buying Tip

When comparing generators, match your load requirements in kW to the generator’s kVA rating, adjusting for the power factor. This ensures your unit won’t struggle under load and will operate efficiently.