Convert Apparent Power from Kilovolt-Amperes (kVA) to other units

What is a Kilovolt-Ampere (kVA)?

A Kilovolt-Ampere (kVA) is a unit of measurement for "apparent power."

Apparent power represents the total amount of power being used in an electrical circuit. One kVA is equal to 1,000 volt-amperes.

Think of it as the complete power load, which is why kVA is the most important measurement for correctly sizing heavy-duty electrical equipment.

Apparent power (kVA) is a combination of two distinct types of power:

1. Real Power (kW): This is the "useful" power that performs the actual work, like lighting a bulb or turning a motor.
2. Reactive Power (kVAR): This is the power required by equipment like motors and transformers to create a magnetic field, which is necessary for their operation.

How to Calculate kVA

You can calculate kVA using a simple formula.

For a single-phase circuit, which is common in most homes and small businesses, the kVA formula is:

kVA = (Voltage × Amperes) / 1000

For example, a 240-volt circuit drawing 50 amps would have an apparent power of 12 kVA.

(240 Volts × 50 Amps) / 1000 = 12 kVA

Why kVA Matters: Sizing Generators and UPS Systems

This is the most crucial part: Key equipment like generators, transformers, and Uninterruptible Power Supplies (UPS) are all rated in kVA.

This kVA rating tells you the true maximum load the equipment can safely handle.

If you only look at the real power (kW) when sizing a generator or UPS, you risk choosing a unit that is too small.

An undersized unit can overload, overheat, or fail when you need it most.

The kVA rating provides the complete power picture, ensuring your equipment can handle both the "useful" (kW) and "wasted" (kVAR) power safely.