kVA
2. kVA
kVA stands for kilovolt-amperes. It represents the apparent power in an electrical circuit. Apparent power is the vector sum of real power (kW) and reactive power (kVAR). Think of apparent power as the total volume of liquid in your mug, including both the beer (kW) and the foam (kVAR). You’re paying for the whole mug, even if you’re only really drinking the beer. Reactive power isn’t “consumed” in the same way as real power. Instead, it circulates in the circuit, flowing back and forth without doing any useful work.
This reactive power is usually associated with inductive loads, such as motors, transformers, and large fluorescent lighting systems. These devices need a magnetic field to operate, and creating that magnetic field requires reactive power. In a purely resistive load (like a heater), all the power is real power (kW), and kVA = kW. But in a load with reactive components, kVA will always be higher than kW.
Why does this difference matter? Because electrical equipment — generators, transformers, and wiring — needs to be sized to handle the total apparent power (kVA), not just the real power (kW). Even though the reactive power isn’t doing useful work, it still puts a strain on the electrical system. It increases the current flowing through the wires, which can lead to overheating, voltage drops, and reduced equipment lifespan.
Consider an office building with many computers and air conditioners. These devices have reactive components. If the electrical system is only sized based on the kW demand, it might be overloaded by the higher kVA demand, leading to problems.