Real, Reactive & Apparent Power Explained
Electrical power in AC circuits comes in three related forms: real power, reactive power, and apparent power. Together they explain why a circuit can draw more current than its useful power output alone would suggest.
Real power
Real power (measured in watts) is the power that actually does useful work, such as turning a motor shaft or producing light and heat.
Reactive power
Reactive power (measured in VAR) is the power that oscillates between the source and inductive or capacitive loads without doing useful work. It still requires current to be delivered, even though no work results.
Apparent power
Apparent power (measured in VA) is the total power delivered by the source, combining real and reactive power. It is what determines the actual current draw on a circuit.
How they connect
Real, reactive, and apparent power form a right triangle, with apparent power as the hypotenuse. Power factor is the ratio of real power to apparent power, and ties this whole relationship together.