Theory
What is True Power?
The actual amount of power being used, or dissipated, in a circuit is called true power, and it is measured in watts (symbolized by the capital letter P, as always).
What is Reactive Power?
We know that reactive loads such as inductors and capacitors dissipate zero power, yet the fact that they drop voltage and draw current gives the deceptive impression that they actually do dissipate power.
This “phantom power” is called reactive power, and it is measured in a unit called Volt-Amps-Reactive (VAR), rather than watts.
The mathematical symbol for reactive power is (unfortunately) the capital letter Q.
What is Apparent Power?
The combination of reactive power and true power is called apparent power, and it is the product of a circuit’s voltage and current, without reference to phase angle.
Apparent power is measured in the unit of Volt-Amps (VA) and is symbolized by the capital letter S.
The Power Triangle
