Apparent, active, and reactive power (PQS)

Apparent power (S) is the capacity of your measured power system to provide active (real power, P) and reactive power (Q).

A typical AC electrical system load has both resistive and reactive (inductive or capacitive) components. Resistive loads consume real power (P). Reactive power (Q) is either consumed (inductive loads) or generated (capacitive loads).

Standard	PF sign	Description
IEEE	+	Leading power factor
	-	Lagging power factor
IEC	+	Positive active energy
	-	Negative active energy

The units for power are watts (W or kW) for real power P, vars (VAR or kVAR) for reactive power Q, and volt-amps (VA or kVA) for apparent power S.

Positive real power P(+) flows from source to load, and negative real power P(-) flows from the load to the power source.