In electricity, power is the rate electrical energy sent/consumed in a circuit, the basic concept in electrical engineering, measured in Watts (W), with 3 types: apparent power (S), reactive power (Q), and true power (P).
[6] True/Real/Active power (P) is the power that does useful work.
Apparent power (S) is the total power supplied to the circuit, a combination of true and reactive power, measured in VA.
Reactive/Wattless power (Q) oscillates back and forth between a source and load, not doing useful work, measured in VARs, consumed in AC circuits, not doing useful works but are crucial on phase shift between voltage and current waveforms. They're linked to the reactance made by inductors and capacitors and counteracts real power's effect and don't exist in DC circuits.
AC
The power triangle is the bond between P, Q, and S, drawn as a right triangle: S = √(Q² + P²).
Power triangle's concept is mainly used in the AC circuits, which the voltage and current aren't always in phase, giving existence to reactive power and real power.
[2] Power factor measures how efficiently an electrical system uses power, the P to S.
A high power factor tells a system uses electricity effectively, with less power wasted.
PF = 1 → Pure resistive load (no power is reactive and all real)
PF < 1 → Inductive (lagging) or capacitive (leading) load
Power factor is improved by:
Add capacitors (for inductive loads like motors).
Use synchronous condensers.
Avoid lightly loaded motors.
E.g. A factory of 0.7 PF with capacitors added improving it to 0.95, reducing energy bills.
[1] Wikipedia
[2] What is power factor? How to Calculate Power Factor Formula - Fluke
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