Alternating Current

P=\frac{1}{2}V_pI_pcos\theta=V_{rms}I_{rms}cos\theta

File:Cmplxpower.svg

$P$ $P$
- Active Power
  - Real Power
- Watt (W)
$Q$ $Q$
- Reactive Power
- Volt-ampere reactive (VAR)
$S$ $S$
- Complex Power
- Volt-ampere (VA)
$|S|$ $∣ S ∣$
- Apparent Power
- Volt-ampere (VA)
$\varphi$ $φ$
- Phase of voltage relative to current
- $\varphi=arg(V)-arg(I)$
- Current lagging voltage (quadrant I vector)
- Current leading voltage (quadrant IV vector)

Power Factor

Ratio of real power to apparent power

Lower PF have higher circulating current
- Energy back to source from load storage
- Higher losses