Real Power: The actual power in Watts or K-Watts in AC or DC Circuits Apparent power: The Power in Inductive or Capacitive Circuits have Phase Lag & Lead measured in Volt Amperes VA or Kilo Volt Amperes KVA
Real power (P) or active power[1]: watt [W]
Reactive power (Q): volt-ampere reactive [var]
Complex power (S): volt-ampere [VA]
Apparent Power (|S|), that is, the absolute value of complex power S: volt-ampere [VA]
Phase of Voltage Relative to Current (φ), the angle of difference (in degrees) between voltage and current; Current lagging Voltage (Quadrant I Vector), Current leading voltage (Quadrant IV Vector)
All definitions start from the impedance triangle, composed of R, X, and Z. The apparent power, also called complex power, is the phasor sum of the real power and the reactive power. It's calculated by I²Z.
Real power is the energy rate dissipated by the resistive part of the impedance triangle. It's calculated by I²R.
Reactive power is the rate of energy stored and retrieved from the reactive components of the impedance triangle. That energy is not dissipated, but instead returned back to the circuit. It's calculated by I²X.
Average power is the total electrical energy moved over a time period divided by the time period.