Power factor measures the phase angle between the instantaneous voltage and the instantaneous current in a circuit.
Voltage (E) leads current (I) by 90° in an inductive (L) circuit
and voltage (E) lags current (I) by 90° in a capacitive (C) circuit.
A popular mnemonic is ELI the ICE man since E is leading (coming before) I in
ELI, and E is lagging (coming after) I in ICE.
power factor ( Pf ) = cos ( q ) |

|
Apparent Power ( P ) = I * V |
True Power = P |
I = Current |
q = Phase angle |
V = Voltage |
Power Formulas |
Apparent Power P = I * V P = I2
* R P = V2 / R
|
True Power P = I * V * cos (q) P
= I2 * Z * cos (q) P = V2 * cos (q) / Z P = Pa * Pf
|
Impedance Z = V2 * cos (q)
/ P Z = P / [I2 * cos (q)]
|
Current I = P / [V * cos (q)] I = sqrt {P
/ [Z * cos (q)]}
|
Voltage V = P / [I * cos (q)] V = sqrt [P
* Z / cos (q)]
|
|
where
|
P = power in Watts V = Voltage in Volts I = current in Amps R = resistance
in Ohms (Ω) Z = impedance in Ohms (Ω) q = phase angle between I and V in degrees Pa
= apparent power in Volt·Amps (VA) Pf = power factor |
|
|