Power Factor Formula For Single Phase

Power factor is only related to the AC circuit.DC circuit will not have power face since there is zero frequency and phase angle difference between current and voltage.

Power Factor is given by the cosine of the angle between voltage and current

P =VI Cosθ

Rearranging the above formula we get

Cosθ =P/VI


Cosθ = True Power/Apparent Power


Cosθ = Power factor

P = Power in Watts

V = Voltages in Volts

I = Current in Amperes

The true power is given in terms of Watts and the Apparent power is given in terms of Volt-Amperes or Watts

The power factor in an AC circuit is also given by the ratio of Resistance and Impedance

Cosθ =R/Z


R = Resistance in ohms

Z = Impedance

Impedance (Z) is the total resistance in the AC circuit and is given by



R = resistance

X=inductive reactance

Xc = capacitive reactance

Here, it is noted that single-phase power factor is less than 1.

Note: For a purely resistive circuit, the power factor is 1.

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