Power factor is a measure of the efficiency of power utilization in alternating current (AC) circuits. It indicates the ratio of the real power (in watts) to the apparent power (in volt-amperes) in the circuit. In simpler terms, it quantifies how effectively the current flowing through a circuit is being converted into useful work.
Mathematically, power factor (PF) is defined as the cosine of the angle (θ) between the voltage (V) and current (I) waveforms in an AC circuit:
Power Factor (PF)
=
cos
Power Factor (PF)=cosθ
Where:
θ (theta) is the phase angle between voltage and current waveforms.
PF ranges between 0 and 1, where 0 represents a purely reactive circuit (all power is reactive, no real power), and 1 represents a purely resistive circuit (no reactive power, all power is real).
Power factor can also be calculated using the following formulas, based on other parameters:
Power Factor (
PF
PF) = Real Power (
P) / Apparent Power (
S)
PF
=
PF=
S
P
Power Factor (
PF
PF) = Resistance (
R) / Impedance (
Z)
PF
=
PF=
Z
R
A power factor of 1 (or close to 1) indicates that the current and voltage waveforms are in phase, and the circuit is effectively utilizing the power. A power factor less than 1 indicates the presence of reactive components (inductive or capacitive elements) that lead to a phase shift between voltage and current waveforms. In such cases, the apparent power is greater than the real power, resulting in inefficient use of power.
Improving power factor is important in many practical applications to minimize losses, increase efficiency, and reduce the load on power distribution systems. This is often achieved by adding power factor correction devices such as capacitors or inductors to compensate for the reactive power and bring the power factor closer to 1.