Power Factor or True Power Factor (PF or TPF) is the value which takes into account the presence of higher harmonics. For sinusoidal systems, it is equal to the Displacement Power Factor (DPF). Hence, DPF is a measurement of the phase shift between the fundamental voltage and current components.
In case of a purely resistive load (in a one-phase system), the apparent power is equal to active power (in terms of value), and reactive power equals zero, so such a load fully uses the energy potential of the source and the power factor is 1.
Appearance of a reactive component inevitably leads to the reduction of energy transmission effectiveness with the active power then being less than apparent power, and an increase in reactive power.
In three phase systems, the power factor reduction is also influenced by an unbalance load. In such systems, correct power factor value is obtained using the effective measurement of apparent power (Se).