ABOUT PF:


Power factor is usually angle between the voltage sine wave and the current sine wave. For details to know, it is the efficiency of electricity consumption. Same as the efficiency of a machine.
Actually, it is the ratio of KW to KVA.

Power Factor(COSφ) = KW/KVA.

But, it is not the only power factor present in the power system. It's depend on which value of voltage and current we consider, there are different power factor available-


  1. Displacement Power Factor: - The power factor which due to the phase shift between voltage and current at the fundamental frequency is known as Distortion Power Factor.                                                Displacement PF = P/ V1I1.
  2. Distortion Power Factor: - The power factor which includes the effect of harmonics present in the system is called Distortion Power Factor.                                                                                                      Distortion PF = 1/ √1+%iTHD²
  3. True Power Factor:- It is the ratio of average power and apparent power. Above two power factors also combine together to form the True Power Factor.   i.e. True Power Factor = Displacement PF x Distortion PF.                                                                                                                         True PF = P/ Vrms Irms.

When we want power factor correction by means of installation of capacitors, we are referring to improvement of only the displacement power factor, which improves the True PF. Capacitor act as a alternate source of kvar and and decrease the inductiveness in the system, and  capacitor also reduce the lagging between the current and voltages. The result is improve the power factor.
  But it is important to know that this voltage and current wave form is respect to the fundamental frequency i.e. 50 Hz. There may be some cases where even after installing capacitors at site, but power factor does not improve.

Here a new power factor comes i.e. Distortion PF.
Under normal condition , KVA = KW/PF. (here the system current is  the rms current i.e. 50 Hz.)
For pure sinusoidal cases (i.e. without harmonics)

True PF = Distortion PF = COSφ.

Where, φ is the angle between voltage and current wave.
Suppose, In case of  our system is run with non-linear loads, when our system is polluted by harmonics and rms current is also increases.- 
Formula - I = I1 √1+iTHD².