# Power Factor Improvement

If the power factor is low or poor, it is necessary to improve or correct it. It may be improved by injecting a leading current into the circuit so as to neutralize the effect of lagging current. The power factor may be improved by using static capacitors or synchronous motors.

### Power factor correction by static capacitors

Consider an inductive load consisting of a resistor R and an inductor L connected to an AC supply. The circuit and phasor diagrams are shown in the figure.

V – supply voltage.

I_{1} – load current

φ_{1} – phase angle by which the current I_{1} lags behind the voltage

cosφ1 – original power factor

Let the capacitor C be placed in parallel with the load. It will take a leading current I_{c } from the supply. The circuit and phasor diagrams are shown in the figure.

The total I_{2} drawn from the supply will be equal to the phasor sum of I_{1} and I_{c} that is

### Conclusions

- The phase angle of I
_{2}is φ_{2}. It is seen from the phasor diagram that the φ_{2 }is less than φ_{1}, and hence, cosφ_{2}is greater than cosφ_{1}. In other words, the power is improved from cosφ_{1}to cosφ_{2}. - The new current supply from the supply is less than the load current I
_{1}, i.e., I_{2}> I_{1}. The new current is given by the equation

- By connecting a capacitor in parallel with an inductive load, the power factor is improved, and the current from the supply is reduced without altering either current or power taken by the load.

This relation shows that the power taken from the supply has not altered.