what is meant by the term “ Power Factor Correction”. Using a phasor diagram

Power Factor Correction (PFC) is a technique used in electrical systems to improve the power factor of the system. Power factor is the ratio of real power (measured in watts) to apparent power (measured in volt-amperes). It is a measure of how effectively the electrical power is being used. A power factor of 1 indicates that all the power is being used effectively, while a power factor less than 1 indicates that some power is being wasted.

In an AC circuit, power factor correction is used to change the phase angle between the current and voltage waveforms, bringing them into alignment so that all the power supplied by the source is used to do useful work.

Here's a step-by-step explanation using a phasor diagram:

1. Draw a phasor diagram with voltage as the reference phasor. The current phasor can be leading (for capacitive load) or lagging (for inductive load) with respect to the voltage phasor.

2. The angle between the voltage and current phasor represents the phase difference between them. This phase difference is the cause of a power factor less than 1.

3. Power factor correction involves adding a reactive component (capacitor or inductor) to the circuit to counteract the effect of the existing reactive component (inductor or capacitor). This changes the phase of the current waveform, bringing it into alignment with the voltage waveform.

4. In the phasor diagram, this is represented by the current phasor rotating towards the voltage phasor, reducing the angle between them. When the current and voltage phasors are aligned (i.e., the angle between them is zero), the power factor is 1, indicating that all the power is being used effectively.

5. The amount of reactive power (measured in VARs) added or subtracted by the power factor correction component can be represented by a phasor perpendicular to the real power phasor (which is along the voltage phasor). The length of this reactive power phasor represents the amount of reactive power.

6. After power factor correction, the total power (apparent power) phasor is the vector sum of the real power and reactive power phasors. This apparent power phasor is now aligned with the voltage phasor, indicating a power factor of 1.