What is power factor correction and what are two common methods to achieve it?

What is power factor correction and what are two common methods to achieve it?

• A. Passive shunt capacitors/inductors and active PF correction using power-electronic controllers
• B. Series resistors and inductors
• C. Only by increasing voltage
• D. Using transformers

Answer: (C)

Power factor correction is about reducing reactive power so the current waveform stays in closer step with the voltage, making energy use more efficient. When a load is inductive, the current lags the voltage and draws more reactive power, lowering the power factor. The goal of correction is to lessen that lag and reduce unnecessary circulating current, so a larger portion of the apparent power does real work. Two common ways to achieve this are: first, passive shunt PF correction, which adds capacitors in parallel with the load to supply reactive current locally and cancel part of the inductive reactance. This brings the overall current closer to in-phase with the voltage and raises the power factor. Second, active PF correction, which uses power-electronic controllers to shape the input current waveform so it follows the voltage more closely, often achieving near-unity PF and reducing harmonic distortion. Increasing voltage does not fix the phase relationship or the reactive power; it changes magnitudes but not the fundamental lag between current and voltage. Relying on series components or transformers alone doesn’t correct the overall power factor.

Power factor correction is about reducing reactive power so the current waveform stays in closer step with the voltage, making energy use more efficient. When a load is inductive, the current lags the voltage and draws more reactive power, lowering the power factor. The goal of correction is to lessen that lag and reduce unnecessary circulating current, so a larger portion of the apparent power does real work.

Two common ways to achieve this are: first, passive shunt PF correction, which adds capacitors in parallel with the load to supply reactive current locally and cancel part of the inductive reactance. This brings the overall current closer to in-phase with the voltage and raises the power factor. Second, active PF correction, which uses power-electronic controllers to shape the input current waveform so it follows the voltage more closely, often achieving near-unity PF and reducing harmonic distortion.

Increasing voltage does not fix the phase relationship or the reactive power; it changes magnitudes but not the fundamental lag between current and voltage. Relying on series components or transformers alone doesn’t correct the overall power factor.