The purpose of a Power Factor Correction Capacitor (PFC capacitor) is to improve the power factor of an electrical system. Power factor is a measure of how efficiently electrical power is being utilized in a circuit. A low power factor indicates that the circuit is drawing more reactive power (non-useful power that oscillates between source and load) relative to the useful or active power (power that performs useful work).
When an electrical load is inductive (e.g., electric motors, transformers, fluorescent lights), it causes a phase difference between the voltage and current waveforms, resulting in a lagging power factor. This leads to higher reactive power consumption and lower overall system efficiency. Reactive power does not contribute to useful work but still flows through the electrical system, causing additional losses and putting strain on the power distribution infrastructure.
By adding a Power Factor Correction Capacitor to the circuit, it compensates for the lagging reactive power drawn by inductive loads. The capacitor supplies reactive power, which cancels out the reactive power drawn by the inductive load. This results in a near-zero reactive power flow, hence improving the power factor close to unity (1.0).
The benefits of power factor correction using capacitors include:
Improved efficiency: By reducing the reactive power flow, power factor correction capacitors help minimize losses in the electrical system. This, in turn, increases the overall efficiency of the system, as less power is wasted.
Reduced electricity bills: Many electricity suppliers charge consumers based on their power factor. A poor power factor means higher apparent power (combination of active and reactive power), and consumers may face penalties or higher charges for low power factor. Implementing power factor correction can lead to cost savings by avoiding such penalties.
Increased electrical system capacity: When the power factor is improved, the electrical system's apparent power is reduced, allowing more actual useful power to be transmitted through the existing infrastructure. This can postpone the need for infrastructure upgrades and potentially save on capital expenditures.
Reduced voltage drop: Power factor correction can help mitigate voltage drops in the electrical distribution system, which can lead to improved performance of sensitive equipment and motors.
In summary, power factor correction capacitors improve the efficiency of electrical systems by reducing reactive power, which in turn leads to lower losses, reduced electricity bills, and improved capacity utilization of the existing infrastructure.