A capacitor bank is used for power factor correction in electrical systems to improve power factor and increase the efficiency of the system. Power factor is the ratio of real power (active power) to apparent power in an AC circuit. A low power factor indicates that a significant portion of the supplied power is being wasted as reactive power, which results in increased line losses and reduced efficiency.
Capacitor banks are designed to offset the reactive power drawn by inductive loads (such as motors, transformers, and fluorescent lighting) and reduce the reactive power demand from the utility. By adding capacitors to the system, the power factor can be brought closer to unity (1.0), which is the ideal power factor.
Here's how a capacitor bank works for power factor correction:
Capacitor Bank Installation: The capacitor bank consists of multiple individual capacitors connected in parallel or series-parallel configuration. These capacitors are usually rated to handle high voltages and currents, depending on the power system requirements.
Reactive Power Compensation: Inductive loads consume reactive power, leading to lagging power factor (usually denoted as "cos φ"). The capacitor bank, when connected in parallel with these inductive loads, produces reactive power in the form of capacitive reactive power, which compensates for the reactive power demand of the inductive loads.
Reducing Reactive Power Flow: When the capacitor bank is operational, it reduces the flow of reactive power from the power source (e.g., the utility) because the reactive power generated by the capacitors cancels out the reactive power drawn by the inductive loads. This results in a reduced overall reactive power demand, leading to a higher power factor.
Improved Power Factor: As the reactive power demand is minimized, the power factor improves, moving closer to unity (1.0). A power factor closer to 1.0 means that a higher percentage of the supplied power is utilized for useful work, and there are fewer losses in the system.
Benefits of Power Factor Correction: Power factor correction using capacitor banks offers several advantages, including:
Reduced electricity costs: Improved power factor means reduced penalties for low power factor charges from utilities.
Increased system efficiency: Lower losses in the transmission and distribution system.
Enhanced equipment performance: Lower reactive power flow leads to less stress on electrical equipment, resulting in longer lifespans and improved reliability.
Optimal utilization of power resources: A more efficient use of the available power supply.
It's important to note that while a capacitor bank can be used to correct a low power factor, caution must be exercised to avoid overcompensation, which could result in a leading power factor. A leading power factor can be as undesirable as a lagging power factor and may cause other operational issues in the electrical system. Proper engineering and monitoring of the system are necessary to ensure the capacitor bank's effective and safe operation for power factor correction.