Power factor correction refers to the process of improving the power factor of an electrical system to bring it closer to unity (1 or 100%). It involves reducing the phase difference between voltage and current, which is caused by inductive loads like motors, transformers, and fluorescent lighting. These loads consume reactive power, leading to a lagging power factor. By adding components like capacitors, synchronous condensers, or phase advancers, reactive power is compensated, and the power factor is improved.

In practical terms, power factor correction aims to minimize the inefficiencies in the electrical system, reduce energy losses, and ensure optimal utilization of the power supplied by the generator or grid.

• By improving power factor, the current flow in the system is reduced, leading to lower I²R losses in cables, transformers, and other distribution components.
• With a higher power factor, the electrical system operates more efficiently, ensuring better utilization of the generated power.
• Improved power factor reduces the apparent power (kVA) requirement, allowing for smaller-sized generators, transformers, and cables, thus reducing capital costs.
• Higher power factor ensures better voltage stability across the system, preventing voltage drops and protecting sensitive equipment from under-voltage issues.
• By reducing reactive power, the system can handle more active power (real load) within the same capacity of the equipment, maximising output.
• With reduced current and heat generation, the wear and tear on electrical components are minimized, extending their lifespan.
• Higher efficiency in power usage reduces the overall energy demand, lowering fuel consumption and greenhouse gas emissions in power generation.

A three-phase system typically has an inductive load (e.g., motors), causing a lagging power factor. Capacitors can provide leading reactive power to compensate for this. The capacitors are connected in parallel with the inductive load.

• The size (capacitance) of each capacitor is calculated based on the size of the inductive load and the desired power factor improvement. Specialised software or calculation methods are often used for accurate determination.
• The capacitors are connected in a star or delta configuration, matching the load's connection. They should be appropriately rated for the voltage and current of the system.
• The leading reactive power supplied by the capacitors cancels out some of the lagging reactive power from the inductive load, effectively reducing the overall reactive power and improving the power factor.

Besides capacitors, synchronous motors can also be used for power factor correction. Synchronous motors can be operated at leading power factor, effectively counteracting the lagging power factor of inductive loads. These motors can contribute both real power and leading reactive power to the system. However, synchronous motors are more complex and expensive than capacitors. They are often used in larger industrial installations where the power factor correction requirements are significant.