A shunt reactor is a device used in electrical power systems to control reactive power. Reactive power is the component of power that oscillates between sources and loads due to the presence of reactive elements like inductors and capacitors in the system. Power factor correction involves managing the ratio of real power (active power) to apparent power in an electrical system.
Shunt reactors are primarily used to compensate for excessive capacitive reactive power in a power system. When there are long transmission lines, underground cables, or heavily loaded cables in the system, they can introduce capacitance, which tends to lead to a high voltage and low current condition. This results in a leading power factor, which is not desirable in many situations.
A leading power factor can cause several issues, including over-voltage conditions, reduced efficiency of generators and transformers, and increased line losses. To counteract this leading power factor, shunt reactors are connected in parallel to the system. Shunt reactors are essentially inductive devices that consume reactive power, which in turn reduces the net capacitive reactive power in the system. This has the effect of moving the power factor towards unity (1.0) or slightly lagging (as most practical systems are inductive to some extent).
In summary, a shunt reactor affects power factor correction by consuming reactive power and countering the excessive capacitive reactive power in the system. It shifts the power factor away from being too leading (capacitive) towards a more balanced or slightly lagging (inductive) condition. This helps improve the efficiency and stability of the power system by reducing over-voltage conditions and other associated issues caused by a leading power factor.