What is a capacitor bank and why is it used?

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Capacitors (or capacitor banks) are used to improve the operational efficiency of electric power systems and to help transmission and distribution system voltage stability during disturbances and high load conditions.

• Capacitors are used to cancel the current effects of motors and transformers.
• The capacitor can reduce system losses and provide voltage support.
• Another advantage of capacitors is that they can reduce the total current flowing through a wire and thus leave capacitance in conductors for additional loads.
• Capacitor banks can be continuously left online to meet the steady-state reactive power requirements of the system or they can be switched on or off to meet the dynamic reactive requirements.

There are two types of reactive power compensation in a power system - series and shunt.

In distribution compensation, shunt compensation can be installed near the load, along with distribution feeders or in transmission substations. 

Each application has a different purpose.

• Shunt reactive compensation can be inductive or capacitive.
• At the load level, at distribution substations and with distribution feeders, compensation is usually capacitive.
• In a transmission substation, both inductive snd capacitive reactive compensation is used.
• Capacitor banks are installed on the distribution line to reduce losses, improve voltage support and provide additional load capacity on the distribution system. Reducing the loss of distribution system with capacitors is very effective as it also reduces the loss of transmission.

The closer a capacitor is installed to the actual inductive load itself, the more advantageous it is. For example, if capacitors are properly installed at motor terminals in industrial loads, the losses in the lines feeding the motor are minimized, the distribution losses will be minimized, the transmission losses will be minimized and the generation losses Will also be reduced.