What do you know about capacitor banks used in substations?

 Why capacitor bank is used in substations?

A capacitor bank is a group of capacitors that are connected in series or parallel to provide reactive power compensation and power factor correction in a substation. 

Capacitor banks are used for several reasons, such as:- 

• Improving the quality and efficiency of the electrical supply by reducing losses, voltage drops, and harmonics (Harmonics Mitigation).

• Increasing the capacity of the system by allowing more load to be connected without overloading the transformers or cables (Line Loss Reduction).

• Reducing the cost of electricity by avoiding penalties for low power factor or reactive power demand (Reactive Power Support).

• Enhancing the stability and reliability of the system by supporting voltage regulation and reducing the risk of voltage collapse (Electrical Stability).

• Protecting the equipment from damage due to overvoltage or overheating caused by excessive reactive power.

• Capacitor banks are usually installed at specific points in the system, such as substations or feeders, where they can provide the optimal amount of reactive power compensation for the load or network conditions.

Capacitor banks can be shunt-connected, which means they are in parallel with the load, or series-connected, which means they are in series with the transmission line. Shunt / parallel capacitor banks are more common and are used to cancel out or reduce the lagging reactive power caused by inductive loads, such as motors, transformers, etc. Series capacitor banks are used to reduce the impedance of long transmission lines and increase their power transfer capability.

Power Triangle and Formulas

How do capacitors work in power factor correction?

Capacitors are used in power factor correction because they help to improve the power factor by relieving the supply line of the reactive power. The capacitor achieves this by storing the magnetic reversal energy. Power factor correction uses parallel connected capacitors to oppose the effects of inductive elements and reduce the phase shift between the voltage and current. This technique uses capacitors to reduce the reactive power component of an AC circuit in order to improve its efficiency and reduce current.

What are the safety precautions when replacing a capacitor bank in a substation?

Power Disconnection:

Ensure the capacitor bank's power supply is disconnected.
Lock out and tag all associated circuit breakers to prevent accidental re-energization.

Grounding:

Verify that the capacitor bank and associated equipment are properly grounded.

Dissipate stored electrical energy to minimize the risk of electric shocks.

Personal Protective Equipment (PPE):

Provide personnel with insulated gloves, safety glasses, and protective clothing.

Ensure all workers wear appropriate PPE to guard against electrical hazards.

Testing and Discharge:

Verify that the capacitors are fully discharged using suitable testing equipment.

Safely dissipate any remaining electrical energy in the capacitors using discharge devices.

Work Permits and Procedures:

Adhere to established work permit protocols and procedural guidelines.

Conduct the replacement work in a controlled and supervised manner.

Emergency Response Plan:

Have a well-defined emergency response plan in place.

Include protocols for addressing electrical faults, fires, or other safety hazards.

Qualified Personnel:

Assign the replacement work to trained and experienced personnel.

Ensure the team has a comprehensive understanding of electrical safety procedures.

Equipment Inspection:

Thoroughly inspect all replacement equipment, tools, and components.

Verify the integrity and functionality of all items before commencing work.

Following these step-by-step safety precautions will create a secure work environment and reduce the potential hazards associated with replacing capacitor banks in substations.

Thank you for the learning
UBApepi team.