Introduction:
Regulating the voltage in distribution feeders is essential to ensure a stable and reliable power supply. Various equipment options are available for this purpose, including static condensers, booster transformers, and tap changing transformers. It is important to consider the economic aspect when selecting the most suitable option.

Static Condenser:
Static condensers, also known as shunt capacitors, are used to improve the voltage profile in distribution feeders by compensating for reactive power. They are connected in parallel to the feeder and provide capacitive reactive power to counterbalance the inductive reactive power in the system. The main advantage of static condensers is their relatively low cost compared to other voltage regulating equipment.

Booster Transformer:
A booster transformer is used to regulate voltage by stepping up or stepping down the voltage level. It is connected in series with the feeder and can either increase or decrease the voltage along the distribution line. Booster transformers are typically more expensive than static condensers due to the additional complexity and materials required for voltage transformation.

Tap Changing Transformer:
Tap changing transformers, also known as on-load tap changers (OLTC), provide a means of adjusting the voltage levels in distribution feeders. They have multiple taps on the primary winding, allowing the voltage to be regulated by changing the tap position. Tap changing transformers offer precise voltage control and flexibility. However, they tend to be more expensive compared to static condensers and booster transformers due to their complex design and additional components.

Economic Considerations:
When considering the economic aspect, the most economical option for regulating voltage in distribution feeders would be the static condenser. Static condensers are generally less expensive in terms of initial investment and maintenance costs compared to booster transformers and tap changing transformers. They provide reactive power compensation at a relatively low cost and can effectively improve the voltage profile in the distribution system.

Conclusion:
In conclusion, the most economical equipment option for regulating voltage in distribution feeders would be a static condenser. While booster transformers and tap changing transformers offer additional functionalities and precise voltage control, they tend to be more expensive. The selection of the equipment should be based on a comprehensive analysis considering the technical requirements, cost-effectiveness, and long-term benefits of the specific distribution system.