Short Answer:

High-voltage transmission systems are designed to carry electricity over long distances with minimal losses. To achieve this, electricity is transmitted at different voltage levels depending on the distance, power capacity, and grid structure. Typical high-voltage transmission levels start from 66 kV and go up to 1200 kV in some advanced systems.

Common voltage levels include 66 kV, 110 kV, 132 kV, 220 kV, 400 kV, 765 kV, and in some countries like India and China, even 800 kV or 1200 kV for ultra high-voltage transmission. These voltage levels help in efficient power transfer and maintaining stability in large interconnected power networks.

Detailed Explanation:

Typical voltage levels used in high-voltage transmission

Definition of High-Voltage Transmission

High-voltage transmission refers to the movement of electricity through transmission lines at voltages higher than what is used in homes or industries. These systems are mainly used to carry large amounts of electricity from power generation plants to substations located closer to the consumption areas. High voltage is necessary because it reduces current in the lines, which in turn reduces power loss.

To ensure proper function, various standard voltage levels are used based on international and national standards, transmission distance, and power capacity.

Voltage Classifications in Transmission

Transmission voltage levels are usually grouped into categories:

High Voltage (HV) – 66 kV to 132 kV
- Used for regional power transmission
- Suitable for moderate distances
- Found in older networks and rural areas
Extra High Voltage (EHV) – 220 kV to 765 kV
- Widely used in national grids
- Carries large-scale electricity over hundreds of kilometers
- Used in major inter-state transmission lines
Ultra High Voltage (UHV) – 800 kV and above
- Used in very large countries like India and China
- Suitable for transmitting bulk power over extremely long distances
- Reduces the number of required transmission lines

Standard Voltage Levels Used

Some commonly used standard voltage levels in high-voltage transmission are:

66 kV – Entry level of high-voltage transmission
110 kV – Used in older networks and European systems
132 kV – Common in many countries for regional networks
220 kV – A base EHV level widely used in national grids
400 kV – Common backbone voltage for main grid transmission
500 kV – Used in specific countries for major bulk transfer
765 kV – Used in India for long-distance and high-capacity transmission
800 kV (DC or AC) – Used in UHV transmission for cross-country power flow
1200 kV – Emerging UHV level, tested in India for massive power movement

These voltage levels are determined based on factors like:

Distance of transmission
Power capacity required
Grid design and planning
Safety and insulation requirements

Why Different Voltage Levels Are Used

Short distances need lower voltage to reduce equipment cost.
Long distances need higher voltage to reduce power loss and improve efficiency.
High demand areas require higher voltage lines to supply the needed power.
Grid expansion plans often upgrade existing lines to higher voltages to handle more load.

In many power systems, voltage levels are chosen based on a balance between cost, performance, reliability, and energy efficiency.

Application Example in India

66 kV, 132 kV – Used for sub-transmission and local interconnection
220 kV, 400 kV – Common for state and inter-state bulk transmission
765 kV – Backbone of India’s National Grid
1200 kV – Developed by Power Grid Corporation for future UHV needs

Conclusion

Typical voltage levels used in high-voltage transmission range from 66 kV to as high as 1200 kV. These levels are selected based on the needs of the power system such as transmission distance, power volume, and system design. Higher voltages help reduce transmission losses, improve efficiency, and make long-distance bulk power transfer possible. Understanding these voltage levels is essential for managing and expanding modern power grids effectively.