✦ Short Answer:

High voltage reduces power loss in transmission lines by minimizing the current flowing through the conductors. When power is transmitted, the energy loss due to resistance in the wire is directly proportional to the square of the current. So, if current is high, losses are also high. By increasing the voltage, the current required to transmit the same power becomes low, which helps reduce energy loss significantly.

This method is extremely helpful in transmitting electricity over long distances. High-voltage transmission systems not only improve efficiency but also lower the cost of materials like conductors and reduce the number of transmission lines. This is why modern power grids rely on high-voltage lines to deliver power effectively and reliably.

Detailed Explanation:

How high voltage reduces power losses

❖ Understanding Power Loss in Transmission

Power loss in transmission lines is mainly due to the resistance of the wires through which the current flows. All conductors, like copper or aluminum, have some resistance. When electric current passes through these resistive wires, energy is converted into heat and lost.

This loss is known as I²R loss, where:

• I = current flowing through the wire
• R = resistance of the wire

So the power loss (P) = I² × R

If the current is high, the power loss becomes much larger.
If the current is low, the loss is much smaller.
This is the key principle behind using high voltage in power transmission.

❖ Relationship Between Power, Voltage, and Current

The total electrical power (P) being transmitted is calculated using the formula:
P = V × I
Where:

• P = Power (in watts)
• V = Voltage (in volts)
• I = Current (in amperes)

If the power P remains constant and voltage V is increased, then the current I will decrease.

Example:
To transmit 10,000 watts of power:

• At 100 V → Current = 100 A
• At 1000 V → Current = 10 A
• At 10,000 V → Current = 1 A

Now using the formula Power Loss = I² × R:

• At 100 A → Loss = 100² × R = 10,000 × R
• At 10 A → Loss = 100 × R
• At 1 A → Loss = 1 × R

This shows that transmitting at high voltage drastically reduces power loss.

❖ Advantages of Using High Voltage Transmission

1. Minimized I²R Losses
   Lower current leads to much smaller energy loss in the form of heat. This makes the system more energy-efficient.
2. Use of Thinner Conductors
   Since less current flows, the conductor size can be reduced. This lowers the cost of copper or aluminum wires and makes the towers lighter.
3. Improved Long-Distance Transmission
   High voltage allows electricity to be transmitted across hundreds of kilometers without significant drop in voltage or power loss.
4. Less Voltage Drop
   In high-voltage systems, the voltage drop due to line resistance is reduced, leading to stable voltage at the receiving end.
5. Lower Cost of Infrastructure
   Fewer and lighter transmission lines are required to carry the same amount of power, reducing the overall cost of towers and right-of-way land.
6. Better Load Handling
   High-voltage lines can carry more power, which is useful during peak demand or in high-load areas like cities and factories.

❖ Application in Modern Power Systems

High-voltage transmission is commonly used in:

• National power grids for moving bulk electricity
• Inter-state or inter-regional transmission lines
• Connecting power plants (hydro, thermal, nuclear) to distant cities
• Renewable energy systems where wind or solar farms are located far from urban areas

Typically, electricity is generated at 11–25 kV, then stepped up to 132 kV, 220 kV, 400 kV, or even 765 kV using transformers for transmission. It is then stepped down near cities for safe distribution.

❖ Why Not Use Low Voltage for Long Distances?

If electricity were transmitted at low voltage (like 230 V or 400 V), the current needed to deliver large amounts of power would be huge. This would:

• Cause massive power losses
• Require thick and expensive conductors
• Generate excessive heat
• Make the system unsafe and uneconomical

Hence, high voltage is the only practical solution for long-distance energy transmission.

✦ Conclusion

Transmitting electricity at high voltage is a smart and essential technique to reduce power loss in transmission lines. Since power loss depends on the square of the current, increasing voltage and reducing current makes the system more efficient and cost-effective. This method is used worldwide to ensure that power generated at faraway stations can be delivered safely and reliably to cities, industries, and homes. Without high-voltage transmission, large-scale power distribution would not be possible in modern electric systems.