Simple Answer:
Electrical power is transmitted at high voltages to reduce energy losses and improve efficiency during long-distance transmission. When electricity flows through transmission lines, some energy is lost as heat due to resistance in the wires. By increasing the voltage, the current decreases, which reduces these losses. High-voltage transmission also allows thinner conductors to be used, reducing material costs. Once the electricity reaches its destination, step-down transformers lower the voltage for safe use in homes and industries.
Detailed Explanation:
Electricity generated at power stations needs to be transmitted efficiently over long distances to cities, industries, and homes. If power were transmitted at low voltage, there would be huge energy losses due to the resistance of transmission wires. To prevent this, power is transmitted at high voltages, ensuring less energy loss, improved efficiency, and cost-effective transmission.
Reasons for High Voltage Transmission:
- Reduces Power Losses (I²R Losses):
- When electricity flows through wires, it faces resistance, which causes heat loss.
- Power loss in transmission lines is given by P = I²R, where I is current and R is resistance.
- By increasing the voltage (V), the current (I) decreases for the same power transmission, leading to less heat loss.
- Improves Transmission Efficiency:
- Lower power losses mean more electricity reaches consumers, making the system more efficient.
- High-voltage transmission ensures that less energy is wasted as heat, keeping electricity supply reliable.
- Reduces the Size and Cost of Conductors:
- Lower current means thinner wires can be used, reducing the amount of copper or aluminum needed.
- This lowers the construction and maintenance costs of power lines.
- Allows Long-Distance Transmission:
- High-voltage transmission is essential for sending power over hundreds of kilometers.
- If low voltage were used, more substations and booster stations would be needed, increasing costs.
- Easier Voltage Control and Step-Down for Distribution:
- At the receiving end, transformers step down the voltage to safe levels for homes and industries.
- High voltage ensures that the electricity remains stable during transmission and can be easily adjusted for different applications.
Example Calculation:
- Suppose a power plant generates 100 MW of electricity.
- If transmitted at 10 kV, the current would be very high, leading to large losses.
- If transmitted at 400 kV, the current would be much lower, reducing losses significantly.
Conclusion:
- Electrical power is transmitted at high voltages to minimize energy loss, improve efficiency, reduce transmission costs, and enable long-distance power delivery. By keeping the current low, high-voltage transmission helps in reducing heat losses, using thinner wires, and maintaining stable power supply. Once the power reaches its destination, transformers reduce the voltage to safe levels for household and industrial use.