High voltage and low current are used in transmission lines to minimize power losses. Here's how it works.
1. Power Equation:
Power transmaitted over a line is given by \( P = VI \), where \( P \) is power, \( V \) is voltage, and \( I \) is current.
2. Resistance Losses:
Power loss due to the resistance \( R \) of the transmission line is given by \( P_{loss} = I^2 R \). This means power loss is proportional to the square of the current.
3. High Voltage, Low Current:
By increasing the voltage and decreasing the current for a given power, the resistive losses \( I^2 R \) are significantly reduced because the current is lower.
For example, if the voltage is doubled, the current can be halved to transmit the same power, reducing the power loss to one-fourth.
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| Transmission lines |
why transmission lines operate at high voltages,
often in the range of hundreds of kilovolts.
Transmission lines create high voltage and low current through the use of transformers. Here's the process in detail:
1. Generation:
Electricity is generated at power plants at a lower voltage, typically between 11 kV and 25 kV.
2. Step-Up Transformers:
The generated electricity is then sent through step-up transformers, which increase the voltage to much higher levels, often between 100 kV and 765 kV.
3. Transmission:
The high-voltage electricity is transmitted over long distances through transmission lines. At these high voltages, the current is lower for a given power, reducing resistive losses.
4. Step-Down Transformers:
Near the point of use, the high-voltage electricity is passed through step-down transformers, which decrease the voltage to safer, more usable levels for homes and businesses, typically down to 110-240 volts.
The use of transformers at both ends of the transmission line allows for efficient long-distance transmission of electrical power with minimal losses.
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