High voltage and low current are used in power lines to reduce energy losses. Here's how it works.
1. Power Equation:
The energy sent through a line is calculated using the formula P = VI, where P's the energy V is the voltage and I is the current.
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2. Resistance Losses:
The energy lost due to the resistance of the power line is calculated using the formula P loss = I squared R. This means that the energy lost increases rapidly with the current.
3. High Voltage, Low Current:
By raising the voltage and lowering the current for a given energy the energy lost is significantly reduced because the current is lower.
For example if the voltage is doubled the current can be halved to send the energy reducing the energy lost to one quarter.
Power lines work at high voltages often hundreds of thousands of volts which is why they use high voltage.
Power lines use devices called transformers to create high voltage and low current. Here's the process:
1. Generation:
Electricity is made at power plants at a voltage of around 11,000 to 25,000 volts.
2. Step-Up Transformers:
The electricity is then sent through step-up transformers, which increase the voltage to higher levels often between 100,000 and 765,000 volts.
3. Transmission:
The high-voltage electricity is sent over distances through power lines. At these voltages the current is lower for a given energy reducing energy losses.
4. Step-Down Transformers:
Near where the electricity's needed the high-voltage electricity is passed through step-down transformers, which decrease the voltage to safer levels for homes and businesses usually down to 110-240 volts.
Using transformers at both ends of the power line allows for long-distance transmission of electricity with losses. This is why power lines use voltage and low current. Power lines rely on voltage and low current to minimize energy losses. High voltage and low current are crucial, for electricity transmission.
