Alternating current and the National Grid
The National Grid
The The network that connects all of the power stations in the country to make sure that everywhere has access to electricity. distributes electricity across the country. The National Grid connects power stations to homes, workplaces and public buildings all around the country through a system of cables and transformers. The electricity may be produced by a conventional power station turning a Device that converts kinetic energy into electrical energy..
Learn more on the National Grid in this podcast
Listen to the full series on 大象传媒 Sounds.
Transformers
Transformers are used to change voltages and
As the power transferred must stay the same:
- increasing voltage decreases current
- decreasing voltage increases current
In the National Grid, a A transformer that increases the voltage of the ac supply. is used to increase the voltage and reduce the current. Less current means less energy is lost through heating the wire which is the main reason for using transformers. The voltage is increased from about 25,000 Volts (V) to 400,000 V causing the current to decrease.
To keep people safe from these high voltage wires, pylons are used to support transmission lines above the ground.
Before reaching the end user, a A transformer that decreases the voltage of the ac supply., reduces the voltage from the transmission voltage to the safer voltage of 230 V for home use.
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