The National Grid
The National Grid distributes electricity across the country. It connects power stations to homes, workplaces and public buildings all over the country. The electricity may be produced by a conventional power station turning a generator or by another method such as wind turbines or solar panels.
The national grid uses step-up and step-down transformers to change the voltage and current. A transformer consists of coils of wire coiled around an iron core. The number of coils will determine whether the transformer is step up or step down.
The power that is transferred through the lines must stay the same, hence if the voltage increases then the current decreases and if the voltage decreases then the current increases.
In the national grid, a step-up transformer is used to increase the voltage (around 25,000 Volts (V) up to 400,000 V) This increase of voltage decreases the current, A lower current will result in less energy is lost due to heat, making it more efficient. The transmission lines are suspended in the air by big pylons to keep people safe from the high voltage wires. Before reaching our homes a step-down transformer is used to lower the voltage to 230 V which is safe for use at home.