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The National Grid

The National Grid

The National Grid

In the U.K., electricity is distributed across the country by the national grid. This makes use of step up and step down transformers in order to efficiently meet the high demand of power.

What is the national grid?

Pick all the options you think are part of the national grid.

You can select multiple answers

What do we call the electricity produced by power stations?

What do we call the electricity required by homes?


This is a simplistic overview of the national grid.

It shows how the electric power is transported from the power station to people's homes via cables and transformers.

We need to transmit a high amount of electrical power to meet the demand of UK households. Remember that P=VIP=VI. What does that tell us about the value of either VV or II?

Is electricity transferred at high or low voltage from power stations to our homes?

We transport electricity at high potential difference (or voltage) VV and low current II. Why do you think we do that?

To meet the high power demand, we need either high potential difference or high current because P=VIP=VI. The problem with trying to use a high current is that it creates a lot of heat loss, so we would lose lots of valuable energy. So instead, we boost potential difference to a really high value - 400,000 V! This means we can use a low current.

Does the electricity that enters our homes have a potential difference of 400,000 V?

In order to distribute power across the nation, power stations transfer it at high voltages of up to 400,000 volts. However, it does not enter our home at this voltage. Instead we reduce it to 230 volts before it enters our homes.

So we need to increase the potential difference to 400,000 V before we transport it from the power stations and we need to reduce it to 230 V before it enters our homes. To do that, we use...

Step up transformers increase the potential difference to around 400 kV before it is sent from the power station. Step down transformers reduce the potential difference to a safe level of 230 V for us to use in our homes.