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National Grid Physics

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National Grid Physics

You have probably interacted with the national grid in some way or another in order for you to read this article. The grid exists to get electricity from where it is generated to where it is needed or required, so you probably used the national grid to charge your phone this morning, or it's even powering the computer that you are using right now! We're going to discuss what is involved within the national grid, as well as how it works to transport massive amounts of electricity across the country.

What is the meaning of the national grid?

All of the electricity in the country has to be generated somewhere, which is usually within power plants around the country. The main way this electricity gets from power stations to users is via the national grid.

The national grid is a nationwide system of power stations, power lines, transformers, and electricity users within the United Kingdom.

The vast majority of the electricity in the national grid is transferred via overhead transmission cables, where the current must be kept low in order to have minimal energy loss to heat within the wires.

What does the national grid system do?

The national grid isn't just a web of connections all over the country. It is also important for making sure that electricity production keeps up with demand. You see, the amount of electricity being used changes throughout the day, as people wake up, go to work and come home. The operators of the national grid can predict when large amounts of electricity are going to be required, and adjust the amount of electricity being produced and transported accordingly.

Most of the time, power plants are running at below their maximum operating capacity, and can therefore generate a lot more electricity when the national grid demands it. Several smaller power stations are kept in a standby state that can be spun up relatively quickly if the demand is even higher than the standard power plants can supply.

Remember: electricity production must meet electricity demand.

What are some features of the national grid?

The most obvious and widely observed features of the national grid are the overhead cables, called powerlines, that span the British countryside, like the one shown below. There are a few different types of overhead cabling that you will see around the UK, but not all of them carry electricity. The easiest way to tell if an overhead cable is carrying electricity is by listening for the constant buzz that they make as you get closer to the pylons.

National grid an image of overhead power cables in Kent united kingdom StudySmarterA typical overhead powerline in Kent, Wikimedia Commons CC BY-SA 2.0.

As well as these overhead transmission cables, the national grid is made up of buildings called transformers. There are two types of transformers within the national grid: step-up transformers and step-down transformers. A step-up transformer takes the electricity generated by a power station and prepares it for transmission across the country by increasing the voltage, whereas a step-down transformer takes electricity from overhead wires and makes it usable by consumers by decreasing the voltage. The buildings that house these transformers are often called substations, and electricity can flow through any number of substations between the power plant and the user of the electricity.

National grid an image of an electrical substation in minnesota United States StudySmarterA typical electrical substation, Wikimedia Commons.

But what is that buzzing sound coming from above? That sound is created by a phenomenon called corona discharge. Corona discharge is a process in which the air around the powerline allows little lightning bolts to travel through it whenever the voltage is high, which happens a lot of times every second because powerlines carry alternating current (AC). This means that the buzzing that you hear from powerlines is actually a lot of mini lightning bolts happening super fast one after the other!

A diagram of the national grid

To help you to understand how the national grid works, there is a simple diagram below that shows you what the national grid does, and the order from electricity producer to consumer. Summarised, we have the following.

  1. Electricity (electrical power) is produced in a power station.
  2. A step-up transformer increases the voltage such that the same amount of power can be transported with a smaller current, decreasing the energy losses to heat.
  3. The power lines transport the electricity from place to place.
  4. A step-down transformer decreases the voltage to a much lower value such that households can safely use the electricity provided.
  5. Households receive the low-voltage electricity.

A black and white diagram showcasing the order of objects within the national grid, from power producer all the way to electricity consumer.A simplified version of the national grid, StudySmarter Originals.

Electricity transfer methods in the national grid

So, we've already discussed what hardware makes up the national grid. Now, let's discuss how electricity gets around. The national grid system aims to get electricity to consumers with as little waste heat as possible. Waste heat is bad for an electricity transmission system, as it cuts the efficiency and decreases the amount of electricity getting from the producers to the consumers. The easiest way to reduce the amount of energy lost to heat is to decrease the amount of heat generated by transmission via overhead cables!

The best way to reduce this heat is by reducing the current within the overhead and long-distance transmission cables. The national grid uses an extremely high potential difference alongside a very low current. This does, however, keep the amount of power travelling through the cables the same, thanks to the power equation

,

whereis power,is voltage, andis current. A step-up transformer takes the voltage of the power plant (which is around) as an input, and outputs electricity at a voltage of about, with a current of about. At the other end of the power network, where a consumer would like to use this electricity, the voltage needs to be returned to a safer level, at about. A step-down transformer is used to convertto, after which the electricity is distributed to a large number of consumers in the area. This ensures that the national grid is an efficient way of transferring electricity across the country.

National Grid Physics - Key takeaways

  • The national grid is a web of power cables and substations across the country that distributes electricity from power stations to consumers in an efficient way.
  • The main features of the national grid are large overhead power cables and small substations, that consist of transformers.
  • The role of transformers in the national grid is to step the voltage up for efficient cross country transmission of electricity through powerlines and then to step that voltage back down so that the electricity is safe for a consumer to use.
  • The power equationplays a vital role in understanding how the transformers in the national grid work.
  • The operating voltage of the overhead transmission cables in the national grid is around, and the mains voltage in households is around.

Frequently Asked Questions about National Grid Physics

The national grid is a nationwide system of power stations, power lines, transformers, and electricity users within the United Kingdom.

The national grid works by connecting power stations to consumers through power lines, thereby transferring electricity from supply to demand.

Step-up transformers are used in the national grid to increase the voltage coming out of a power station so that the transmission of electricity across a large distance is efficient. 

The main features of the national grid, besides power stations, are massive electrical transmission cables and substations that act as transformers.

The national grid transfers electricity via overhead cables. These overhead cables carry a voltage of around 400 000 volts and transfer electrical power by allowing a current to flow through them.

Final National Grid Physics Quiz

Question

What is the national grid system?

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Answer

The national grid is a system of power stations, power lines, transformers, and electricity users that serves the United Kingdom.

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Question

How is electricity transmitted by the national grid?

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Answer

Overhead powerlines

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What is the mains voltage in the UK?

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Answer

230 V.

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What does the national grid do?

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Answer

The national grid transports electricity from producer to consumer. It also manages power production in the United Kingdom to ensure that production always meets or exceeds demand.

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What is the operating voltage in the powerlines of the national grid?

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Answer

400,000 V.

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How does the national grid minimise the amount of energy lost to heat in an overhead transmission cable?

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Answer

By using a high voltage, overhead cables can use a very low current, minimising the amount of waste heat energy.

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Question

What does a step-up transformer do in the national grid?

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Answer

It increases the voltage leaving a power station.

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Why would we want to use a step-up transformer in the national grid?

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Answer

To reduce the amount of energy wasted as heat.

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What does a step-down transformer do in the national grid?

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Answer

It decreases the voltage from the overhead transmission cables.

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Why would we want to use a step-down transformer in the national grid?

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Answer

To make sure that the electricity reaching consumers' houses is safe.

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What is the type of current used by the national grid?

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Answer

AC (Alternating Current).

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If cables transmit a certain fixed amount of electrical power, and we double the voltage, what happens to the current?

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Answer

The current will halve.

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What do the 'up' and 'down' in 'step-up' and 'step-down' transformers refer to?

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Answer

The voltage.

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Question

Generally speaking, what is the voltage of electricity leaving a power station?

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Answer

25,000 V.

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