Electricity - 2.4.3 The National Grid (GCSE Physics AQA)
The National Grid
Transporting Electrical Energy
The National Grid
- Electrical energy can be transported. Electricity is produces in power stations, but is used in other buildings, such as homes, offices and supermarkets. In other words, we have to find a way to transport the electrical power from the power stations to the consumers.
- The UK National Grid transports electricity. The UK National Grid is able to transport the electrical energy from power stations to consumers. It does this by using a system of cables and transformers.
Efficient Energy Transfers
Transformers
- Electrical energy transfers should be efficient. When transporting so much electricity across the country, there is a huge risk of energy waste because the power is so high. Therefore, the National Grid needs to make the transfer of electrical energy as efficient as possible. To do this, the National Grid makes use of transformers.
- Transformers change the voltage of a circuit. Transformers used electromagnetic induction to change the voltage of a circuit – they either increase it (step-up transformers) or decrease it (step-down transformers). The National Grid has very high powers, meaning very high currents and voltages. During transport, we can boost the voltage very high and make the current very low, but still maintain the same power.
- Step-up transformers are used at the start. As soon as electricity leaves the power station, a step-up transformer increases the voltage. As resistance is constant, current falls to a very low level (V=IR). When the current is low, we are able to reduce the energy losses via heat.
Study Mind Tip: The voltage during transfer is above 300,000V, which is much higher than the 230V in homes. This is why pylons and wires tend to have ‘Danger – High Voltage’ signs on them. - Step-down transformers are used at the end. When the electricity reaches the place of use, a step-down transformer decreases the voltage and thus increases the current (since resistance is constant). The electricity can now be used in homes, offices and any other domestic use. The current is high enough to give us a good energy supply.
Mechanism of Transformers
Later in the section ‘Magnetism’, we will learn that a changing electric current can induce a magnetic field, and vice versa. The principle is called electromagnetic induction.
Transformers use electromagnetic induction to change the voltage of a circuit – either increase it (step-up transformers) or decrease it (step-down transformers).
If an alternating current passes through a coil of wire, a changing magnetic field is produced. If you place a second coil of wire nearby, the changing magnetic field will induce a new alternating current in this second coil. This is how a transformer works,
Transformers only work for alternating current, because you need a changing magnetic field.
The size of the induced voltage depends on the number of turns on each coil – if there are less in the secondary coil, the voltage falls, and if there are more in the secondary coil, the voltage rises.
The National Grid is a system of power plants, transmission lines, and substations that deliver electricity to homes and businesses all across the country. It’s kind of like a big network of pipes and wires that work together to bring electricity to you!
The National Grid is run by a company called National Grid plc, which is responsible for making sure that the electricity supply is always flowing to where it needs to go. They work closely with other companies and organizations to make sure everything runs smoothly.
The National Grid works by transmitting electricity from power plants to substations, which then distribute the electricity to homes and businesses through local transmission lines. When you turn on your lights or use any electrical device, the electricity travels through these lines to get to you.
A substation is a facility that takes in high-voltage electricity from transmission lines and transforms it into lower-voltage electricity that can be used by homes and businesses. The lower-voltage electricity is then sent out to homes and businesses through local distribution lines.
We need the National Grid because electricity can’t be stored easily. When you turn on your lights, you need electricity right away, so it has to be generated and delivered to you as quickly as possible. The National Grid makes this possible by transmitting electricity over long distances and ensuring that the electricity supply is always available where it’s needed.
A power plant is a facility that generates electricity. There are many different types of power plants, including coal-fired, natural gas-fired, hydroelectric, and nuclear power plants. The electricity generated at these plants is sent out through transmission lines and delivered to homes and businesses through the National Grid.
A transmission line is a type of electrical cable that is used to transmit high-voltage electricity over long distances. Transmission lines are usually made of metal and are supported by towers or poles, and they play a crucial role in delivering electricity to homes and businesses all across the country.
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