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They step down the voltage from the main power generating stations at different intervals so that for a domestic power service it is delivered at 240V.
Additional answer
When you pass electricity through wires you warm the wires up. This heat is a total loss of energy. So you want to keep the loss to a minimum. The heating effect of electricity is increased with an increase in amperage (the current). The amount of power that goes through the wires is a function of the voltage x amps. So to transmit a certain amount of power with the minimum heat loss you keep the current down which mean pushing the voltage up. This is why the transmission wires near the generating station carry very high volatges. But these voltages are unsafe for use in domestic circuits so they have to be reduced by a series of Transformers from the high voltages in the main lines to lower voltages at substations to even lower voltages in the home.
For more information see the answers to the Related questions shown below.
What else can I help you with?
How many electric transmission transformers are there in the US transmission grid?
500
How many pylons are there in the national grid?
In the National Grid there are 876 thousand pylons.
What is a system that links electricity produced in power stations to deliver it to where it is needed?
Power Systems or Transmission & Distribution
How energy losses are minimised when electricity is distributed through the national grid?
Explain how energy losses can be minimised when converting it into forms for use by consumers: Transformers help. Step-up Transformers convert a low voltage and a high current. The low current loses less energy over long distances. A step-down Transformer does the opposite and can likely be found somewhere down the street from you (in America they are the large green boxes that you are told never to touch). Electricity is supplied to consumers through the National Grid at a very high voltage to reduce energy losses during transmission. Transformers are used to increase or decrease the voltage of the supply. Electricity is charged in units. One unit is equivalent to one kilowatt of electricity used for one hour. Power stations are built in order to generate electricity. There are four main stages: *the fuel is burned to boil water to make steam. *the steam makes a turbine spin. *the spinning turbine turns a generator which produces electricity. *the electricity goes to the transformers to produce the correct voltage. The energy needed to boil the water comes from fossil fuels or nuclear fuels. Renewable energy resources such as wind and wave power may drive the generators directly. The National Grid: Electricity is transferred from power stations to consumers through the wires and cables of the National Grid. When a current flows through a wire some energy is lost as heat. The higher the current, the more heat is lost. To reduce these loses, the National Grid transmits electricity at a low current. This needs a high voltage. Power stations produce electricity at 25,000V. Electricity is sent through the National Grid cables at 400,000V, 275,000V and 132,000V. Step-up transformers are used at power stations to produce the very high voltages needed to transmit electicity through the National Grid power lines. These high voltages are too dangerous to use in the home, so step-down transformers are used locally to reduce the voltage to safe levels. The voltage of household electricity is about 230V. energy transferred (kWh) = power (kW) x time (h)
Single phase consumer distribution systems are supplied from what?
The national electrical grid.
Why does the national grid use AC current?
transformers
How is electricity transported and distributed?
The electricity is transported and distributed by the use of the national grid and the step down and the step up transformers.
How do transfromers reduce energy lose through the national grid?
Transformers reduce energy loss through the national grid by stepping up the voltage for long-distance transmission, which reduces the current flowing through the lines and consequently reduces energy lost as heat due to resistance in the wires. By stepping down the voltage back to usable levels for end-users, transformers deliver electricity more efficiently across the grid.
Why step up transformers used in the national grid?
Electrical generators work at about 11,000 volts which is not enough to transmit power over long distances over about 5 miles. Therefore step-up Transformers are used to connect them to the local grid on 132 kV or the supergrid on 275 or 400 kV (in the UK)
When was At the National Grid created?
At the National Grid was created in 2005.
What is the job of a dynamo in the national grid?
The national grid is a means of distributing electricity, there is no need for a dynamo (which produces electricity) in the national grid. However, dynamos (generators) are needed in the power stations.
How is electric supply related to the National Grid?
Electric supply is related to the National Grid in that the National Grid is composed of many supply lines that direct electricity to the National Grid, and this in turn powers the country.
How many electric transmission transformers are there in the US transmission grid?
500
How many pylons are there in the national grid?
In the National Grid there are 876 thousand pylons.
What is National Grid plc's population?
The population of National Grid plc is 2,012.
When was National Grid plc created?
National Grid plc was created in 1990.
How does national grid make electricity?
The North American national grid does not make the electricity. The grid is a distribution system that transports power throughout the system to homes that are connected to it. The power for the grid is produced elsewhere at generating stations that feed into the grid.
