Why are transformers used in the National Grid?

The National Grid is how electricity is distributed from suppliers to consumers (commercial or private household). Power stations produce power in the region of Mega Watts (the order of millions of watts) and we want as much of this power to be transferred efficiently (without losses) to be used by consumers. There are two equations which are important to consider:

  1. Power loss in a line = current^2 x resistance of the wire (written as P = I^2 x R)

  2. Power = current x voltage (written as P = I x V)

Looking at equation 1) we see that in order to minimise power losses in the line we need to have as small a current as possible (the resistance of the wires is constant). Equation 2) tells us that for a constant power, in order to have low current we must increase the voltage.

Step-up and Step-down transformers are used to increase and decrease voltage respectively. Once electricity is generated from the power station (~20,000V) it is 'stepped-up' to between 132,000V and 420,000V and distributed via cables to consumers. Mains electrics (what we use in our homes) runs at 230V, so a step down tranformer is needed to reduce the voltage to this safe level.

Answered by Mike R. Physics tutor

14136 Views

See similar Physics GCSE tutors

Related Physics GCSE answers

All answers ▸

How to i calculate total resistance in a circuit?


How do you improve measurements and reduce error in a physics lab experiment?


A coil is connected to a voltmeter. A bar magnet, initially held above the coil, is left to fall into the coil. Explain why the voltmeter shows a reading. How will the reading of the voltmeter be affected if the magnet is dropped from a greater height?


Calculate the acceleration of particle thats velocity changes from 20ms^-1 to 40ms^-1 in 5 seconds, assuming its constant.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2024

Terms & Conditions|Privacy Policy
Cookie Preferences