4.5 The National Grid Flashcards
Name the 2 components that make up the national grid
- pylons
* cables
Name 3 examples of where the national grid distributes electricity to
- homes
- schools
- factories
Why can power stations around Britain be switched on and off depending on demand?
The whole country is connected to the national grid
What does the fact that the whole country is connected to the national grid mean?
That power stations all over the country can be switched on and off according to demand
Where are the cables carried in the countryside?
By overhead pylons
Where are the cables carried in towns close to homes?
Under the ground
Give two advantages of overhead cables to underground cables
- easier to repair
* cheaper
What is the minimum voltage of the national grid?
132kV
What is the average voltage of power stations?
25kV
When electricity is moving from the power station to the houses, where does the voltage increase?
Step up transformer
When electricity is moving from the power station to the houses, where does the voltage decrease?
Step down transformer
Why is the voltage increased at step up transformers?
Higher voltage means lower current. Lower current means less resistance. Less resistance means less energy wasted as heat which makes the system more efficient
Why do we use step down transformers?
To reduce the voltage to a suitable voltage to go into the homes
What is the voltage that goes into homes?
230V
What sort of transformers are used at local substations?
Step down transformers
