National Grid Flashcards
How is electricity distributed?
Electricity is distributed via the national grid.
What is the national grid made up of?
It is a system of transformers and cables.
What does the national grid connect?
It connects power stations and consumers.
The national grid transfers power from power stations (the supply) to anyone on the national grid who needs it (the demand).
How does electricity production meet the demand?
They do this by predicting times when the power usage is higher.
What times is the power consumption higher than usual?
When people wake up
When people come home from school or work
When it is cold or dark outside
When there is an important event on TV
Why do power stations run below their maximum power output?
They do this to conserve energy and also so that they have enough capacity to cope with a high demand.
What is also kept on stand by?
Smaller power stations are kept on stand by as they can start up quickly if needed.
Describe the PD and current of the national grid?
They have a high PD and a low current.
A high current will cause cables to heat up and loose a lot of energy. So a high PD is used.
A high voltage of 400000V is used so that the power can be high.
For a given power, increasing the PD will decrease the current so there is less energy being lost as heat. This means that the national grid is efficient.
What changes the PD?
The PD is changed by transformers, pylons and insulators.
What is used to step up and step down the PD?
A step up transformer is used to step-up the PD
A step down transformer is used to step-down the PD
