The national grid

• • the national grid is a giant system Of cables and transformers that covers the UK and connects power stations to consumers
• • throughout the day electricity usage (the demand) changes. Power stations have to produce enough electricity for everyone to use it at the same time
• The national grid uses a high pd   and a low current, as it is cheaper because thermal energy is lost When using Current
• To get the pd to 400000 v, we use transformers
• Transformers:

  • All have two coiIs, a primary one and a secondary one Joined with an iron core
  • they have more turns on the secondary coil than the primary one and as the pd is increased by the trans former, the current is increased
  • the pd is then reduced again by a step-down transformer, which increases the current as it has more turns on its primary coil