the national grid

• what is the national grid

  - the network of high voltage power lines between major power stations

  
  

  - it distributes electricity from power stations to comsumers
• transformer


  used to change potential difference on the national grid
• step-up transformer


  - used just after the power station

  - increases voltage

  - decreases current
• step-down transformer


  - used just before houses

  - decreases voltage

  - increases current
• why is the voltage reduced before it reaches houses

  makes sure its safe to use - the voltage during transmission would be dangerous to use in houses
• why is the potential difference increased before being transmitted

  - reduces energy lost due to heat

  - by using a lower current

  - improves efficiency of the NG
• power formula


  power = PD x current
• power units


  watts (W)