national grid

• national grid is giant system of cables and transformers that carries electricity around the country
• national grid uses high pd which means less current is needed and less energy is lost from heated wire
• powerstations generate 25000 volts
• step up transormers increase the pd from 25000 to 400000
• resistance heats up transmission cables so it gives off thermal energy to the surrounding air
• step down decrease pd so homes, schools and factories can have safe amount of energy
• step down reduce pd from 400,000 to 230 volts for schools and homes
• step down decrease pd to 33,000 or 100,000 volts for factories