The national grid Flashcards
what are the different parts of the national grid?
-power station
-step up transformer
-pylons and cables
-step down transformer
-consumer
describe a power station
it has a high current and a low voltage
what does a step up transformer do?
increases potential difference
describe pylons and cables
it has a low current and a high voltage
what does a step down transformer do?
it decreases potential difference
describe the consumer
it has a high current and a low voltage
what is the role of a generator?
generates electricity that is then transported around the country
what is the role of pylon?
support the electric cables
what is the role of cables?
transports electricity around the country
what is the role of a transformer?
increase and decrease voltage at particular stages
The current inside the cables is kept low and the voltage kept high. The opposite is true at the power station in your home, why is this?
-a step up transformer will increase the potential difference to the electrons in order to flow
-as potential difference increases the current decreases
-the flowing electrons are now less but each one carries more energy
-less electrons flowing around means there are less collisions with the fixed ion inside the cable
-fewer collisions means less KE transferred to the fixed ions and eventually turned into heat
-less heat energy escaping means less wasted energy transferred to the surroundings
what are the advantages of overhead cables?
-air acts as electrical insulator
-less expensive to install and maintain
-quick to repair
what are the disadvantages of overhead cables?
-spoils view
-danger to low flying aircraft
-affected by severe weather
what are the advantages of underground cables?
-cannot be seen
-no hazard to aircraft
-unlikely to be damaged by weather
-reduced shock hazard
what are the disadvantages of underground cables?
-repairs take longer and are more expensive
-expensive to install
-need layers of electrical insulation
what are the different parts of a coal power station?
-coal arrives by train or truck
-furnace
-boiler
-cooling tower
-turbine
- generator
-transformer changes the voltage
what happens in the furnace?
coal is burnt
what energy transfer happens in the furnace?
chemical energy is converted in the coal to thermal energy
what happens in the boiler?
water is heated and turned into steam
what energy transfer happens in the boiler?
thermal energy is converted to kinetic energy of the moving steam
what happens in the turbine?
steam hits the blades of the turbine and it turns it around
what energy transfer happens in the turbine?
kinetic energy of the moving steam is converted to kinetic energy of the turbine
what happens in the generator?
a coil is turned inside a magnetic field and an electric current is produced
what energy transfer happens in the generator?
kinetic energy of the moving coil is converted to electrical energy in wires
