P5 - mains electricity Flashcards
What are the 3 parts of a power station and their functions
Furnace - fossil fuels burned to heat water
Turbines - steam turns turbine
Generator - turbine turning produces electricity
What voltage are the 6 parts of the national grid
Power station - 25000V
Step up transformer - 25000V to 400000V
National grid network - 400000V
Step down transformer - 400000V to 330000V
Local transformer - 330000V to 250V
Home - 250V
What do the different parts of the national grid do
Step up transformer raises voltage and reduces current to reduce resistance and therefore reduce heat loss
National grid network transfers electricity across the country - power lines
Step down transformer lowers voltage from grid
Local transformer substation lowers the voltage again for use in homes
What is the difference between AC and DC
Direct current is where the current flows in one direction
Alternating current is where the current alternates both directions
What are the max, min, and average voltages of AC
Maximum: 325V
Minimum: -325V
Average: +- 230V
What frequency is mains electricity
50HZ
Word equation for power in terms of voltage and current
Power = current x voltage
Symbol equation for power in terms of voltage and current
P = IV
What do fuses do
They have a thin wire that melts if the voltage gets too high once it exceeds the fuses rating, they prevent fires not electrocution
What colour and voltage is the live wire
Brown, 230V, goes into device
What colour and voltage is the neutral wire
Blue, 0V, completes the circuit
What colour and voltage is the earth wire
Green and yellow stripes, 0V, goes into ground
What are plug pins made of and why
Brass because it is a good conductor and not malleable
What does the cable grip do
Stops you pulling the cable out
Why do you need the earth wire
In case the live wire touches the neutral wire
