Distribution and safety of electricity Flashcards
What is AC: Alternating Current?
Current that flows backwards and forwards
What is DC: Direct Current?
Current that flows in the same direction all the time
Tell me the whole National Grid set up
About 5 things it goes through i guess?
- Power station
- Step-up transformer
- National Grid System
- Step-down transformers
- 240v to your home or something
volts in ur home like electricity OR SOMETHING
What do network of pylons do?
Supports electrical cables needed to carry electricity around
What are large transformers used for?
- Step-up/down voltages
* Used in the National Grid
3 advantages and disadvantages of overhead wires :v
Advantages:
· Easy to be fixed
· Cheap
· Easy to see
Disadvantages:
· Can be hit by flying vehicles
· Dangerous
· Ruined scenery
3 advantages and 2 (¬.¬) disadvantages of underground wires >:(
Advantages:
· Safer
· More space on surface
· Keep natural beauty
Disadvantages:
· Hard to repair and build
· Expensive
Why is it important that the National Grid is able to respond quickly to changes in electricity demand?
A blackout may occur or powercut
2 situations the National Grid power company would need to alter the amount of power available to the Grid?
· Winter time
· East Enders????
Whats the base load in a graph meant to show?
The amount of power power stations need
How does the national grid meet the rise in demand?
right before transformer page
Hydroelectric dams are opened
What does a step-up transformer do?
Increase the voltage but decrease the current
What does a step-down transformer do?
Decrease the voltage but increase the current
Why is it important that the national grid must have transformers?
Increased current distributes extreme heat on the wires therefore voltage increases. Additionally, voltage is stepped down so it’s safer for use when it arrives to homes
The page u are left seen on the book, is literally about calculations And I mean: · Electrical energy and power · Units of electricity · Cost of electricity · Payback time
Just look over them on the book
Yes, Thanks :)
If current flows in only one direction it’s called..?
Direct current
If current constantly changes direction is is called…?
Alternating current
Make sure u look at that DC and AC current page
I suppose, but I mean I might forget
What are the 3 main wires that run through your house as part of the ring main circuit?
· Live wire (brown)
· Neutral wire (blue)
· Earth wire (green and yellow)
Definitions are going to be separated
What does the live wire (brown) do?
· Brings in the alternating current/voltage
· Always connected to fuse or mcb (switch that turns off everything in the house sometimes)
What does the neutral wire (blue) do?
· Takes the current out of your home
What does the earth wire (green and yellow) do?
· Used for safety
· Stops you from getting electrocuted
· Takes electricity into the ground
What does a fuse do?
· A fault in an appliance can cause the current to be too great leading wire to overheat and possibly cause fire
· Fuse designed to melt if current through circuit is too high, thereby breaking the circuit
· Fuse should be higher than normal working current
What current does wire melt?
1.56
Idk it’s in booklet
Read earth wire page
FF FFFFFFine
What do miniature circuit breakers (mcb’s) do?
· Protect the device from high currents
· Use an electromagnet, activates if too high a current flows
· Magnet attracts a switch, breaking the electrical circuit
· Faster than fuses cuz they can be reset
· Acts faster than fuses cuz more sensitive
What doe residual current circuit breakers (rccd’s) do?
· Protect the user from electrocution
· Use an electromagnet to detect difference between live and neutral wires’ current (I assume)
· If there’s a difference in current between live and neutral wires, electromagnet activates breaking the circuit
