2.3
2.3 answers 24 November 2010 10:12 • 2.3 describe the uses of insulation, double insulation, earthing, fuses and circuit breakers in a range of domestic appliances Insulation
· Usually plastic Double Insulation
· Wire to appliance is insulated
· Appliance casing is insulated
· Examples = computer monitor, plastic kettle, etc Fuses
· http://www.youtube.com/watch?v=mk0p_zTaFzY
· Made of a thin piece of wire
· When current is too high the wire gets hot and melts
· The fuse "blows"
· UK plugs are fused Earthing
[cid:image001.png@01CCB407.E526FC90] Electric toaster - circuit working normally Live Neutral Earth
[cid:image002.png@01CCB407.E526FC90] Live Neutral Earth
[cid:image003.png@01CCB407.E526FC90] Live Neutral Earth
· A large current flows through the metal casing and down the Earth wire
· This melts/"blows" the fuse which breaks the circuit
· This prevents electrical fire Circuit Breakers
· http://www.youtube.com/watch?v=mKJ5eTJBDyA
· RCD = Residual Current Device
· An RCD can break the circuit much faster than a fuse
· Prevents electric shock 2.3 Build a plug animation 25 November 2011 15:50
> 2.3 Plenary - harder questions 25 November 2011 15:51 PFY p.276, Q.8 a to d only
[cid:image004.jpg@01CCB407.E526FC90]
· Usually plastic Double Insulation
· Wire to appliance is insulated
· Appliance casing is insulated
· Examples = computer monitor, plastic kettle, etc Fuses
· http://www.youtube.com/watch?v=mk0p_zTaFzY
· Made of a thin piece of wire
· When current is too high the wire gets hot and melts
· The fuse "blows"
· UK plugs are fused Earthing
[cid:image001.png@01CCB407.E526FC90] Electric toaster - circuit working normally Live Neutral Earth
[cid:image002.png@01CCB407.E526FC90] Live Neutral Earth
[cid:image003.png@01CCB407.E526FC90] Live Neutral Earth
· A large current flows through the metal casing and down the Earth wire
· This melts/"blows" the fuse which breaks the circuit
· This prevents electrical fire Circuit Breakers
· http://www.youtube.com/watch?v=mKJ5eTJBDyA
· RCD = Residual Current Device
· An RCD can break the circuit much faster than a fuse
· Prevents electric shock 2.3 Build a plug animation 25 November 2011 15:50
> 2.3 Plenary - harder questions 25 November 2011 15:51 PFY p.276, Q.8 a to d only
[cid:image004.jpg@01CCB407.E526FC90]

