- A transformer is used to raise and lower AC voltages
- As a result, it raises and lowers current, but not power (unless inefficient)
- It is simply two coils wrapped around a common soft iron core
- It has a primary source, connected to the power source, and a secondary source which is connected to the load.
Only AC power can be used in a transformer.
This is because it changes direction of EMF, hence, a change in flux occurs.
This change in flux induces a magnetic field, which induces an EMF in the secondary coil
If DC power was used, there would not be any change in flux, hence no EMF produced.
- Varying flux in a transformer produces eddy currents
- They reduce the efficiency of the transformers
- To prevent them, laminations are used
Poutput = P input assuming 100% efficiency
Inefficiencies only affect current
Voltage is unaffected ( in this course)
- Electricity is produced by large AC generators
- Two main concerns: minimising power loss, whilst supplying sufficient power
P loss = ΔV I
Where ΔV = voltage drop of the cables during transmission, I = transmission current
P = I2 R
To reduce P loss, reduce I and R
- That is, increase total EMF
- This reduces transmission current, reducing power loss
- OR reduce R by using more conductive material, large diameter cables, shorter cables