The Transformer

(Primary has NP turns) (Secondary has NS turns)

•The source side is called Primary•The load side is called Secondary

1. When current in the primary coil changes being alternating in nature, a changing magnetic field is produced2. This changing magnetic field gets associated with the secondary through the soft iron core3. Hence magnetic flux linked with the secondary coil changes.4. Which induces e.m.f. in the secondary.

Principle of operation of Transformer

Ideal Transformer

1.The resistance of the coils are zero.

2.The relative permeability of the core in infinite.

3.Zero core or iron loss.

4.Zero leakage flux

Unsolved Example

N1:N2 = 1:2

i) Find I1, I2 in the above ideal transformer. ii) What is the reflected (referred) load impedance on the primary sideiii) If the resistance is replaced by (a) 100 mH inductor (b) 10F capacitance; what will be the reflected load impedance on the primary side?