Correct Answer - Option 2 : reduce eddy current losses
- When an alternating magnetic field is applied to a magnetic material, an emf is induced in the material itself according to Faraday’s law of Electromagnetic induction.
- Since the magnetic material is a conducting material, these EMF’s circulates current within the body of the material. These circulating currents are called Eddy currents. They are produced when the conductor experiences a changing magnetic field.
- The process of lamination involves dividing the core into thin layers held together by insulating materials.
- Due to lamination effective cross-section area of each layer reduces and hence the effective resistance increases.
- As effective resistance increases, the eddy current losses will get decrease.
Eddy current loss in the transformer is given by:
Pe = Ke Bm2. t2. f2. V Watts
K - coefficient of eddy current. Its value depends upon the nature of magnetic material
Bm - Maximum value of flux density in Wb/m2
t - Thickness of lamination in meters
f - Frequency of reversal of the magnetic field in Hz
V - Volume of magnetic material in m3
From the above formula, we conclude that the Eddy current loss is proportional to the square of the frequency.
Since the Eddy current loss is proportional to the square of the thickness of the lamination.
∴ The eddy current loss in a transformer can be reduced by decreasing the thickness of the laminations.