Correct Answer - Option 2 : reduce eddy current losses
Concept:
- 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
Where;
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.
Application:
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.
