Correct Answer - Option 3 : 0.5 mm
Eddy current loss:
- Eddy current loss is basically I2 R loss present in the core due to the production of eddy currents in the core, because of its conductivity.
- Eddy current losses are directly proportional to the conductivity of the core.
- Eddy current losses can be reduced by either by adding silica content (4% - 5 %) to steel or by using a laminated core instead of a solid core.
Eddy current loss is given by We = KB2m f2t2
Where,
K = π2/ 6ρ,
Bm = maximum flux density,
f = supply frequency,
t = thickness of the laminations
If maximum flux density is constant, and thickness also constant,
In that case, eddy current losses are directly proportional to the square of the frequency.
We ∝ t2
- In order to reduce the eddy current losses, we use laminations
- In a DC machine, laminations are used to reduce eddy current losses and for insulation purposes. The approximate thickness of laminations is 0.5 mm.
- The stator frame consists of laminations of silicon steel, usually with a thickness of about 0.5 millimetre.
