Question

On which of the following do the eddy current losses depend ?

I. Nature of the material

ll. Maximum flux density

Ill. Frequency

Choose the correct answer from the options given below.

1. I, II and III
2. II and III
3. I and II
4. I and III

Answer 1

Correct Answer - Option 1 : I, II and III

Concept:

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 ∝ f2

Hysteresis losses: These are due to the reversal of magnetization in the transformer core whenever it is subjected to the alternating nature of magnetizing force.

\({W_h} = \eta B_m^{1.6}fv\)

Where, η = Steinmetz constant

Bm = maximum flux density

f = frequency of magnetization or supply frequency

v = volume of the core