When I read the lecture notes about the ideal transformer, I have some problems about the proof of current relationship i1/i2=N2/N1=1/a.The proof is shown below.(adsbygoogle = window.adsbygoogle || []).push({});

Current Relationships of ideal transformer:

To get the current relationships use ampere's law

mmf= ∫H•ds= N1i1+N2i2’

H x length = N1i1+N2i2’

(B x length)/μ = N1i1+N2i2’

Assuming uniform flux density in the core

(φ x length)/( μ x area) = N1i1+N2i2’

If μ is infinite then 0 = N1i1+N2i2’ Hence i1/i2’= -N2/N1 or i1/i2=N2/N1=1/a

Questions:

1.when μ becomes infinity , is B still directly proportional to H here (is B=μH still worked )?

2.If μ becomes infinity then by B=μH as H has some values ,B becomes infinitely large?? μ=∞ ; B=μH=∞? But B will go saturated in reality...It contradicts that B=μH.

If B≠μH then mmf =Hl≠ φ x (l/μS) where l/μS is the reluctance .

Is the reluctance l/μS not suitable for the saturation region of B-H curve?

3. I have read the book Power System Analysis by William D. Stevenson (P.45),the author said that B is not infinitely large,therefore integral value of must equal to zero.I don't understand his explanation.Can anyone explain in details to me? Thanks.

Another question: in reality,there is flux leakage around the core ,how can we use the ampere 's circuital law to calculate them?The leakage flux have many path...

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# Ideal Transformer current relationship and problems of B-H relationship

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