The Maximum current in a transformer

AI Thread Summary
The discussion focuses on deriving the maximum current in a transformer, specifically the equation Imax = (N2/N1)^2 * (Emax/R). Participants emphasize the importance of understanding how voltage and current ratios transform through the transformer, using the relationships I2/I1 = N1/N2 and V1/V2. They suggest manipulating these equations to relate secondary resistance to primary load impedance. A key point raised is the conservation of energy in the transformer, indicating that the product of voltage and current remains constant between primary and secondary sides. Understanding these principles is essential for solving transformer-related problems effectively.
claybrow
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I have attached the problem. This is a practice exam and the answer Imax = (N2/N1)^2 * (Emax/R) but I have no idea why. I have been trying to manipulate the transformer equation I2/I1 = N1/N2 = V1/V2 but to no avail. Thanks
 

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claybrow said:
I have attached the problem. This is a practice exam and the answer Imax = (N2/N1)^2 * (Emax/R) but I have no idea why. I have been trying to manipulate the transformer equation I2/I1 = N1/N2 = V1/V2 but to no avail. Thanks

Welcome to the PF.

To derive the equation to transform the load impedance from the secondary to the primary, start with the two equations for how voltage and current are transformed going through the transformer:

I2 = ?? * I1

V2 = ?? * V1

And then take whatever ratios you need to in order to see how the secondary resistance transforms to the primary side (that it, what load resistance the primary voltage drive source sees, based on the turns ratio)...
 
Just to add to what Berkeman has said, use the clue that there is no energy lost in the transformer. What does that tell you about the product EI in the primary and secondary?
 

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