The Maximum current in a transformer

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SUMMARY

The maximum current in a transformer can be calculated using the formula Imax = (N2/N1)^2 * (Emax/R), where N1 and N2 are the number of turns in the primary and secondary coils, Emax is the maximum voltage, and R is the load resistance. The transformation of current and voltage in a transformer is governed by the equations I2/I1 = N1/N2 and V1/V2 = N1/N2. Understanding these relationships is crucial for manipulating transformer equations effectively, especially when considering the conservation of energy principle, which states that the product of voltage and current remains constant across the transformer.

PREREQUISITES
  • Transformer equations: I2/I1 = N1/N2 and V1/V2 = N1/N2
  • Understanding of turns ratio in transformers
  • Basic electrical principles, including Ohm's Law
  • Knowledge of load resistance and its impact on transformer performance
NEXT STEPS
  • Study the derivation of transformer equations in detail
  • Learn about energy conservation in electrical circuits
  • Explore the impact of load resistance on transformer efficiency
  • Investigate practical applications of transformers in electrical engineering
USEFUL FOR

Electrical engineering students, educators, and professionals involved in power systems or anyone seeking to deepen their understanding of transformer operation and calculations.

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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