Calculate the transformer parameters

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SUMMARY

This discussion focuses on calculating transformer parameters through open circuit tests (OCT) and short circuit tests (SCT). The equations presented include V = (I * cos(theta)) * R and V = (I * sin(theta)) * X for OCT, emphasizing the use of real and imaginary components of current. For SCT, the formula P = I^2 R is questioned, with a suggestion to use P = (I * cos(theta))^2 * R instead, highlighting the importance of using the real component of current for accurate power calculations. The relationship between resistance (R) and reactance (X) in series during SCT is also clarified.

PREREQUISITES
  • Understanding of transformer operation and testing methods
  • Familiarity with electrical engineering concepts such as impedance and phase angle
  • Knowledge of power calculations in AC circuits
  • Proficiency in using trigonometric functions in electrical formulas
NEXT STEPS
  • Study the principles of open circuit and short circuit tests for transformers
  • Learn about the significance of real and reactive power in AC circuits
  • Explore advanced transformer modeling techniques using simulation software
  • Investigate the impact of core losses on transformer efficiency
USEFUL FOR

Electrical engineers, students in power systems, and professionals involved in transformer design and testing will benefit from this discussion.

fred2028
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Question basically asks to find the parameters of a transformer via an open circuit and closed circuit test. We were taught that for OCT,

V = (I * cos(theta)) * R
V = (I * sin(theta)) * X

To find the core losses. This makes sense, since we are only using the component of the current that is parallel to the real and imaginary impedances. However, for the SCT, we were taught

P = I^2 R

Wouldn't it be more logical to use

P = (I * cos(theta))^2 * R

since P is the real component of S, and therefore we should use only the real component of current I?
 
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In the SCT the R and X would be in series so the same current at the phase angle of zero would be passing through both R and X.
 

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