Calculate the transformer parameters

[fred2028]

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?

 

[rock.freak667]

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.