Transformer Calculations

The primary voltage is 480, secondary is 120. kVA = 15 and Impedance is 4.4%. Sorry forgot to include that.

Regards.

As per IEEE standards and Table No-1.2, X/R ratio=0.867 when %Z=2.7789

In this case, %Z=4.4,

so X/R= 0.867*4.4/2.7789= 1.373

Ask Manufacturer-

only he can supply this (else test at your place)

The other option is refer the IEEE std 242 which will give the recommended value of it for different ratings (same as ANSI C57)

And last, most approximate is a thumbrule about 4.9