Convert transformer resistance data from Watts to Ohm
I looked at some transformer test results for a 60 MVA 132/33kV transformer, and found this in the test results:



This seems to suggest that the resistance, in percent on transformer MVA base (60 MVA), is simply Load Loss [W] ÷ Transformer MVA Base [MVA]. In this case, that's 381,000 W ÷ 60,000,000 MVA = 0.635%. Enter this for 'I/O Code 2'.

Similarly, the percent impedance on system MVA base (typically 100 MVA) would just be 381,000W ÷ 100 MVA = 0.381%. Enter this for 'I/O Code 1'.