Ferranti Packard Transformers Winding Resistance

In our system we have Ferranti-packard transformers with LTC type 25 RT 32. These are the 1983/84 vintage, primary 138KV delta and secondary 13.8KV Y-G.

most of the transformers has a high winding resistance difference comparing among different phases, up to 25% difference, comparing to the IEEE guideline 5%.

Is any one out there has readings for this similar transformers?

We are measuring the sister units for comparisons, but the WR reading of each transformer is quite different to compare. One may have high WR on X1-Xo in all tap positions, the other one may have high WR X2-Xo and only in odd tap positions, the other one in even positions, etc.

Thank you,