Calculating %Z from %IZ

[RazmikH]

I recently ordered a few 208V to 208V isolation transformers. I asked the manufacturer for the impedance data. I was given %IZ, %IX, and X/R. When I calculate the %Z, the results are larger than expected. I may be doing something wrong. Can anyone tell me how to calculate the %Z from the provided data? These are 15kVA to 150kVA transformers.

 

[waross]

Use the nameplate data to calculate the impedance and reactance in ohms instead of PU.
Then use the X/R ratio and Pythagoras' theorem.

Bill
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"Why not the best?"
Jimmy Carter