Thanks! I looked at the IEC technical report. What do they mean by "rated short circuit voltage"? Is this the given fault current for the voltage shown in the table expressed in a % value? The use of voltage is throwing me off in this case.
I did find this word doc which actually lists recommended % impedance for the IEC and IEEE:
By chance, does anyone know how these numbers are derived? Are they just arbitrary based on industry preference or is there a solid engineering reason behind these recommendations?
In this application BIL is in the 450 to 550 range.
My mistake. The actual BIL for "common" transformers is either 450 or 550 out in the system for various reasons, but the new units will be 550 BIL.
I am debating between 10 and 12% Z (base self cool rating). I did check and the X/R in newer units is significantly lower on resistance. My reason for nit picking these value is because parallel use transformers is expected to go up and I would like to have all units be the same Z.
In terms of fault current, anything I should look out for other then the obvious 3x increase assuming infinite source?
