TX X% HOW HIGH???

[pavement]

Im currently running some simulations for fault levels within a system, and using marine transformers that have X% of 16.1 and 12(1.4 and 3MVA respectively).Obviously the route of higher transformer impedences has to be explored to bring fault levels down.However as my practical experience is limited, I was wondering practically how high can the X% go in feasible terms, so i can stay in ballpark territiory.

Many Thanks

 

[busbar]

Preferred percent impedance volts in ANSI C12.57.10 are more in the range of 5.5-8% for sizes cited; somewhat dependent on winding voltages. Although higher-impedance transformers will have reduced secondary short-circuit currents, consider tradeoffs in terms of increased load losses and “looser” voltage regulation.