Unusual transformer

[greg crosby]

I have to supply 480v for a 5hp. 25FLA pump. I have a 120/208 4 wire Y service. I have a 30kva transformer. What should the primary and secondary be protected at? Please show calculations. Thank you. First time for a backward set up. No choice

 

[Rick Christopherson]

????
HP = 480 x 25 FLA x 0.8 x 0.85 / 746 = 11hp @ 1-p or 18 hp @ 3-p

5 hp with 25 FLA equates to a 240 volt, single phase motor. Something is not right with your numbers.