The 1.732, which is sqrt(3), merely takes you from knowing I and E for a single phase and figuring out the total for all three phases (assuming a balanced load).http://www.elec-toolbox.com/Formulas/Useful/formulas.htm
E x I x 1.732
Since you have kva, just multiply by 1.732 I guess. Wait for confirmation from someone smarter than I.
by Aaron Carman
by Duane Benson
by Aaron Carman