ECN Forum Forums General Topics of the Trade General Discussion Area Sizing a Transformer

Here you go:
Amps = 1000 × kVA / (√3 × volts)

Amps = 1000 × 150KVA / (1.73 × 208V)
The 208Y/120V output of a 150kVA transformer is 416.7 Amps.

Keep in mind that this is does not take into account any reduction due to harmonics generated by the solid state switching power supplies in the computer equipment.