I am not an engineer or electrician.

Here's how I think the math works, and I will explain each step:

600 volts RMS  < ----This is ACROSS the phases, not phase to neutral

347 volts RMS <--- Phase to neutral

400 amps is 3-phase < ---- This is the most important part.  You have 3 phase power but are running 1 phase units.

Using https://canadatransformers.com/transformer-phase/ to calculate KW/KVA using all 3 phases:

600v x 400 amps = 415.69 KVA

(600 x 400 x 1.732)

Calculate using a single phase:

347v x 400 amps = 138.8 KVA

Yup checks out, it's 1/3 of the 3 phase.  So we have a total system KVA of 415.69.  To translate to KW we need to multiply by the power factor:

415.69 KVA x 0.99 = 411.5 KW

So we have a total system KW available of 411.5, multiply by 0.8 (80%) to get available power:

411.5 * 0.8 = 329.23 KW available

Divide by 1.475 KW:

329.23 / 1.475 = 223 units

That's a lot!

Where are you located?  I'm in Winnipeg.  What is the size of the transformer in kva?

Edit: I did not include transformer losses since we need to knock down that 600v further.