@Voltcat: Clearly you have no idea what you are doing, much less what you are asking. I suggest you consult with someone who does this sort of thing and is licensed and insured before you either electrocute yourself or cause an electrical fire you won't have any idea how to extinguish.
Three-phase power delivered at the levels you are considering is NOT a job for amateurs. And it will take more than just one rectifier, probably more like six rectifiers plus a three-phase step-down transformer to get the voltage down to 120 V DC from three-phase 480 VAC. Dry transformers rated for the power levels you seek are about two feet wide by two feet deep by two feet high and weigh several hundred pounds. Not something the typical amateur or hobbyist, which is who this site is aimed at, is used to messing with.
It should be possible design and build a three-phase switch-mode power supply that would provide the performance you seek in the volume (size) you suggested, but again, that is no job for an amateur or the typical hobbyist. And these DC power supplies probably already exist on the open market. Make Google your best friend and go find one.
I suggest that a moderator close this thread.
