I have a 800 amp 120/208 3P stand up section that feeds a step up 90kva transformer and the loads are nearly equal? I thought that after the transformer the load of 277/480 would be drawing less. We have about 500 amps per phase being drawn in front of the transformer and the load at the sub panel it feeds is about 480 amps. Is this normal?

Need to know if the 800 A switchboard is only feeding the 480 volt transformer. I suspect not, that there are other loads in addition to the transformer.

Are you sure the 120/208 section is feeding the transformer, and not the other way around? While it is possible to be using the transformner to step up the voltage, and it not that rare, it is not that common.