Wow I feel a bit light-headed reading your post!
Let's clarify some things: Where did you read the 7.5KVA rating?
If it's on a single line diagram it could be the load on the panel. If it's fed from a 7.5KVA transformer, then the panel can only supply 7.5KVA (perhaps xfmr can be overloaded further but that's another question). Neither scenario will tell you what the ampere rating of the panel is. You could load a 400A panel to 7.5KVA or feed it from a 7.5KVA transformer as long as OCPD and conductors are sized properly.
They list the panel as such likely because it's being fed from an isolation transformer, hence my guess at the 2nd scenario above.
You're either on site or looking at drawings, either way can't you find out if it's a hospital?