The limits depend on the type of soil, water conditions, and the size of the vibrator(roller or otherwise). For expample if you are using a small walk behind roller compacting a damp sand (i.e. near optimum) then you may be able to compact up to 12 inches, although 6 to 9 inches is more likely. In the same conditions, a plate compactor might get 6 inches with 4 to 8 passes.
If you could be more specific, we might be able to help you better. But in general terms, vibratory compaction equipment will penetrate less than 1 foot unless very large equipement is used in which case 2 to 3 feet might be possible.