The use of  "Bergen Raises" is based on the Law of Total Tricks.  It applies when your partner opens 1 of a Major.  Using Bergen Raises an immediate jump to the 3 Level carries a different meaning then in standard bidding.  It is typically presented as follows: 

         Assume that there is no interference:
            1H:2H would show 6-9 points with 3 Hearts
            1H:3C would show 6-9 points with 4 Hearts
            1H:3D would show 4 Hearts and 10-12 Points.
            1H:3H would show 4 Hearts and 0-6 Points.
            1H:2NT would be Jacoby 2nt -- 4H and Opening hand
            1H:3NT (12-15 points) would be an Opening Hand with 3 Hearts. 

Note - Using Bergen Raises a WJS can only be made at the 2-level over a major suit opening.  Also,  some partnerships have reversed their 3C and 3D meaning.