You need to provide more details.When installing a HRG to a 3-phase 4-wire wye transformer (existing transformer) would it be correct to say that the system is not a solidily grounded system, thereby requiring the existing grounded conductors be removed?
Rick
After rereading your OP, I am now under the impression that you are converting an existing 4-wire secondary into a 3-wire HRG. Yes, you are creating a system that is no longer solidly grounded.
Jon is correct, you must remove all existing L-N loads. Personally, I would 'safe off' any existing grounded conductors, so that they are not mistaken as being still in service.
Technically there is no reason for them to have any specific line-load, practically, however, most commercially available ones do. This is probably because of ancillary components like current sensors and pulsing contactors.Do the grounding impedance's have a line/load for lack of the proper terminoligy, or can they be connected to either/or end. In other words can they be flipped 180deg and still work as they should. Thank You.