Parralleling Transformers
Parralleling Transformers
(OP)
I am reviewing a project where the design contractor is intending to parallel a 30MVA , delta-Y transformer with a 30 MVA Y-delta transformer.
I think that this can't be done because of the difference in the angular displacement between the two transformer windings.
He insisted that this can be done and is taking it too high.
I appreciate any suggestions.
.
I think that this can't be done because of the difference in the angular displacement between the two transformer windings.
He insisted that this can be done and is taking it too high.
I appreciate any suggestions.
.
MMQ






RE: Parralleling Transformers
However, I would be worried about the fact that there are obviously differences in the grounding between the two transformers. Loss of one transformer could result in ungrounding part of the system, unless this is taken care of by some other means.
RE: Parralleling Transformers
The proposed may look good on paper, but needs to be proven by careful phasing checks on initial energization. There will be an inherent high-to-low-side 30° phase shift within each bank, but are both in the same direction? If not the same, change would require access to individual transformer coils, which is not likely. Added to the different grounding aspects, unbalance and fault currents, and the associated protective scheme will almost certainly change with either or both transformers in service.
I would insist on a detailed commitment from the contractor—with resolution spelled out in detail if the proposed system does not work to the end user’s contractually defined functional and safety specifications.
RE: Parralleling Transformers