Transformers Question

If I understand your question, the answer is "No". You have to have the correct phase rotation to the load. Otherwise, 3 phase motors will turn backward.

I assume you are talking about the markings on the transformer bushings, and not the phase relationship throughout the plant.

A single unit transformer, (not paralleled with another transformer), does not care about phase rotation. It will send the power through as it receives it.

If you connect the transformer markings reversed on the primary, and they end up reversed on the secondary (as we would expect of a standard unit), it will work fine. Just follow the system phasing through the transformer, generator phase 1 connects through transformer to phase 1 of switchyard transmission bus.

When it comes to generator transformers, it doesn't matter if two terminals are interchanged, as the generator phase matching will ensure synchronising can still be done.

However, the problem could arise at the auxiliary switchboard level, if the auxiliary switchboards are supplied from the generator terminals and the two auxiliary switchboards have a tie feeder.

So, ensure that the generator transformer vector group test is done and the winding connections are identical for both the transformers.