generator step-up transformer?

[pajce]

is it possible to have delta (or ungrounded wye)winding configuration on primary of the generator step up transformer (higher voltage side) that feeds 4 wire system?
I would think neutral is needed to feed 4 wire system (grounded or not, but neutral must be there? Am I right?
Even if this generation is tapping to Utility grid?

 

[rcw retired EE]

Pajce- It is possible to have a delta winding on the HV utility connection, even if it is a 4-wire system, but not desirable unless the system load is relatively balanced. Any phase-neutral loads will essentially be carried by the utility and not this generator.

The delta makes it more difficult to detect phase-to-ground faults and coordinate protection.

On the plus side, adding the generator will have minimal effect on the system's ground fault current levels. On two power plants we built, the utility required delta windings to keep from increasing their systems' ground fault levels which would have led to excessive GPR and safety problems at adjacent substations.