I was recently working in a facility which all the transformers which were originally configured in a un-grounded delta-delta which were all fed from a utility at a single point outside the plant fence. (When I mean un-grounded I mean, only three wires, one for phase A-B-C for the secondary side, with no common ground grid in the facility)
The owner recently decided to demo two of the existing transformer, replace the transformers and install two new utility taps (so three utility taps total). One of the new transformers is now a primary wye-grounded with a secondary Corner grounded delta and the other transformer a primary delta with a solidly grounded wye.
Since all the existing plant distribution feeders only has three wires to the plant distribution switchgear, one for each phase, what happens with these transformer grounds? Both of these new transformers are hundreds of feet apart with the existing transformer even further, and there is no common ground grid in the facility.
Hope I'm clear
Thanks
The owner recently decided to demo two of the existing transformer, replace the transformers and install two new utility taps (so three utility taps total). One of the new transformers is now a primary wye-grounded with a secondary Corner grounded delta and the other transformer a primary delta with a solidly grounded wye.
Since all the existing plant distribution feeders only has three wires to the plant distribution switchgear, one for each phase, what happens with these transformer grounds? Both of these new transformers are hundreds of feet apart with the existing transformer even further, and there is no common ground grid in the facility.
Hope I'm clear
Thanks
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