Delta on a Wye system
Delta on a Wye system
(OP)
What are the ramifications of connecting a delta transformer to a grounded wye system?
Available primary is 12,470 GrdY/7200. The 3 phase padmount is 12,470 delta.
Secondary is 120/240 delta with one grounded leg.
The voltages are correct and the transformer will work. I am concerned about other areas like safety, backfeeds, fault scenarios, switching, etc.
All other padmounts and overhead banks are grounded wye.
Thanks for any input.
Bob
Available primary is 12,470 GrdY/7200. The 3 phase padmount is 12,470 delta.
Secondary is 120/240 delta with one grounded leg.
The voltages are correct and the transformer will work. I am concerned about other areas like safety, backfeeds, fault scenarios, switching, etc.
All other padmounts and overhead banks are grounded wye.
Thanks for any input.
Bob






RE: Delta on a Wye system
This sounds like a utility distribution feeder?
RE: Delta on a Wye system
You are correct, distribution feeder.
Waross,
Almost correct, the secondaries will yield 120 ph-gd and 240 ph-ph on the leg with the center tap grounded.
I am mostly concerned with primary side issues.
Thanks for the feedback, guys.
Bob
RE: Delta on a Wye system
RE: Delta on a Wye system
Bob
RE: Delta on a Wye system
B
RE: Delta on a Wye system
RE: Delta on a Wye system
In a delta:wye, line to ground fault current on the secondary will be seen as line to line current on the primary.
It may make a difference to your protection planning or awareness if you add a delta:wye transformer to a predominantly wye:wye system.
Then again it may not make any difference at all.
Bill
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"Why not the best?"
Jimmy Carter
RE: Delta on a Wye system
If that is not possible use a three phase device to protect the primary cable system like a recloser or sectionalizer.
The ferroresonence occurs when one cable fuse blows or when the worker closes in one fuse.
Another solution would be to add load to the secondary of the transformer, such as a load box, when closing in the fuses.
RE: Delta on a Wye system
B