Ground Fault Detection of a Delta/Delta transformer
Ground Fault Detection of a Delta/Delta transformer
(OP)
Look for some advice on adding secondary GF protection on a 4000KVA 13.8/4.16KV transformer. Does anyone have a link which explains my options or can anyone give some advice?






RE: Ground Fault Detection of a Delta/Delta transformer
What is the 4kV system-grounding method—ungrounded/solid/high-resistance/low-resistance?
Start with IEEE Std 142 §1.
RE: Ground Fault Detection of a Delta/Delta transformer
RE: Ground Fault Detection of a Delta/Delta transformer
RE: Ground Fault Detection of a Delta/Delta transformer
The voltage across the corner will be 3Vo.
See any relaying text, such as Blackburn's "Protective Relaying".
RE: Ground Fault Detection of a Delta/Delta transformer
RE: Ground Fault Detection of a Delta/Delta transformer
To add to dpc’s comments, the transformer primaries, although normally exposed to ø-n voltage, must be rated for full ø-ø voltage—id est, 35:1 [not 20:1] for this application.
Chapter 6 of Beeman’s IPSH (circa 1955) has a very lucid description of the potential problem. It is very real—with tragically expensive results at 480/600V, murder at 4160V, and mass suicide at 12kV.
RE: Ground Fault Detection of a Delta/Delta transformer
So they are still around, in spite of the conventional wisdom that they are a problem.
RE: Ground Fault Detection of a Delta/Delta transformer
Here is one of the links..
http://www.byramlabs.com/pdf/basler/ubg7bull.pdf
RE: Ground Fault Detection of a Delta/Delta transformer
If switchgear/motor/cable-run/transformer conditions have been kept consistently sanitary, and winding insulation has no 'weak spots,' it is possible for ungrounded systems to operate successfully, but practically, that is the exception to the general case.
Surge capacitors can be their own double-edged swords.
RE: Ground Fault Detection of a Delta/Delta transformer