New Transformer Grounding
New Transformer Grounding
(OP)
Hi All,
I am seeking a logical explanation for a new transformer grounding. It is Pig/Hog processing facility and the owner is planning an expansion. I am new to this world of industrial installations and I am sure you guys have seen and done it all.
They plan to install one big 66 kV/13.8kV 10MVA transformer.
and then four small progressive addition of 2 MVA transformers being fed from big one. I am sure the local utility will advise the transformer configuration.
In a typical world, what you guys would see: Here is what I think:
1. 66 kV/13.8 kV Delta/Star Low Res. grounded
and then those 2 MVA 13.8kV/600 V shall be Delta/Y solidly grounded or low res. grounded.
Could you guys kindly advise, what am I missing here or
this does not makes sense to you. I know all types of grounding it is just that I have not seen to much in these few years of experience so a suggestion would certainly help.
I am seeking a logical explanation for a new transformer grounding. It is Pig/Hog processing facility and the owner is planning an expansion. I am new to this world of industrial installations and I am sure you guys have seen and done it all.
They plan to install one big 66 kV/13.8kV 10MVA transformer.
and then four small progressive addition of 2 MVA transformers being fed from big one. I am sure the local utility will advise the transformer configuration.
In a typical world, what you guys would see: Here is what I think:
1. 66 kV/13.8 kV Delta/Star Low Res. grounded
and then those 2 MVA 13.8kV/600 V shall be Delta/Y solidly grounded or low res. grounded.
Could you guys kindly advise, what am I missing here or
this does not makes sense to you. I know all types of grounding it is just that I have not seen to much in these few years of experience so a suggestion would certainly help.






RE: New Transformer Grounding
It seems OK, .
For the more information, please see greenbook.
http://s
Best Regards.
Slava
RE: New Transformer Grounding
Thanks Slavag. I have read Green book and that is where I understood the idea of grounding.
My question is more related to the tradition in industrial and processing facilities.
Recently, I was working on an arc flash study of a casion and I noticed that they have 2 MVA 13.8kV/600 V transformer and the ground fault current on the secondary of the transformers is in 20 kA. So I was wondering, why dont we make these sec. high or low res. grounded rather leaving them solidly grounded.
I am just looking for a basic explanation that what could be a possible reason for leaving them solidly grounded.
I would appreciate a word.
Thanks
RE: New Transformer Grounding
High-resistance grounding at 600 V or 480 V has some advantages in terms of safety and reliability, but it does impose a requirement that maintenance electricians be well-trained and diligent in tracing single ground faults. I would not make that assumption at a slaughterhouse and would lean towards the brute force approach of solid grounding.
If you want to educate yourself on grounding, I highly recommend this book:
"Industrial Power System Grounding Design Handbook" by Dunki Jacobs, Frank Shields, and Conrad St. Pierre.
Regards,
Dave
"The more the universe seems comprehensible, the more it also seems pointless." -- Steven Weinberg
RE: New Transformer Grounding
I recently bought this book. I even have personally spoken to Conrad St. pierre in NYork a while ago regarding a substation grounding issue.
I am in Canada actually.
I had never heard of the disasterous effect of low vol. grnd. on 600V or 480 V being illegal in US.
Could you kindly drop a word, what makes it so bad.
Thanks
RE: New Transformer Grounding
I don't believe it is allowed by the NEC below 1000 V.
"The more the universe seems comprehensible, the more it also seems pointless." -- Steven Weinberg
RE: New Transformer Grounding
The benefit of detection and clearing any faults as quickly as possible when on a utility source and the fact that higher fault currents allows more room for coordination favors solidly grounded systems.