Zig Zag gounding xfmr for 100KW ground mount array

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Giark

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Location
Eugene, Oregon
The utility is requiring a zig zag grounding xfmr for a 100kw ground mounted array. I have xfmr sizing from them. I know there is a protective relay required to make this setup work. I imagine there are a variety for ways to accomplish this. In hopes of not reinventing the wheel does anyone have a preferred method/ components that work? Thanks, John
 
The utility is requiring a zig zag grounding xfmr for a 100kw ground mounted array. I have xfmr sizing from them. I know there is a protective relay required to make this setup work. I imagine there are a variety for ways to accomplish this. In hopes of not reinventing the wheel does anyone have a preferred method/ components that work? Thanks, John

Interesting. I dont quite follow though. Where is the zig zag to go? Is there already an ungrounded service supplying the site that this will be tied into?
 

GoldDigger

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Staff member
Location
Placerville, CA, USA
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Retired PV System Designer
There is another thread about a POCO which is requiring a zig-zag grounding transformer even though the service itself is a grounded wye. There was never a good engineering explanation for that requirement.
 

jim dungar

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Staff member
Location
Wisconsin
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PE (Retired) - Power Systems
There is another thread about a POCO which is requiring a zig-zag grounding transformer even though the service itself is a grounded wye. There was never a good engineering explanation for that requirement.

Most of the time, the issue involves the 'distributed generator' becoming 'islanded' from the utility grounded-wye system.


Generically the term is 'artificial neutral'. A Zig-Zag is simply one style of 'grounding transformer',another common one is often called a 'wye-delta'.
Impedance grounding, like HRG, is a separate issue from providing a ground reference.
 

GoldDigger

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Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Most of the time, the issue involves the 'distributed generator' becoming 'islanded' from the utility grounded-wye system.

Which was somewhat odd given that the distributed generation in question was a grid tie inverter array which automatically shuts down when islanded.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
Which was somewhat odd given that the distributed generation in question was a grid tie inverter array which automatically shuts down when islanded.

Are you saying someone didn't look at all the details before making a judgement?:blink:
 

excel

New member
Solution for Effective Grounding

Solution for Effective Grounding

The utility is requiring a zig zag grounding xfmr for a 100kw ground mounted array. I have xfmr sizing from them. I know there is a protective relay required to make this setup work. I imagine there are a variety for ways to accomplish this. In hopes of not reinventing the wheel does anyone have a preferred method/ components that work? Thanks, John

Hello Giark, I have a following solution which you might like to use for this application.
See if it make sense for you.

Image 1.jpg image 2.jpg
 
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