ATS 3 or 4 Blade

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twayne

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Can anyone explain whether or not a 4 blade ATS is needed when an emergency generator is installed at an existing facility? The facility has a 120/208 Volt 3 phase 200 amp service.
 
It is a design choice. No rule requires it to be one way or the other. However, once you make that choice, there are rules concerning how you must wire the ATS, particularly with regard to the wiring of the equipment grounding conductors.
 
I beleive you mean 208Y/120V service?

3 or 4 pole ATS It depends on how the system is configured. Check the IEEE Orange book, Std 446 to help with proper determination.
 
Ats

Ats

Thanks for the info, have you ever heard of a transfomer with 120/208V "Delta" secondary voltage?
 
Nope!!! Not possible! Have heard of 120/240 delta secondary. In this case, one of the transformers is center tapped. If you tried to center tap a delta 208V secondary, you would only get 104 Volts!
 
Twayne,

The four pole ATS is normally used on services that have GFPE protection.

For a 200a service,I would think that a 3P ATS would be fine.
 
charlie b said:
. . . particularly with regard to the wiring of the equipment grounding conductors.
Click to expand...
Wouldn't that be the grounded conductor that has the main differences? Or, more specifically, the bonding?
 
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