Corner Grounded Delta Utility to a Service Entance Rated ATS

[Shujinko]

In one of my electrical designs for an existing dock, I have an existing utility service transformer 4160V delta pri - 480V delta sec, corner grounded delta. This is going to feed a service entrance rated automatic transfer switch (ATS) which will in turn feed a motor control center. What would I have to specify for the ATS if the service lateral from the utility transformer is 480V, 3-phase, 3-wire corner grounded delta? Would I need to specify a 3-pole ATS switch and switch all the phase conductors, what would happen with the neutral lug of the ATS? Or would I use a 2-pole transfer switch and not switch the grounded leg of the system, in this case where would I land the the B-phase (corner ground) of the system?

 

[templdl]

In one of my electrical designs for an existing dock, I have an existing utility service transformer 4160V delta pri - 480V delta sec, corner grounded delta. This is going to feed a service entrance rated automatic transfer switch (ATS) which will in turn feed a motor control center. What would I have to specify for the ATS if the service lateral from the utility transformer is 480V, 3-phase, 3-wire corner grounded delta? Would I need to specify a 3-pole ATS switch and switch all the phase conductors, what would happen with the neutral lug of the ATS? Or would I use a 2-pole transfer switch and not switch the grounded leg of the system, in this case where would I land the the B-phase (corner ground) of the system?

With the limited information as provide as a manufactured I would quote a basic 3p 480v ATC with ground to include any bells and whistles (options) as may be required. I prefer a breaker type ATS but a contactor type may be provided also such as an ASCO understanding that it is not SE. Remember that a breaker type ATS can provide certain protective features that a contactor type can not.
It is also important to not that a contactor ATS may not be desirable because the transfer speed may be to fast because it may cause a slight out if phase transfer condition which OCPDs often do no like very much and trip.
As a former manufacture's sales and applications engineer I like to ask a lot of questions to assure that my product is applied properly.
A breaker type ATS is often avsilable with an SE label as an option if required.

 

[Shujinko]

With the limited information as provide as a manufactured I would quote a basic 3p 480v ATC with ground to include any bells and whistles (options) as may be required. I prefer a breaker type ATS but a contactor type may be provided also such as an ASCO understanding that it is not SE. Remember that a breaker type ATS can provide certain protective features that a contactor type can not.
It is also important to not that a contactor ATS may not be desirable because the transfer speed may be to fast because it may cause a slight out if phase transfer condition which OCPDs often do no like very much and trip.
As a former manufacture's sales and applications engineer I like to ask a lot of questions to assure that my product is applied properly.
A breaker type ATS is often avsilable with an SE label as an option if required.

So if I do specify a 480V, 3pole ATS, there would be no neutral in this system so would there just not be any conductor connected to the neutral lug in the ATS or would there not even be a neutral lug provided? Also, since the utility transformer feeding the normal side of the ATS is a 480V delta corner grounded system would this mean the phase B (corner ground) be switched and then the emergency generator need to be considered a separately derived system since phase B is shared with the grounded leg and in essence you are switching the ground?