Issues?

[zooby]

Morning. First...If this is not legible please let me know. I will try again. I am getting a bit turned with the two different transfer switches. It seems right but thought I would throw it out here. Thanks---Doug

 

[Little Bill]

It's a might small and blurry.

 

[Bluetick21]

It's a might small and blurry.

Thanks…I’ll try again.

 

[augie47]

Bill is old and half blind... unlike some of us spring chickens.,,,
I almost made it out but a more clear copy would be better
What is the issue.....
Seemingly the bonding of the alternate source.. is the neutral switched by the transfer switch ?
That will determine the N-G bonding.

 

[ron]

As Augie asked, is the question about the N-G bonds, or maybe that ATS#1 will need to be service rated (with a main disconnect on the utility side)?

ATS#2 seems to be connected to an existing feeder on the Normal side, is it bonded upstream?

 

[hillbilly1]

Try using CamScanner, it can usually make the image sharper. It’s a free app. You can then save it as a picture so you don’t have to pay for the pdf upgrade.

 

[zooby]

I hope this will help. We are not backing up entire building here. Just what "someone" deemed necessary. ATS-2 is an existing separate structure. There is supposed to be a ground ring. Our 'south' loop 13,200 is having the transformer added into it for the new building. So to the point....yes I am asking if issues are noticed with any NG items. Thank you guys for your patience.

 

[augie47]

A lot better picture !
To me, it presented new challenges.
Is the main transformer a utility (service transformer) or facility SDS ?
I can't see any reason for there not to be OCP ahead of or incorporated in ATS-1... If there is OCP is it ahead of ATS-1 or part of ATS-1
Are the neutrals switched by the ATSs
Is there OCP ahead of ATS-2 on tbe T-9 supply ?

 

[zooby]

A lot better picture !
To me, it presented new challenges.
Is the main transformer a utility (service transformer) or facility SDS ?
I can't see any reason for there not to be OCP ahead of or incorporated in ATS-1... If there is OCP is it ahead of ATS-1 or part of ATS-1
Are the neutrals switched by the ATSs
Is there OCP ahead of ATS-2 on tbe T-9 supply ?

1- we own all transformers- but not sure if that's the answer to the question
2-if that ocp is not shown here i seriously doubt one is planned.
3-i saw in a different area that the neutral is "solid" i think that's how it was described.
4-no. i am pretty certain this comes right from the T9 xfmr. I wish my time here was spent on big picture / long term issues but that is not how it is. also being a non profit always has an impact with how the money gets spent. If someone is a lil chilly or too warm- omg lets spend $$$$ on hvac crap but electrical.............when sparks and arcs occur-we'll take a look. rant over!

 

[augie47]

It's a bit difficult to decipher without the proper OCP but basically IF you have solid neutral ATS there would be no neutral-grounding bond other than your transformer secondaries and that bond would be at the location of your grounding electrode connection,.
Now that you have a more legible diagram hopefully others will chime in....

 

[synchro]

When both ATS's are in the "normal" position there shouldn't be an issue with adverse currents through EGC's because any load current drawn through a feeder neutral conductor will be supplied by its own transformer.

However, when the ATS's are in the "emergency" position, there will be some current through the EGC's of both feeders because the two ATS's each have a N/G bond and are fed by a common generator. The parallel path that is across the neutral conductor of one of the two feeder's from the generator must pass through the EGC's of both feeders and also the neutral of the other feeder. And so the impedance of that path will be quite a bit higher than the direct path through the feeder neutral conductor connected to the generator. But there will still be some current on the EGC's.

 

[jim dungar]

When both ATS's are in the "normal" position there shouldn't be an issue with adverse currents through EGC's because any load current drawn through a feeder neutral conductor will be supplied by its own transformer.

However, when the ATS's are in the "emergency" position, there will be some current through the EGC's of both feeders because the two ATS's each have a N/G bond and are fed by a common generator. The parallel path that is across the neutral conductor of one of the two feeder's from the generator must pass through the EGC's of both feeders and also the neutral of the other feeder. And so the impedance of that path will be quite a bit higher than the direct path through the feeder neutral conductor connected to the generator. But there will still be some current on the EGC's.

This current can affect Ground Fault protection resulting in early or late tripping.