Removing neutral from transfromer's primary

[aabidalkareemLQZZW]

Hi, 

I'm struggling with removing the neutral on a branch circuit that is powering transformer's primary. 

I can't find a way to tell revit to not specify a neutral on the primary side of a transformer. 

Any help is much appreciated. 

Thank you 

[vladimir_klunduk]

@aabidalkareemLQZZW 

Solution for such issues was in this topic

https://forums.autodesk.com/t5/revit-mep-forum/how-to-eliminate-neutral-from-wire-size-in-panel-sche...

[aabidalkareemLQZZW]

I tried it, and it didn't work on revit 2024. 

[vladimir_klunduk]

Did you try to delete electric circuit that feeds the transformer and then recreate it with the new wire settings?

[aabidalkareemLQZZW]

Yes I did on revit 2024. Its not working. 

[fabiosato]

Hello,

It seems to be a bug.

[sragan]

It works for me.   Make the supply breaker larger (400A instead of 20A) so you don't confuse the neutral with the ground.

When I use the standard wiring, I get (3) 600's, (1) 600 neutral, and  #3 ground.

With the 3 phase/no neutral wiring, I get (3) 600's, and #3 ground.

Edit;  That's on 2024.3, and my transformer connector is a balanced connector, not an unbalanced one someone in the other thread said was required.

[aabidalkareemLQZZW]

Hi, Thank you for your reply. 

when the load on the secondary of the transformer is balanced perfectly, and only then, the neutral on the primary will be removed. In reality however, the load is not perfectly balanced between the three phases on the secondary, hence the neutral will be resized on the primary of the transformer. 

I have to manually make the loads on the each phase exactly the same, which means losing or adding some dummy load. 

[sragan]

I'm seeing the same thing.

There are also the distribution systems that can be set in the electrical settings.  And I even tried making a 3 phase, 3 wire, 480V delta system and using that.  But the neutral still remains for unbalanced loads.  Even if the upstream panel distribution setting is made to be 480V, 3 wire delta.  

It makes me wonder if Revit understands how delta-wye transformers work at all.  In other words, I'm not sure I trust the loads shown on an upstream panel if the transformer isn't evenly loaded.

[aabidalkareemLQZZW]

I think revit treats the unbalanced load conductor sizes on the secondary of the transformer the same way it treats the unbalanced load on the primary side of the transformer. 

I don't know what the point of setting a distribution system and classifying it as "Delta" 3-wire if revit stills shows a neutral for that distribution system.