Can i use Delta-Delta trx with Wye source?

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solarBolt

Member
Location
California
Occupation
Electrical contractor
Here is the deal,
I have 3 transformers 480-240/120 Delta to Delta.
Main board is 1200A 480/277 Wye. Breakers are each 400A 480V (not 480/277V, actually i beleive they are rate to 600V anyway).
Q: can i connect from 480V Wye source to 480V Delta incoming at a transformer above directly? Voltages work, i was just going to skip N at first and add N to 240/120V delta outgoing as center tap.
Our main loads will be 240V 1ph (we'll balance them in subpanels), the 120V is only for service outlets (no permanent draw).
All equipment is in place already.
Thanks for the help !
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
Agreed that you can use a wye source to supply delta:delta transformers.

Edited to remove a misread. I thought you were serving mostly 120V loads, but with mostly 240V loads it sounds like a good setup.

-Jon
 

solarBolt

Member
Location
California
Occupation
Electrical contractor
Thanks guys!

Do you think i'll have an issue with inspector due to introducing another Neutral to entire system? Or i guess it should be fine as it is isolated by a transformer anyway, right?
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Thanks guys!

Do you think i'll have an issue with inspector due to introducing another Neutral to entire system? Or i guess it should be fine as it is isolated by a transformer anyway, right?
The primary of the transformer has no need for the neutral connection, it does not have any neutral (single phase) loads on the primary side. On the secondary you are creating a "Separately Derived System" so as was said, you establish a new neutral and bonding point at that transformer secondary.
 
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