Delta Y dry transformer

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dave1

New member
Location
Boise, Idaho
I have a client that has an existing delta Y dry transformer that he wants to connect to a 480/277 Y service to get 208/120. will this cause any problems
 

templdl

Senior Member
Location
Wisconsin
I have a client that has an existing delta Y dry transformer that he wants to connect to a 480/277 Y service to get 208/120. will this cause any problems

Please advise what the nameplate of the transformer isd. Or, attach a picture of the name plate.
Off hand if I were to guess there shouldn't be a issue. But I would feel alot more comfortable in knowing what the transformer in question is first.
 

kwired

Electron manager
Location
NE Nebraska
Probably one of the most popular transformer configurations out there is 480 delta to 208/120 Y, but you also need to know details on the load served, available capacity from the source and VA rating of the unit to be selected at a minimum.
 

dema

Senior Member
Location
Indiana
It is common to use a delta wye transformer on a 277/480V wye source. You take three wires over to the transformer plus ground. You pick up a new neutral on the secondary side. This configuration is called separately derived and is the most common way of doing tings. Be sure to size wires and OCP correctly and to follow manufacturer's grounding instructions (and the NEC.) If the transformer isn't sized appropriately for what is being done, there could be issues. Example, if you put a 300KVA transformer in where you needed a 45KVA transformer, there could be issues such as excess heat, tripping the breaker even though there is very little load, lost efficiency and so forth.
 

junkhound

Senior Member
Location
Renton, WA
Occupation
EE, power electronics specialty
To OP: Also find and read the recent threads on harmonics. If there are a lot of harmonic producing loads on the 120 lines, you can burn out your 480 delta primary.
 
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