TRANSFORMER INSTALL

[ROBERT GANDARILLA]

My question is that we have to get a new tranformer to feed a 240 volt 3 phase machine, and the voltage available is 480 volt system without high leg that I think is a Wye system. I need someone to help me figure out how to pick out the right transformer, what I know is that if I have a 480 Wye system I need a transformer to be 480 Wye on the primary, and it depends on what voltage that I want on the secondary. Can somebody help me or let me know if I am right or wrong? Thanks for your help.

 

[augie47]

a 480 (primary) to 240 or 208 secondary will work on either a 480 Wye or 480 Delta system.
If it's 480 Wye simply ignore the neutral.

 

[ROBERT GANDARILLA]

I got it thanks for your help.

 

[texie]

My question is that we have to get a new tranformer to feed a 240 volt 3 phase machine, and the voltage available is 480 volt system without high leg that I think is a Wye system. I need someone to help me figure out how to pick out the right transformer, what I know is that if I have a 480 Wye system I need a transformer to be 480 Wye on the primary, and it depends on what voltage that I want on the secondary. Can somebody help me or let me know if I am right or wrong? Thanks for your help.

Hopefully your new machine is OK with 208 volt, then you can just use a standard off the shelf 480 delta primary X 120/208 wye secondary transformer of the appropriate size. As Augie said, you don't need orwant a neutral on the primary side. Just keep in mind all the grounding and bonding requirements. If you have to have 240 volt/3 phase that will be another story.

 

[jim dungar]

...what I know is that if I have a 480 Wye system I need a transformer to be 480 Wye on the primary,....

No, you do not.
Delta connected transformers are connected to wye sources, in maybe 99.99% of installations.

Get a standard 480V delta to 240/120 delta transformer. With a high-leg 4w output, you will be able to use the X4 terminal as your reference. Make your bond in the transformer and then leave with just your 3 phase conductors + ground.

 

[jumper]

Do not know what code cycle you are on, but 2011 added this.

450.14 Disconnecting Means. Transformers, other than
Class 2 or Class 3 transformers, shall have a disconnecting
means located either in sight of the transformer or in
a remote location. Where located in a remote location,
the disconnecting means shall be lockable, and the location
shall be field marked on the transformer.