tranformer 480 delta to wye question

Status
Not open for further replies.
C

cee111

Member
Hi 1st timer here.

I am currently installing a 300amp vacuum mold machine that requires a 480V four wire wye and the building has a 480V four wire wye feeding the building. The problem being is the bus does not supply me with a Neutral and the machine is about 500 feet away from where the service comes into the building from Edison. So I believe my options are 1.Pipe the service from the machine to a 480V Breaker (500ft away) so I can find my neutral there,
or use an isolation transformer 480 to 480. Since the building is fed with 480 / 277volts to ground wye.

Can I use a 480/480 isolation delta to wye transformer here??

If I am missing something Or if there is a better way of doing this please let me know. thanks
 
cee111 said:
Hi 1st timer here.
Click to expand...
Welcome to the forum.
cee111 said:
Can I use a 480/480 isolation delta to wye transformer here??
Click to expand...
Yes you can. It sounds like your best bet. But you might want to do a quick and dirty cost comparison. A long run of conduit and wire has a price. A couple shorter runs, plus a transformer and its housekeeping pad, plus perhaps a new disconnect switch, plus the additional HVAC considerations that arise because of the heat generated by the transformer, will collectively have a price as well. Which is cheaper? You'd have to crunch the numbers to be certain.
 
Would it be possible to derive a neutral using a zig-zag transformer or some sort of autotransformer, rather than using a 250KVA transformer? This would not be an SDS, so you wouldn't need a new GEC, and only a fraction of the load would pass through the transformer, so it would be smaller.

It seems like a nice theory, but I don't know the legalities or if there would be subtle problems to be expected (neutral to ground voltage issues, problems with harmonics, etc.)

-Jon

P.S. Welcome to the forum. Just so you know when I pop up with crazy ideas: I am a motor theory guy, not an electrician or a PE.
 
What exactly are they using the neutral for? Is there a lot of 277 volt loads being feed from this? If there is not a large amount, think about a 480 to 277 single phase transformer if the 277 volt loads can be split out easily.
 
hillbilly1 said:
What exactly are they using the neutral for? Is there a lot of 277 volt loads being feed from this? If there is not a large amount, think about a 480 to 277 single phase transformer if the 277 volt loads can be split out easily.
Click to expand...
Yes, I was going to suggest something like that.
Most three phase loads don't need a nuetral.
Oh, and welcome cee111 !
 
sorry guys was out of town. There is no print for the machine but there is a neutral bar with about twenty gray wires on it. Was thinking maybe the heating elements are V???? I have never seen V on anything but lights. Was curious so I bonded the neutral to the building steel to see if there was any current flowing through the neutral. Clamped on a meter and there was between 40 and 100 amps of current . That scares me to see that much current.

The zig zag is interesting. Has anyone ever used one in a similar application?

thanks for the replies
 
Status
Not open for further replies.
Top