Wye Wye

[ptonsparky]

What happens or are the side affects of a Delta-Wye transformer that is connected to a wye primary? Three wires of the 480/277 primary. No neutral connection.

Another post lead me to think this was not a good idea and left me with unanswered questions.

 

[frenchelectrican]

i think there is a sideeffect or two.

the current balanceing get tricky it not the same as normal run of mill delta primary side and also IIRC that it do shift the phase to some degrees i think about 30? or so

also with WYE primary side if primary side is true wye connected the curciration current kinda dissapair if my theroy is correct, but if you loose one leg on wye primary IIRC it will really seriousally derated the performaic down to 57% of the transformer rating

Merci, Marc

P.S. i think this item will crop up as well someone mention that to me that with 3 core transformer conferaged for wye -wye saying about the ferrioumous [ sp ] loss but i am not sure if this info is correct

 

[drbond24]

I called Square D's technical support and asked about this. They said there was absolutely no problem at all with connecting 3 wire wye to a delta primary transformer. I asked for details but was pretty much told it works exactly the same. The transformer doesn't know the source is wye because you don't give it the neutral, so it does it's job the same as always.

I was the one in the other post that said I didn't think this would work, so I'm going to go correct myself there now.

 

[ptonsparky]

Thank you, I had never worried about it before and have hooked up more than a few. Guess my eyes were crossed when I read the post.

 

[micromind]

There are literally thousands of delta xfmrs connected to wye systems. I've done maybe a hundred or so myself.

The biggest reason these xfmrs are delta-wye and not wye-wye is because a delta connection, by it's very nature, tends to balance voltage, where a wye does not. Plus, you only need 3 wires to feed it, not 4. (Plus a ground).