Delta to Delta Transformer Grounding

[dvcraven052256]

I have to step transformer 240-480V, 3phase. I am not sure the best approach is to ground the secondary either via corner grounding or if I should order as 480/277V service to a small panel in lieu of just a 480V panel. In essence I am feeding just (2) 480V, 3phase motors rated 3 hp.

 

[jim dungar]

In my shop I would corner ground it. However if any 'general electrician' was going to work on it, I would use a 480Y/277V output, because it is a more commonly seen arrangement.

 

[infinity]

I would use a Wye secondary so that you can ground it. If VFDs are involved corner grounded might not be the best option.

 

[petersonra]

I have to step transformer 240-480V, 3phase. I am not sure the best approach is to ground the secondary either via corner grounding or if I should order as 480/277V service to a small panel in lieu of just a 480V panel. In essence I am feeding just (2) 480V, 3phase motors rated 3 hp.

I am not a huge fan of corner grounding, mostly because it is pretty uncommon these days. Plus it complicates using vfds

 

[dvcraven052256]

Thank you for your inputs. I will go with 480/277V. My electrician said he only needs 480. But for ease of the installation I was leaning toward 480/277V panel. Yes there are VFD involved.

 

[infinity]

I am not a huge fan of corner grounding, mostly because it is pretty uncommon these days. Plus it complicates using vfds

I agree and to Jim's point many sparkies are confused by it.

 

[winnie]

Joining the chorus here. Use a 240V delta to 480/277V wye step up transformer. Your VFD equipment wants 480V L-L and 277V L-G. (I say L-G not L-N because N is not a needed circuit conductor, but the parasitics to ground are relevant. )

 

[JoeStillman]

If you bond the neutral to ground at the transformer, you don't have to run it to the panel.