Corner grounded delta 3phase transformer?

Status
Not open for further replies.
Sorry for the late reply. I was in the field until late.

Can you give me the info to find such a transformer?
 
The main disconnect for the corner grounded delta 3phase is 800amp. Once this goes thru the transformer how many 1phase amps will be available?
 
What voltage is the corner grounded system? What other loads are on it? Can you give us more details on what you are trying to do?.
 
240vt / 240vt / 0vt

The system is currently not in use. All 800amps on this 3phase corner grounded delta are available. They want to use it as 1phase.
 
The easiest would be to use a 240 delta to 120/208Y transformer. I think the largest standard size transformer that you could use with an 800 amp source would be a 225 kva. The full load primary amps would be 542 and the secondary full load current would be 625 amps.
You could also use three 240 to 120 single phase transformers.
What are the 120 volt loads?
 
Last edited:
The 120vt loads will be normal office needs such as lights, refrigerators, computers, etc. There will also be some HVAC running on 240vt.

It is a warehouse conversion to loft office. The building was originally fitted with the 3phase system and a very small 1phase.
 
Unless one of our most learned engineer folks speaks up here, you might want to discuss with an engineer the possibility of adding some transformers in a zig-zag fashion.
I am not smart enough to provide you with the details, but as best I recall I have seen such an arrangement to generate neutral from a delta source and the transformers are wired in an auto transformer manner so the sizes are relatively small compared to a full dealt-wye unit.
 
augie47 said:
Unless one of our most learned engineer folks speaks up here, you might want to discuss with an engineer the possibility of adding some transformers in a zig-zag fashion.
I am not smart enough to provide you with the details, but as best I recall I have seen such an arrangement to generate neutral from a delta source and the transformers are wired in an auto transformer manner so the sizes are relatively small compared to a full dealt-wye unit.
Click to expand...
I could be wrong, but I believe that zig-zag has very little capacity for line to neutral loads. Also, I don't think you can use it with grounded supply system.
 
don_resqcapt19 said:
I could be wrong, but I believe that zig-zag has very little capacity for line to neutral loads. Also, I don't think you can use it with grounded supply system.
Click to expand...

I would yield to your knowledge. My memory to those installs where I saw the zig-zag is fuzzy... heck my memory of yesterday is fuzzy :D.. but I thought it might be worth running by an engineer.
 
Yes, zig-zag transformers can be implemented to create a neutral point that is able to carry substantial load current. The problem is the original system is 240V L-L, therefore the zig-zag will create a 139V L-N.


My suggestion would be (1) panel to serve 240V L-L loads and a different panel, fed by a 240:208Y/120 transformer, for 120V L-N loads.
 
Status
Not open for further replies.
Top