help with transformer nameplate

[aksparky]

I have been studying several of the subjects I lack knowledge in, and one of them is transformers.
I have a book on transformers Im going thru and always look at the nameplate ratings on them when I get the chance.
I came across one today that feeds 2 dwelling units and a shop all with single phase power that is supplied by the utility company.
the nameplate reads
37.5kva 2% imp
12470GRDY/7200 primary
240/120 secondary
1- In a wye system, phase volt * 1.732 = line volts So Im guessing thats the primary 7200*1.732=12470?
2-Is it a common or standard that utility use 3phase xformers to supply single phase dwellings?
3-what does the "GRDY" signify in the nameplate rating
Thanks alot for any input

 

[mdshunk]

1- In a wye system, phase volt * 1.732 = line volts So Im guessing thats the primary 7200*1.732=12470?

Yes, you're exactly right.

2-Is it a common or standard that utility use 3phase xformers to supply single phase dwellings?

Only for services in congested areas, which we call "network services". Nothing on your dataplate indicates this is a 3-phase transformer anyhow. I'm about 99% sure it's fed single phase.

3-what does the "GRDY" signify in the nameplate rating
Thanks alot for any input

Grounded Wye.

 

[aksparky]

Thank you for the reply and the info Marc,
I guess what Im having a hard time understanding is how could the primary be
12470/7200 and only be single phase? I must be missing the big picture.

 

[mdshunk]

Thank you for the reply and the info Marc,
I guess what Im having a hard time understanding is how could the primary be
12470/7200 and only be single phase? I must be missing the big picture.

In your case, the spec if from a regular one-bushing pot. The 12470GNDY is the type of system it is for, and the 7200 is the primary voltage of the pot. This is pretty much the textbook pole top transformer. It's just fed with the hot and neutral from one "phase" of a 12470 wye system.

 

[aksparky]

Thanks again Marc,
I appreciate the response and that makes sense, I didnt even think of it that way. I guess theres only so many examples a book can give and as I come across these kind of things, I have a hard time moving on till I know what Im missing. Again, thanks for the help and the info.