ECN Forum Forums Photo Discussion Forums Photos for General Discussion Old delta-delta xfmr bank

Scott35's transformer pictures spark the memory of one version of utility-supplied three-wire delta service I found at a pretzel plant in El Segundo, CA {north of Disneyland ~15 miles.} The building had an original 800A 240V 3ø 3-wire corner-grounded-delta service, with several drytype 1ø transformers for 120/240V 1ø 3-wire feeding lighting and 120V convenience outlets. More recently, a 400A 120/240V 1ø 3-wire service had been added. The plant’s maintenance crew did onsite electrical troubleshooting, and some were very confused by the two different grounded-circuit conductors {all correctly white} that had completely different voltage relationships. In many places in the plant, they found circuits with 240V to ground, and in other places 120V to ground, but with no distinct phase/color-coding or markings to readily differentiate the different systems.

At the end of two weeks of training to understand their electrical system and work on it safely, out of a crew of about 8, a couple of guys understood it and were committed to teach others what to expect, and why the plant has more that one set “neutral” conductors. In corner-grounded-delta circuits the “white wires”/grounded-circuit conductors were not neutrals by Code definition, but “white wires”/grounded-circuit conductors in 120/240V circuits are. To complicate matters even more, the corner-grounded 3ø system used some 2-pole fusible switches, and both two- AND three-pole circuit breakers.

[The plant’s 1ø and 3ø transformers were served by once regionally popular 4800V 3ø ungrounded-delta distribution.]




[This message has been edited by Bjarney (edited 02-21-2004).]

Scott 35
I stumbled (usual mode of travel) across that xfrmr bank, and it's next to the Bank, and right around the corner from my house.
Oh, great! Now I'll get this endless addiction to taking pictures of powerlines and transformers.
(You know, my whole street is going overhead to underground right now. Time to shoot pics).

May be time to start "Electricians Anonymous?"
...S


[This message has been edited by electure (edited 02-24-2004).]

Paul;


You're welcome! Glad to be part of the discussion.


I have seen a bunch of Polyphase Transformers for pole mount around these parts, similar to the one you have posted. Only the enclosures are a bit different in appearance, plus the H.V. Bushings normally are mounted on the top and the L.V. Bushings are on the front.

Bjarney;


Ya, the center one is huge, as compared to the outer two Transformers. It also has the cooling tubes, whereas the others do not have these.


Thanks for the linked items! Added them to my ever-increasing Library 'O Info.


Electure;


DING!!! Give the Man a Cigar!
I have been in this building a few times. Last time was to install a Card Reader Entry system at the side door, and also do an ATM upgrade (survey, design, install).


You're Wife is really going to be puzzled now!
My Wife still laughs about it - like the times we pull over suddenly and out comes the Digi Camera - aimed at Power Lines / Equipment!
She used to joke about this stuff + the "stalking trains" stuff, but it happens so often it lost all humor to her!


I was wondering what was going on in your area! Wonder if our area is on the list too?
Street renovation is taking place currently. City workers have been patching like mad (smell of tar everywhere). Resurfacing is set for June.



In the words of "Duff Man"...
"Ohhh, Yaaahhhhh!!!"

Scott35