3-phase MV Booster Transformer Hookup

[J.B. Wood]

Hello, all, and after studying the following pic at
http://realneo.us/system/files/Radke-painting-on-concrete-.jpg, the
wiring doesn't seem right. There appear to be two autotransformer
boosters at either end of the mounting platform with a conventional
transformer in between. The transformer primaries are apparently wired
in delta but the secondary connections don't seem to make sense. (A
configuration of three booster transformers (one for each phase) would
seem more appropriate.) I can't seem to construct a phasor diagram of
the wiring shown in the photo and none of my EE handbooks shows anything
like this.

With these components I could connect the taps of the two boosters as
open delta then close the delta with the secondary of the conventional
transformer (assuming it has the appropriate turns ratio). But that
isn't the wiring shown in the photo. There also appears to be 4 wires
going from the transformers vice 3 wires going to the feeders at the top
of the utility poles. Your time and comment is appreciated.
--
John Wood (Code 5520) e-mail: [email protected]

Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337

 

[J. B. Wood]

To me, it just looks like a delta-delta transformer bank, with the middle
transformer in a different can (different mfg or whatever) than the other
two. It's not completely clear since not all the connections are visible
(some look like the connect where they probably don't) plus the top is cut
off.wo

Thanks for the prompt reply, Michael. I studied the photo further by
zooming in and I think you are correct in that it is a delta-delta
configuration. These aren't booster (auto) transformers at all and the
photo angle obscures two of the terminals on the tops of the leftmost
and rightmost transformers. Sincerely,

 

[Guest]

To me, it just looks like a delta-delta transformer bank, with the middle
transformer in a different can (different mfg or whatever) than the other
two. It's not completely clear since not all the connections are visible
(some look like the connect where they probably don't) plus the top is cut
off.

There are two terminals hidden by others so this confuses the picture-
agreed it is delta delta
There are two thicknesses of wire.

 

[J.B. Wood]

Was this some problem you were trying to solve or were you just
studying the wiring to try to figure out how everything was wired together
and made an incorrect conclusion? Is this some location near you or
just a random photograph found on the web or something?

Just curious (I sometimes study transformer banks myself out of idle
curiosity)

Hello, Michael, and it was an accidental discovery while Googling for
something else and it caught my (engineering) attention. I should've
taken that second look earlier instead of wasting so much time on it. I
have no idea where the photo was taken. Sincerely,

--
John Wood (Code 5520) e-mail: [email protected]

Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337