Re: Large transformer available

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "J. Aaron Holmes" <jaholmes@xxxxxxxxxxxxxxxxxx>

Some of the more rural substations where I live use
three single-phase transformers instead of one large
three-phase transformer, probably because transporting
a very large three-phase transformer to those remote
places is not possible.  Now, one of *those* would be
really cool to have!  You could power it in two
stages, using a large pig to step your home current up
to the voltage needed to feed the substation
transformer.

I'd be interested to find out (or compute) how much
power it would take to get anything out of a multi-MVA
transformer, though.  Think of what it would take just
to magnetize all those tons of metal!

---

Around here, most distribution substations are
delta-fed at 115kV.  Curiously, the substations I see
that use three single-phase transformers have the HV
sides wye-connected, but since the 115kV feed is
delta, the neutral is left floating.  Is that common
practice?  Seems kind of scary to me, but I'm not a
power engineer.  Obviously this enables use of cheaper
69kV transformers...  I'd always heard that you could
feed a delta load with wye (leave the neutral
unconnected), but not the other way around, as would
seem to be the case here, because of the imbalance
that might result.

--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: "Dave Halliday" <dh@xxxxxxxxxxxxxx>
>
> I was reading the Mostly Cajun blog (he is an
> industrial electrician)
> and ran into this post:
>
> http://mostlycajun.com/wordpress/?p=1575
>
> 34.5kV Substation transformer just shy of 50 tons
> (98,800 pounds weight)
>
> Now __that__ would make a nice large coil...
>
>
>