Loud and clear!
------ Original Message ------
From: "Dennis Miles via EV" <ev@lists.evdl.org>
To: "Robert Bruninga" <bruni...@usna.edu>; "Electric Vehicle Discussion
List" <ev@lists.evdl.org>
Sent: 25-Jun-14 10:59:15 PM
Subject: Re: [EVDL] gas tax (EV transmission lines, not oil pipelines)
The AC and the DC losses can be equal in the best case but if the AC is
degraded then the DC will have less losses than AC. as I said. The
reason
that AC is used is because of two factors: al generators have more loss
than alternators. the commutator has some loss associated. Alternators
have
no commutator associated with the stator where the power is collected.
and
transformers are quite efficient in raising or lowering voltage levels.
However DC must be level shifted via semiconductor switching
components
which are not as efficient as a simple transformer then the DC must be
inverted to be rendered compatible with our load devices to perform our
designated work. The long distance transmission lines must be operated
at
high voltages to keep current levels down and minimise resistive
losses.
with ac that is easy and efficiently done with transformers, and with
DC we
must use inverters and DC/DC voltage reducers which are less efficient
and
more expensive than the AC transformers. Excuse the lecture but I
lectured
on AC/DC basics and Industrial Electricity and worked with it for about
50
years...
*Dennis Lee Miles *
*Director **E.V.T.I. Inc.*
*E-Mail:* *evprofes...@evprofessor.com* <evprofes...@evprofessor.com>
*Phone #* *(863) 944-9913*
Dade City, Florida 33523
USA
On Wed, Jun 25, 2014 at 10:32 PM, Robert Bruninga via EV
<ev@lists.evdl.org>
wrote:
>> "I thought I²R heating was greater for DC.
> NO, if the power factor is perfect, the losses due to current
> squared times circuit resistance, are... the same for AC and DC,
I can see that my original statement was confusing. What I meant was
that
for the same conductor and same I^2R loss, DC can deliver nearly 40%
more
power because the DC line can operate at the PEAK voltage rating of
the
line, whereas the AC line only delivers that same current power at
RMS
voltage, not peak. 40% increase is worth doing for long
point-to-point
transmission (with no taps)
> On Wed, Jun 25, 2014 at 3:11 PM, Robert Bruninga wrote:
> >
> > > > [the main] reason we have AC transmission
> > > > is due the difficulties sending DC over long distances.
> > >
> > > But for very long distances, high voltage DC wins. At very long
> > > distances AC is inefficient due to capacitance (and much
> > > shorter when underground/underwater). AC also has additional
> > Peak vs RMS IsquareR losses.
>
> > On Wed, Jun 25, 2014 at 12:02 PM, Robert Bruninga wrote:
> > > > Somebody has to pay for road repairs.
> > > > Pipelines are a different issue.
> > >
> > > Rather than spending $billons of dollars on a pipeline monument
to
the
> > > past, it is better to make that same investment into electrical
> > > transmission lines for now and the future instead.
> > >
> > > The only thing holding back a near infinite supply of FREE
renewable
> > > energy is the lack of the long haul transmission lines to get
the
solar
> > > and wind energy from where it is abundant (the plains) to where
it is
> > > needed. Pipelines do the same thing for oil but are an ultimate
> > dead-end.
> > >
> > > Anyone want to invest in finding a way to send copper
conductors
> through
> > > old pipelines to convert obsolete pipelines to underground DC
> > transmission
> > > lines?
> > >
> > > Bob, Wb4aPR
>
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