Author: Eric GisinDate: 09:41 23-04-08
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""Black Ass Slave? (3) ¼ :)"" <boobooililililil@roadrunner.com>
wrote in message
news:480f2bc6$0$4087$4c368faf@roadrunner.com...
> Bret Cahill wrote:
>> Is there some low frequency radiation or hysterisis loss or what?
>>
> It's not more efficient. That's why Edison's DC power idea failed and
Westinghouse's AC
> prevailed.
Idiot. We had DC here 100 years ago. People near the hydro plant got 130V,
those at the fringes got varying voltage well below 100V depending on load.
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Author: Michael MoroneyDate: 10:26 23-04-08
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Bret Cahill <BretCahill@aol.com> writes:
>Is there some low frequency radiation or hysterisis loss or what?
I won't argue the "10 times" part, but DC power transmission is more
efficient because:
Line inductance and capacitance are unimportant with DC. With AC they
contribute to "imaginary" power, where the system has to transmit power
(with losses) that does no work, because voltage and current are out of
phase.
Line radiation. I don't know how big an effect this is.
DC utilizes a line 100% of the time. An AC insulator has to withstand
the peak AC voltage (1.414 times the RMS value) but most of the time the
instantaneous voltage is lower and thus the instantaneous power is also
lower. It even goes to zero twice per cycle. A DC line will remain at the
peak voltage 100% of the time. Which will fill a kiddie pool faster, a
garden hose left on or a garden hose repeatedly turned off and on?
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Author: Puppet_SockDate: 10:53 23-04-08
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On Apr 22, 3:13=A0pm, Bret Cahill <BretCah...@aol.com> wrote:
> Is there some low frequency radiation or hysterisis loss or what?
Well, as others have ragged on about, the quoted change
in efficiency isn't very meaningful. The efficiency of a transmission
line depends on many things. And efficiency is received energy
divided by transmitted energy.
The situation where DC transmission is better is where the
transmission line is long compared to a 1/4 wavelength of
the AC transmission frequency. The typical transmission is
60 cps. So 3E8 m/s divided by 60/s, then divided by 4, is
1,250 km. So when you get transmission distances in
that range, radiative loss starts to be significant, and it
gets tough to match the impedance of the line to the load.
Basically what you get is a very large dipole antenna.
DC will remove that effect.
It's not a free ride though. DC transmission lines
require that you have high voltage DC to transmit. And most
generating stations do not produce DC. So you need to
get from AC to high voltage DC, and back to AC at the
receiving end. This is doable, but it
does have losses. It has only been relatively recently that
this process has been improved to the point of being useful,
say the last 20 years or so. This is because large scale
grids have been finding it useful to transmit power over
distances of that scale. So people found it worthwhile
to start doing the engineering to make the improvements.
Heh heh. A few years ago I was working at the head office
of Ontario Power Generation, writing software for their
power trading guys. The grid in Ontario is operated by
an agency called the IMO. They had a rule that if you
offered to sell power, but the grid was congested so that
you couldn't get it to the buyer, you got paid compensation.
A utility in Wisconsin noticed they could bid to sell power
in New York state, transmitting it through Ontario. And
they noticed that the connections were not large enough
to carry the amount of power they were offering, if there
was even a very small amount of power already on them.
Now the compesation was based on the difference between
what they offered to sell it for and what the buyer offered to
buy it for. So the guys in Wisconsin were essentially offering
it for free to assure they'd win the bid. But the buyers had
to pay for it at the market rate in NY. So basically, the guys
in Wisconsin were getting paid pretty much the full price.
They were getting paid *not* to sell electricity to NY
for many hours a day. And in amounts of 100's of MW.
The IMO very quickly had an emergency meeting and
changed the rules to disallow this.
Anyway, long distance transmission is sometimes done
on DC lines to reduce radiative loss.
Socks
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Author: Jim PenninoDate: 11:45 23-04-08
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In sci.physics "Blattus Slafaly ? (3) ? :)"
<boobooililililil@roadrunner.com> wrote:
> Bret Cahill wrote:
> > Is there some low frequency radiation or hysterisis loss or what?
> >
> >
> > Bret Cahill
> >
> >
> >
> >
> It's not more efficient. That's why Edison's DC power idea failed and
> Westinghouse's AC prevailed.
Apples and oranges.
Power companies are out to make money.
The economic cost of losses for a DC system can be significantly less
than that of an AC system over long distances.
For short distances, the cost of the losses are generally less than
the cost of the conversion equipment, so AC is usually used.
There are many reasons why a DC system would be prefered depending
on the situation.
Start here:
http://en.wikipedia.org/wiki/Hvdc
--
Jim Pennino
Remove .spam.sux to reply.
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Author: Bret CahillDate: 12:04 23-04-08
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> The typical transmission is
> 60 cps. So 3E8 m/s divided by 60/s, then divided by 4, is
> 1,250 km. So when you get transmission distances in
> that range, radiative loss starts to be significant, and it
> gets tough to match the impedance of the line to the load.
> Basically what you get is a very large dipole antenna.
If we can't get sustainable maybe we can signal ETs for help.
Bret Cahill
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Author: BenjDate: 12:20 23-04-08
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On Apr 22, 8:11 pm, tadchem <tadc...@comcast.net> wrote:
> On Apr 22, 6:05 pm, Benj <bjac...@iwaynet.net> wrote:
> > > The OP's question is an absurd troll.
>
> > > Like you.
>
> > > ...... Phil
>
> > Are modern "scientists" really this dense? Ten times efficient
isn't
> > 920%! What you must have just graduated from a "modern" high
school?
> > Dig. If standard transmission is 92% efficient, then that means there
> > is 8% of the energy lost.
>
> That's 8% INefficiency
Yes, AND 92% efficiency at the same time! Duh!
> > TWICE as efficient would only have 4% of the
> > energy lost or would be 96%.
>
> Your 4% would be HALF as INefficient; not at all the same thing.
AND also twice as efficient! eg. 96% efficient. Moron.
> 10 x 92% is still 920%.
Isn't it great when a so-called "scientist" can simply quote
mathematical equations as if they were making sense and pretend to win
arguments by doing so? [I know it's common practice now] That is
"complete bollocks" to use Phil's colorful scientific argument! So
just what is 920% "efficiency"? I guess it's a transmission line where
nine times as much power comes out as you put in! That would be a
WONDERFUL way for Europeans to transmit power from the Sahara to
Europe! When mathematics doesn't agree with reality it is MATHEMATICS
that is thrown out!
You know, I need to introduce both you and Phil to another troll who
speaks latin and loves to correct people who speak "muttish".
Her Name is Autyme! [apparently nurse Ratched isn't letting her on
the ward computer these days]
> > The interested student can take it from
> > there...
Sorry Tom, D+ on this one!
> > Since 10X would be more than 99% efficient I am somewhat skeptical
> > that even modern converters can produce so little loss.
>
> Tom Davidson
> Richmond, VA
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Author: Richard TobinDate: 12:33 23-04-08
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In article <068b228f-f5c8-44af-8fb2-a633bd413666@24g2000hsh.googlegroups.com>,
Benj <bjacoby@iwaynet.net> wrote:
>Are modern "scientists" really this dense? Ten times efficient isn't
>920%! What you must have just graduated from a "modern" high school?
>Dig. If standard transmission is 92% efficient, then that means there
>is 8% of the energy lost. TWICE as efficient would only have 4% of the
>energy lost or would be 96%.
Your terminology seems pointlessly confusing. Presumably you think
a 100% efficient system is 20 times as efficient as another 100%
system.
The simple answer is that if something is 92% efficient, you can't
make it 10 times more efficient.
-- Richard
--
:wq
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Author: Bret CahillDate: 16:06 23-04-08
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> you came up
> with.
Never end sentences with prepositions.
Bret Cahill
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Author: Paul E. SchoenDate: 16:11 23-04-08
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Author: Bret CahillDate: 18:02 23-04-08
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> >> you came up
> >> with.
>
> > Never end sentences with prepositions.
>
> But it sounds funny to say, "up with which you came."
Then rewrite the entire sentence:
"Bret doesn't know jack about how to express transmission line
efficiency."
Bret Cahill
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Author: Phil AllisonDate: 19:32 23-04-08
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"Benj"
( snip nauseating verbal diarrhoea)
** Fuck OFF - you asinine, illiterate cretin !!!
.... Phil
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Author: Phil AllisonDate: 19:34 23-04-08
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"Bret Cahill = TROLL "
> Never end sentences with prepositions.
** So it is a rote thinker -
as well as a complete fuckwit.
..... Phil
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Author: tadchemDate: 20:02 23-04-08
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On Apr 23, 12:20 pm, Benj <bjac...@iwaynet.net> wrote:
> On Apr 22, 8:11 pm, tadchem <tadc...@comcast.net> wrote:
>
<snip>
>
> > That's 8% INefficiency
>
> Yes, AND 92% efficiency at the same time! Duh!
No argument there.
<snip>
>
> > Your 4% would be HALF as INefficient; not at all the same thing.
>
> AND also twice as efficient! eg. 96% efficient. Moron.
You obviously have a flawed understanding of the concept of
'efficiency.' It is *precisely* defined as a ratio - a mathematical
'equation' (whether you approve or not):
Note the various definitions here, used for specific cases.
http://en.wikipedia.org/wiki/Thermodynamic_efficiency
In all cases, the efficiency is the *ratio* of usable energy output to
total energy input. Since energy output cannot exceed input,
efficiency can never be greater than 1.
To multiplying the efficiency by 2x, you need to do something such as
double the output while maintaining a constant input. 96% efficiency
is therefore twice as efficient as 48% efficiency.
More apropos to the OP is the following article.
http://en.wikipedia.org/wiki/Electric_power_transmission#Bulk_power_transmission
"Transmission efficiency is improved by increasing the voltage using a
step-up transformer, which reduces the current in the conductors,
while keeping the power transmitted nearly equal to the power input.
The reduced current flowing through the conductor reduces the losses
in the conductor and since, according to Joule's Law, the losses are
proportional to the square of the current, halving the current makes
the transmission loss one quarter the original value."
While AC has slight radiative losses, DC has strong resistive losses.
In both, higher voltage means lower current is necessary to transmit a
given amount of power. AC can be easily (and efficiently) increased
in voltages through step-up transformers. High voltage DC is harder
and less efficient to produce and to use.
> Isn't it great when a so-called "scientist" can simply quote
> mathematical equations as if they were making sense
...and they do make sense, especially when you consider that these
equations are definitions and not open to debate.
> and pretend to win
> arguments by doing so?
I pretend nothing. Why do you pretend to understand when your
argument violates simple arithmetic?
2 x 92% is 184%, and 184% efficiency is impossible as efficiency is
defined.
Can you show me *HOW* 2 x 92% = 96%? I don't think so.
By my math, 96% = 1.04347826 * 92%, roughly.
> [I know it's common practice now] That is
> "complete bollocks" to use Phil's colorful scientific argument! So
> just what is 920% "efficiency"?
An egregious error, just as wrong as claiming that 2 x 92% = 96%
Tom Davidson
Richmond, VA
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Author: tadchemDate: 20:09 23-04-08
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On Apr 23, 4:06 pm, Bret Cahill <BretCah...@aol.com> wrote:
> > you came up
> > with.
>
> Never end sentences with prepositions.
>
> Bret Cahill
An infamous feud was carried on between Winston Churchill and Lady
Astor.
On one occasion she accused the PM of ending a sentence with a
preposition.
Churchill replied, IIRC, "Madam, that is an accusation up with which I
shall not put."
Tom Davidson
Richmond, VA
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Author: Phil AllisonDate: 21:30 23-04-08
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"Puppet_Sock"
The situation where DC transmission is better is where the
transmission line is long compared to a 1/4 wavelength of
the AC transmission frequency. The typical transmission is
60 cps. So 3E8 m/s divided by 60/s, then divided by 4, is
1,250 km. So when you get transmission distances in
that range, radiative loss starts to be significant, and it
gets tough to match the impedance of the line to the load.
Basically what you get is a very large dipole antenna.
Anyway, long distance transmission is sometimes done
on DC lines to reduce radiative loss.
** I think this is entirely false.
There is no comparison with a 60 Hz dipole antenna.
AC power transmission is done with 3-phases ( spaced by exactly 120
degrees ) running a few metres apart, all in exact parallel across the
country - so the net 60Hz eclectic field at a distance always cancels to
ZERO !!.
Ergo, there simply is no "radiation loss" .
The real losses encountered are due to resistive heating, voltage drop and
phase angle changes on very long lines.
http://en.wikipedia.org/wiki/Electric_power_transmission#Limitations
..... Phil
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On Wed, 23 Apr 2008 13:06:05 -0700 (PDT), Bret Cahill
<BretCahill@aol.com> wrote:
>> you came up
>> with.
>
>Never end sentences with prepositions.
Why?
jack
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Author: Phil AllisonDate: 01:49 24-04-08
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<spamfree@spam.heaven>
Bret Cahill = TROLL
>>> you came up with.
>>
>>Never end sentences with prepositions.
>
>
> Why?
** Cos it is a preposterous thing to do.....
..... Phil
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Author: BenjDate: 02:21 24-04-08
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On Apr 23, 7:32 pm, "Phil Allison" <philalli...@tpg.com.au> wrote:
> "Benj"
>
> ( snip nauseating verbal diarrhoea)
>
> ** Fuck OFF - you asinine, illiterate cretin !!!
>
> .... Phil
GREAT NEWS PHIL!!!!
Google Groups now can be rigged with a killfile!
Bye Bye, fuckwit!
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Author: Y.PoratDate: 02:37 24-04-08
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On Apr 23, 1:17=A0am, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Tue, 22 Apr 2008 12:13:06 -0700 (PDT), Bret Cahill
>
> <BretCah...@aol.com> wrote:
> >Is there some low frequency radiation or hysterisis loss or what?
>
> >Bret Cahill
>
> If you mean long-distance transmission lines, DC can be run at higher
> average voltages (less corona losses, relatively) and has no skin loss
> or inductive coupling to the world. I don't know about 10:1.
>
> DC systems do need inverters and rectifiers on the ends, which have
> losses.
>
> John
----------------
i dont know what you mean by inverters
AFAIK
DC cannot be transform to very high volages-
OTHOA
AC can be transformed to huge voltages by trasformers
yet transformers can work only on AC
and hight voltage AC is much more efficient than
any low voltage current
do i remember correctly ??
ATB
Y.Porat
---------------------------
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Author: BenjDate: 02:44 24-04-08
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On Apr 23, 8:02 pm, tadchem <tadc...@comcast.net> wrote:
> > Isn't it great when a so-called "scientist" can simply quote
> > mathematical equations as if they were making sense
>
> ...and they do make sense, especially when you consider that these
> equations are definitions and not open to debate.
Since when are equations in science and engineering "not open to
debate"? It is only in MATHEMATICS that they are unquestioned
(assuming they were done "correctly" which means according to the
arbitrary rules the original mathematician who defined the given
system invented.) In science and engineering (contrary to popular
belief) mathematical models are determined to be "correct" by their
agreement with reality. mathematical definitions play NO role!
> > and pretend to win
> > arguments by doing so?
>
> I pretend nothing. Why do you pretend to understand when your
> argument violates simple arithmetic?
Because simple arithmetic leads to an absurd answer and therefore
simply does not apply!
> 2 x 92% is 184%, and 184% efficiency is impossible as efficiency is
> defined.
Correct. Absurd answer so the calculation is simply untenable and
thrown out without regrets.
> Can you show me *HOW* 2 x 92% = 96%? I don't think so.
By looking at the data. It's clear that if one system has half as
much loss as another the one with the greater loss is twice as
inefficient. Hence it logically follows from the data that one is
twice as efficient as the other. If you want to play English word
games have at it, but language doesn't have to make sense either,
ESPECIALLY "muttish" English! If you wish to make up equations that
have no basis in reality and then claim that somehow it shows you are
"correct" because the laws of arithmetic are being followed, you can
say that, but you make no sense in a practical world. Say, how is
life up there in the Ivory Tower?
So the REAL question is what is going on in the system? Trying to
press mathematical dogma or the rules of English grammar upon any
situation in no way impresses the power transmission systems. They
don't listen to either mathematics OR English. If what is going on is
understood and described, that is sufficient for those people who deal
with these things. Goofy arguments by you don't make you look any
smarter.
If you want to look smart then tell us what the best efficiency of
AC<>DC HV converters are these days... (only values under 100% will be
considered valid)
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