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Old March 17th 08, 07:54 PM posted to rec.crafts.metalworking
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Default New electrical generator

On Mon, 17 Mar 2008 14:40:24 -0500, Bill wrote:

Louis Ohland wrote in
:

Hmm, Toshiba. Sure ain't no laptop....
http://www.springfield.il.us/NewGraphics/Generator2.jpg

snip

That is they euphemistically call a 'luggable' in the biz.

Bill


Springfield, eh? Did Monty order this for his nuclear plant?

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

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Old March 17th 08, 08:16 PM posted to rec.crafts.metalworking
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Default New electrical generator

Phil Kangas wrote:
Yah, this guy claims to have invented a new form of
generator and claims it is not a perpetual motion
device! I'm a skeptic but here is the link so you
can decide for yourself. I'm going to keep my wallet
in my pocket......phil

http://www.nullgrav.com/index.htm


I went to the link and clipped this, "Suppose you could harness the physics of magnetism to allow a generator to continually spin with a net output of free electricity?"

A few days ago I was reading (really scanning) Popular Science ( ? April 2008) and noted the 2015 (?) Volvo is to have individual electric motors at each wheel. It also mentioned permanent magnets in the hub/stator of such motors. It also seems they were to reverse the magnetism as part of the braking process.

They *could* be on to something. -- Don't know. My wallet is in my pocket also! ;-)
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Old March 17th 08, 10:17 PM posted to rec.crafts.metalworking
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Default New electrical generator



Don Foreman wrote:
Horsepuckey! There is no such theoretical limit of efficiency. There
is no way the large turbine-driving generators enclosed in helium are
anywhere near as low as 85% efficient. They'd melt in minutes.

I think most are cooled by hydrogen, not helium. H is a better heat
conductor than He, although that is pretty good, too. The excitation in
a typical power house alternator is something like 1000 A at 100 V
across two strips of copper bar about 50 feet long, total. They are
usually something like 1/4" x 2" bar hammered into a pair of spiral
grooves cut into the solid steel rotor. So, the rotor has bars in it
that dissipate 100 KW anytime the alternator is excited.

Now, these numbers seem extreme util you compare them to the output of
the alternator, which can run to 1 GW, but something around 750 - 850 MW
is typical. Suddenly, that massive exciter dissipation is a tiny .01%
of the rated output!

I don't have a good figure handy for iron and copper losses in the
stator of these machines, but it is definitely no more than a couple %
of full output. Windage would be substantial if they weren't
hydrogen-cooled, as the air gap is an amazing ,002" or so, even though
the rotors are HUGE!

Jon

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Old March 17th 08, 10:19 PM posted to rec.crafts.metalworking
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Default New electrical generator



Robert Swinney wrote:
Don sez:

"However, the underlying premise is either flawed or utter bull****", I vote both.

No, his bull is actually pretty good. Of course, as pure bull, all you
need is a
little engineering or Physics knowledge, and the cracks start to open
pretty wide in his arguments.

Jon

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Old March 17th 08, 10:22 PM posted to rec.crafts.metalworking
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Default New electrical generator



Al Patrick wrote:
Phil Kangas wrote:

Yah, this guy claims to have invented a new form of
generator and claims it is not a perpetual motion
device! I'm a skeptic but here is the link so you
can decide for yourself. I'm going to keep my wallet
in my pocket......phil

http://www.nullgrav.com/index.htm



I went to the link and clipped this, "Suppose you could harness the
physics of magnetism to allow a generator to continually spin with a net
output of free electricity?"

A few days ago I was reading (really scanning) Popular Science ( ? April
2008) and noted the 2015 (?) Volvo is to have individual electric motors
at each wheel. It also mentioned permanent magnets in the hub/stator of
such motors. It also seems they were to reverse the magnetism as part
of the braking process.

They *could* be on to something. -- Don't know. My wallet is in my
pocket also! ;-)


This is typical hybrid tech, and will be out on other makes probably
well before 2015.

Jon



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Old March 17th 08, 10:53 PM posted to rec.crafts.metalworking
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Default New electrical generator


"Jon Elson" wrote in message
...


Don Foreman wrote:
Horsepuckey! There is no such theoretical limit of efficiency. There
is no way the large turbine-driving generators enclosed in helium are
anywhere near as low as 85% efficient. They'd melt in minutes.

I think most are cooled by hydrogen, not helium. H is a better heat
conductor than He, although that is pretty good, too. The excitation in a
typical power house alternator is something like 1000 A at 100 V across
two strips of copper bar about 50 feet long, total. They are usually
something like 1/4" x 2" bar hammered into a pair of spiral grooves cut
into the solid steel rotor. So, the rotor has bars in it that dissipate
100 KW anytime the alternator is excited.

Now, these numbers seem extreme util you compare them to the output of the
alternator, which can run to 1 GW, but something around 750 - 850 MW is
typical. Suddenly, that massive exciter dissipation is a tiny .01%
of the rated output!

I don't have a good figure handy for iron and copper losses in the stator
of these machines, but it is definitely no more than a couple % of full
output. Windage would be substantial if they weren't hydrogen-cooled, as
the air gap is an amazing ,002" or so, even though the rotors are HUGE!


Efficiency of large power-plant generators runs around 98%, shaft input
power to electrical output.

--
Ed Huntress


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Old March 18th 08, 05:25 AM posted to rec.crafts.metalworking
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Default New electrical generator

Ed Huntress wrote:
"Jon Elson" wrote in message
...


Don Foreman wrote:

Horsepuckey! There is no such theoretical limit of efficiency. There
is no way the large turbine-driving generators enclosed in helium are
anywhere near as low as 85% efficient. They'd melt in minutes.


I think most are cooled by hydrogen, not helium. H is a better heat
conductor than He, although that is pretty good, too. The excitation in a
typical power house alternator is something like 1000 A at 100 V across
two strips of copper bar about 50 feet long, total. They are usually
something like 1/4" x 2" bar hammered into a pair of spiral grooves cut
into the solid steel rotor. So, the rotor has bars in it that dissipate
100 KW anytime the alternator is excited.

Now, these numbers seem extreme util you compare them to the output of the
alternator, which can run to 1 GW, but something around 750 - 850 MW is
typical. Suddenly, that massive exciter dissipation is a tiny .01%
of the rated output!

I don't have a good figure handy for iron and copper losses in the stator
of these machines, but it is definitely no more than a couple % of full
output. Windage would be substantial if they weren't hydrogen-cooled, as
the air gap is an amazing ,002" or so, even though the rotors are HUGE!



Efficiency of large power-plant generators runs around 98%, shaft input
power to electrical output.

That might not count the exciter, then. The exciter is
generally a HUGE transformer-rectifier set connected through
slip rings, although some systems use brushless excitation. Our
local utility uses all slip-ring coupled excitation for some
reason, maybe corporate inertia. But, I think all of them use
ono-rotary exciters, however they are coupled.

Jon
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Old March 18th 08, 05:25 AM posted to rec.crafts.metalworking
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Default New electrical generator


"Ed Huntress" wrote: Efficiency of large power-plant generators runs
around 98%, shaft input
power to electrical output.

^^^^^^^^^^^^^^^^^^
Do you have any kind of ballpark figure of the efficiency of the
distributionn grid, from the generator terminals to the average consumer? I
would like to know this, because when people talk about the cleanliness of
electric cars, they frequently forget that there is CO2 coming out the
stacks at the power plant. Steam generation plants run MUCH cleaner than
automotive IC engines, but how much of that advantage do we lose in the
grid?


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Old March 18th 08, 05:33 AM posted to rec.crafts.metalworking
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Default New electrical generator


"Leo Lichtman" wrote in message
...

"Ed Huntress" wrote: Efficiency of large power-plant generators runs
around 98%, shaft input
power to electrical output.

^^^^^^^^^^^^^^^^^^
Do you have any kind of ballpark figure of the efficiency of the
distributionn grid, from the generator terminals to the average consumer?
I would like to know this, because when people talk about the cleanliness
of electric cars, they frequently forget that there is CO2 coming out the
stacks at the power plant. Steam generation plants run MUCH cleaner than
automotive IC engines, but how much of that advantage do we lose in the
grid?


Nope, I don't have it, but I've seen it all other the place on the Web. I'd
have to go looking but you probably can find it yourself. There's quite a
range, depending on where you are in relation to a generating station and
how the network operates, but you probably can find some average figures.

Let me know if you draw a blank. I've been bouncing all over the Web on
energy related issues lately but I think I can come up with it.

--
Ed Huntress


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Old March 18th 08, 05:42 AM posted to rec.crafts.metalworking
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Default New electrical generator

On 2008-03-18, Ed Huntress wrote:

"Leo Lichtman" wrote in message
...

"Ed Huntress" wrote: Efficiency of large power-plant generators runs
around 98%, shaft input
power to electrical output.

^^^^^^^^^^^^^^^^^^
Do you have any kind of ballpark figure of the efficiency of the
distributionn grid, from the generator terminals to the average consumer?
I would like to know this, because when people talk about the cleanliness
of electric cars, they frequently forget that there is CO2 coming out the
stacks at the power plant. Steam generation plants run MUCH cleaner than
automotive IC engines, but how much of that advantage do we lose in the
grid?


Nope, I don't have it, but I've seen it all other the place on the Web. I'd
have to go looking but you probably can find it yourself. There's quite a
range, depending on where you are in relation to a generating station and
how the network operates, but you probably can find some average figures.

Let me know if you draw a blank. I've been bouncing all over the Web on
energy related issues lately but I think I can come up with it.




Wikipedia has a good "power transmission" article.

i


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