Who Invented Three-Phase?
HardySpicer
http://www.edisontechcenter.org/OskarVonMiller.html
Nikola Tesla
http://en.wikipedia.org/wiki/Nikola_Tesla
and
Galileo Ferraris
http://en.wikipedia.org/wiki/Galileo_Ferraris and
John Hopkinson
http://en.wikipedia.org/wiki/John_Hopkinson
Hardy
m II
Hash: SHA1
Edison cheated Tesla out of billions of dollars. Looks like the cover up
is still in progress. Westinghouse screwed him too.
mike
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Benj
> Seems to be some confusion, I have Oskar Von Miller
> http://www.edisontechcenter.org/OskarVonMiller.html
Close but no cigar. Tesla beat him by at least a year, probably more.
> Nikola Tesla
> http://en.wikipedia.org/wiki/Nikola_Tesla
Most likely the winner. Certainly invented the rotating field concept
which is essential to his invention of the induction motor.
> and
> Galileo Ferraris
> http://en.wikipedia.org/wiki/Galileo_Ferraris and
This guy is probably a "parallel" inventor. Time frame is about the
same as Tesla though his patent was issued about the time of the
Ferraris paper which could give Tesla a slight edge (takes time from
idea to patent), but without an exact time-frame for each man, it's
hard to say for sure. But Tesla does have the patent and that was
never challenged.
> John Hopkinson
> http://en.wikipedia.org/wiki/John_Hopkinson
Nope. Only invented three phase power transmission. Though had
priority for that (1882 patent) He did not invent induction motors or
the rotating field.
Although for any important invention, there are always lots of "after
the fact" persons discovered later for whom it is often claimed the
invention (or their "friends" claim it for them). This is very
common.
A guy I used to work with had this "seeds" theory about it. His
"theory" was that when it was time for a new invention in the world,
the "powers that be" would sort of drop "seeds" for the new idea from
heaven. They would fall all over the earth. Some inventors would pick
them up and run with them. Some would sort of give them a look and
nothing more and others would ignore them or not notice them at all.
Yes, it's kind of a "joke" theory, but on the other hand it does fit
the data of the way great inventions commonly happen. It is VERY
common for 'great" inventions to appear simultaneously in several
places around the world at the same time!
And then one must add to the the politically motivated erasure of
Tesla's achievements from technical history. Started by J.P. Morgan
who basically "milked" Tesla for anything profitable ("Nobody milks my
cow for free!") and continued pretty much to this day because of
certain interests of Tesla that the power-elite would just as soon the
general public not consider as real science. Even now, if one mentions
Tesla there are the "debunkers" on the internet who descend to call
him "insane". The fact that this "nutjob" held about 300 patents that
cover most of the major devices that defined the 20th century from the
fluorescent lamp to the car speedometer is swept under the rug.
HardySpicer
I only wanted the invention of 3 phase, not the rotating magnetic
field or the induction motor.
Maybe Hopkinson then.
ji...@specsol.spam.sux.com
Lots of people worked on polyphase power systems, but it was Tesla that
patented three phase.
--
Jim Pennino
Remove .spam.sux to reply.
WangoTango
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 06/20/2011 08:56 PM, HardySpicer wrote:
> > Seems to be some confusion, I have Oskar Von Miller
> >
> > http://www.edisontechcenter.org/OskarVonMiller.html
> >
> > Nikola Tesla
> >
> > http://en.wikipedia.org/wiki/Nikola_Tesla
> >
> > and
> >
> > Galileo Ferraris
> >
> > http://en.wikipedia.org/wiki/Galileo_Ferraris and
> >
> > John Hopkinson
> >
> > http://en.wikipedia.org/wiki/John_Hopkinson
>
>
> Edison cheated Tesla out of billions of dollars. Looks like the cover up
> is still in progress. Westinghouse screwed him too.
Edison was a hack that stole much more than he ever invented.
Tesla was just another brilliant guy in Edison's employ that did all the
work, came up with all the innovations, and Edison took all the credit
and money. A true poster boy for Wall Street, but no great inventor.
Michael Moroney
systems was 90 degree 2 phase power. By this I mean two wires to the
load carried AC at 0 degrees and two others (separate circuit) carried
AC at 90 degrees to the first pair. This produced a rotating field
in a 2 phase motor and constant power (since sin**2(x) + cos**2(x) = 1).
You needed 4 wires.
You could connect two of the wires (one from each phase), call it
a neutral and get away with three wires, but the neutral carries
quite a bit of current. Three phase is better at carrying more power
with the same copper in three wires, which is why you don't see two
phase power any more, except in some specialty motor control
circuits.
There was another early power system that was a cross between two
phase and the single phase Edison system still used in the US. Take
the existing Edison system and add a supply at 90 degrees, connected to
the neutral center tap. Lights were connected as usual to the Edison
system and motors as well, but the extra phase was connected to a starting
winding on the motors. One thing that was interesting about this was,
as long as you had at least one motor running, it would generate the
extra phase and could start other motors even if the extra phase was
not being supplied by the utility. Some people use a similar trick
to run small 3 phase motors off the US domestic single phase supply,
by running a (manually started) idler motor that generates three phases
for other motors connected to it.
Tim Wescott
Usually the idler motor is capacitor start. Why manually start it when
you can get start caps surplus? Search on "rotary phase converter".
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html
Tim Wescott
Some of these things just grow out of the spirit of the times, getting
invented multiple times by multiple people in multiple places.
Three-phase power is certainly one of those technologies that would
easily have more than one daddy.
George Herold
Isn't the 'purpose' of three phase to run induction motors?
George H.
> - Show quoted text -
HardySpicer
No, it's a method of distribution that is more efficient than single
phase for the same amount of copper.
Three phase supplies our homes - except we use only one of the phases
of course. Small induction motor can run on single phase
with a capacitor start to simulate a second phase.
Hardy
Michael Moroney
>Usually the idler motor is capacitor start. Why manually start it when
>you can get start caps surplus? Search on "rotary phase converter".
It certainly makes sense to start the idler capacitively. The
setup I saw was relatively simple compared to some of the setups
that turn up when searching for "rotary phase converter".
George Herold
>
> - Show quoted text -
OK, I always associate three phase with running induction motors,
lathes and mills in a machine shop for instance. I don't know about
power transmission.
George H.
Rich Grise
less filtering than single-phase.
Cheers!
Rich
VWWall
output tubes, use transformers to convert the three phase supply to six
phase before rectifying it. This reduces the filtering required still more.
--
Virg Wall, P.E.
m II
Hash: SHA1
On 06/21/2011 01:15 PM, HardySpicer wrote:
> No, it's a method of distribution that is more efficient than single
> phase for the same amount of copper.
> Three phase supplies our homes - except we use only one of the phases
> of course. Small induction motor can run on single phase
> with a capacitor start to simulate a second phase.
Distribution was a secondary benefit of 3 phase. The initial idea was
motor rotation and start-up without commutation or extra windings. The
ease of motor reversal was also in that initial idea. The rotating
magnetic field was the MAIN attraction.
The root 3 factor in the volume of power delivery came in later. It
could be argued that 3 phase distribution happened only because the 3
phase motors were appealing to industry and most likely caused the end
of the somewhat dangerous belt and shaft method power distribution in
factories.
mike
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upsid...@downunder.com
<gyans...@gmail.com> wrote:
>> Isn't the 'purpose' of three phase to run induction motors?
>>
>> George H.
>>
>> > - Show quoted text -
>
>No, it's a method of distribution that is more efficient than single
>phase for the same amount of copper.
Definitely.
>Three phase supplies our homes - except we use only one of the phases
>of course. Small induction motor can run on single phase
>with a capacitor start to simulate a second phase.
In some European countries, the maximum allowed single phase motors
are about 1 kW.
The smallest induction motor that I have at home in the central
heating system circulation water pump with perhaps 100 W power (my
guess based on the motor size) protected by 3 x 2 A fuses.
Starting capacitors are used with single phase low power units.
Universal AC/DC motors are used with hand tools etc.
m II
Hash: SHA1
You're thinking of diodes, not transformers. Once a three phase supply
is rectified, you get all the peaks (six of them) on the same side of
the zero line in a 2Pi period. It takes six diodes to do that, two per
phase.
Think car alternator.
Transformers will not give you extra phases. You can get multiple taps
from a secondary, but those aren't extra phases.
The valleys between the rectified peaks are really small, with none of
them reaching anywhere near zero volts. That's why the filtering is so
much easier. Power supply filtering cuts off the tops of the peaks and
uses it as landfill in the valleys.
mike
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Don Lancaster
More to start them than to run them.
--
Many thanks,
Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: d...@tinaja.com
Please visit my GURU's LAIR web site at http://www.tinaja.com
HardySpicer
Well don't think that the whole world of power revolves around the
induction motor. It is more efficient to use 3 phase.
VWWall
any event the six diodes are fed by six voltages sixty degrees apart.
Actually, given two orthogonal phases, it is possible to generate many
phase systems. The most common is the Scott-T used to create two phase
power from three phase. This was originally used to drive two phase
motors when three phase power became common. It's main use today is in
instrumentation to convert "synchro" signals to "resolver" signals.
--
Virg Wall
Don Lancaster
> Transformers will not give you extra phases. You can get multiple taps
> from a secondary, but those aren't extra phases.
>
Uh, Mr Scott of Scott Tee fame begs to differ with you.
, http://en.wikipedia.org/wiki/Scott-T_transformer >
m II
Hash: SHA1
On 06/21/2011 05:57 PM, Don Lancaster wrote:
>
>> Transformers will not give you extra phases. You can get multiple taps
>> from a secondary, but those aren't extra phases.
>>
>
> Uh, Mr Scott of Scott Tee fame begs to differ with you.
>
> , http://en.wikipedia.org/wiki/Scott-T_transformer >
>
>
Well, there's that...but let's see it give us six phase from three...
One thing settled is the earlier posting in this thread about three
phase being an answer to distribution needs. This quote from that page
shows the motor needs came first:
=========================
The Scott three-phase transformer was invented by a Westinghouse
engineer, C. F. Scott, in the late 1890's to bypass Edison's more
expensive rotary-converter and thereby permit two-phase generator plants
to drive Tesla's three-phase motors.[1]
=========================
mike
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m II
Hash: SHA1
On 06/21/2011 05:38 PM, VWWall wrote:
> You can think of it as six-phase or as three-phase center-tapped. In
> any event the six diodes are fed by six voltages sixty degrees apart.
The way I see it, it's three lines feeding three diodes. Then, the
return lines each have a diode in them. The slight ripples on the dc
side have a sixty degree peak spacing.
The six peaks result not from six phases, but from the inverted halves
of the rectified three phases. There are no phases at this point anyway,
it's a rectified, slightly pulsating DC waveform.
http://sub.allaboutcircuits.com/images/03269.png
mike
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Spehro Pefhany
<d...@tinaja.com> wrote:
>
>> Transformers will not give you extra phases. You can get multiple taps
>> from a secondary, but those aren't extra phases.
>>
>
>Uh, Mr Scott of Scott Tee fame begs to differ with you.
>
>, http://en.wikipedia.org/wiki/Scott-T_transformer >
You can get extra phases, provided only that you have more than one to
start with.
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
sp...@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
Paul Hovnanian P.E.
[snip]
>
>
> You're thinking of diodes, not transformers. Once a three phase supply
> is rectified, you get all the peaks (six of them) on the same side of
> the zero line in a 2Pi period. It takes six diodes to do that, two per
> phase.
>
> Think car alternator.
>
> Transformers will not give you extra phases. You can get multiple taps
> from a secondary, but those aren't extra phases.
They can give you a second set of three phases, shifted from the input three
phase set by 30 degrees (or multiples thereof). This is accomplished with a
wye-delta transformer configuration.
A standard three phase input to a full wave rectifier gives you six pulses
per cycle. Add one wye-delta transformer and you get a twelve pulse
rectifier. Add a seconf wye-delta (connected to shift 30 degrees the other
way) and you get 18 pulses per cycle.
Each three phase group has 6 rectifiers (same as the number of pulses).
> The valleys between the rectified peaks are really small, with none of
> them reaching anywhere near zero volts. That's why the filtering is so
> much easier. Power supply filtering cuts off the tops of the peaks and
> uses it as landfill in the valleys.
More pulses per cycle, smaller valleys to fill. Less caps needed.
--
Paul Hovnanian mailto:Pa...@Hovnanian.com
------------------------------------------------------------------
Trust the computer industry to shorten the term "Year 2000" to Y2K.
It was this kind of thinking that got us in trouble in the first place.
-- Adrian Tyvand
m II
Hash: SHA1
On 06/21/2011 06:51 PM, Spehro Pefhany wrote:
> On Tue, 21 Jun 2011 16:57:42 -0700, the renowned Don Lancaster
> <d...@tinaja.com> wrote:
>
>>
>>> Transformers will not give you extra phases. You can get multiple taps
>>> from a secondary, but those aren't extra phases.
>>>
>>
>> Uh, Mr Scott of Scott Tee fame begs to differ with you.
>>
>> , http://en.wikipedia.org/wiki/Scott-T_transformer >
>
> You can get extra phases, provided only that you have more than one to
> start with.
The trig gets too weird in anything but the most balanced circuits. I
can see the generated phases working acceptably in a fixed, completely
balanced load.
There are probably a lot easier and cheaper ways to produce multi-phases
than to wire transformers in arcane and most likely demonic configurations.
I'm trying to think what would need more than three phases anyway.
Perhaps mutant stepper motors driving electric cars? Electroplating
rectifiers?
How would you reverse a six phase AC motor easily? The
simplicity/elegance of three phase disappears.
mike
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Benj
> Edison was a hack that stole much more than he ever invented.
> Tesla was just another brilliant guy in Edison's employ that did all the
> work, came up with all the innovations, and Edison took all the credit
> and money. A true poster boy for Wall Street, but no great inventor.
Actually Tesla only worked for Edison for a short time when he arrived
in this country. Edison promised him money to fix a certain electrical
problem and after Tesla fixed it, Edison told him he was joking!
Tesla took off never to return.
Yes, it's true Edison was just an experimenter who didn't understand
the theory and engineering the way Tesla did. His inventions were,
however, high impact if not high tech! Sure ideas like the light bulb,
the phonograph and movies were mostly mechanical experimentation and
trial and error, but there is no denying the HUGE impact these few
devices had on 20th century life!
But oddly enough it was Edison's tendency to to hire bright people and
take credit for their work that was his greatest invention and the one
he almost never given credit for! I'm talking about the modern
industrial R&D lab. Today virtually all industrial research labs are
set up on the Edison model! The "Tesla" model of the brilliant loner
inventor has all but vanished (with a couple of notable exceptions
such as Steinmetz at GE and some others)
George Herold
Sure, but I bet there's a lot more three phase motors than 3 phase DC
supplies in the world.
I wonder what percentage of electrical power goes to spinning motors,
versus other stuff, (lighting, heating, entertainment).
George H.
m II
Hash: SHA1
On 06/21/2011 06:56 PM, Paul Hovnanian P.E. wrote:
> m II wrote:
>
> [snip]
>>
>>
>> You're thinking of diodes, not transformers. Once a three phase supply
>> is rectified, you get all the peaks (six of them) on the same side of
>> the zero line in a 2Pi period. It takes six diodes to do that, two per
>> phase.
>>
>> Think car alternator.
>>
>> Transformers will not give you extra phases. You can get multiple taps
>> from a secondary, but those aren't extra phases.
>
> They can give you a second set of three phases, shifted from the input three
> phase set by 30 degrees (or multiples thereof). This is accomplished with a
> wye-delta transformer configuration.
>
> A standard three phase input to a full wave rectifier gives you six pulses
> per cycle. Add one wye-delta transformer and you get a twelve pulse
> rectifier. Add a seconf wye-delta (connected to shift 30 degrees the other
> way) and you get 18 pulses per cycle.
>
> Each three phase group has 6 rectifiers (same as the number of pulses).
>
>> The valleys between the rectified peaks are really small, with none of
>> them reaching anywhere near zero volts. That's why the filtering is so
>> much easier. Power supply filtering cuts off the tops of the peaks and
>> uses it as landfill in the valleys.
>
> More pulses per cycle, smaller valleys to fill. Less caps needed.
>
I never even thought of wye-delta conversion and then adding it to the
rectified output. Ingenious, but isn't that cheating? Kinda like
starting a second alternator 30 electrical degrees later than the first?
You'd be running two isolated systems that join up only after rectification.
mike
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brent
The only thing I remember from my power class was that 3 phase gave
constant torque, so I always assumed this was what you wanted on big
machines
P E Schoen
news:d4e30129-107e-4467...@y13g2000yqy.googlegroups.com...
> The only thing I remember from my power class was that 3 phase
> gave constant torque, so I always assumed this was what you
> wanted on big machines
If you add the squares of the sines of the three phase angles (at 120
degrees), for any angular rotation, it will be always 1.5. This means that
the total power will be constant. Torque is proportional to Power/Speed.
Speed is generally proportional to voltage, and torque is proportional to
current. So three phase will provide constant torque.
Paul
David Lesher
>OK, I always associate three phase with running induction motors,
>lathes and mills in a machine shop for instance. I don't know about
>power transmission.
The sum of all three phases is always 1.0; i.e. the power does not
vary over the length of a cycle. This makes 3ph good to rectify;
far less filtering needed for DC.
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
upsid...@downunder.com
<pa...@hovnanian.com> wrote:
>m II wrote:
>
>[snip]
>>
>>
>> You're thinking of diodes, not transformers. Once a three phase supply
>> is rectified, you get all the peaks (six of them) on the same side of
>> the zero line in a 2Pi period. It takes six diodes to do that, two per
>> phase.
>>
>> Think car alternator.
>>
>> Transformers will not give you extra phases. You can get multiple taps
>> from a secondary, but those aren't extra phases.
>
>They can give you a second set of three phases, shifted from the input three
>phase set by 30 degrees (or multiples thereof). This is accomplished with a
>wye-delta transformer configuration.
>
>A standard three phase input to a full wave rectifier gives you six pulses
>per cycle. Add one wye-delta transformer and you get a twelve pulse
>rectifier. Add a seconf wye-delta (connected to shift 30 degrees the other
>way) and you get 18 pulses per cycle.
>
>Each three phase group has 6 rectifiers (same as the number of pulses).
On a normal three core three phase transformer, the zigzag arrangement
can generate the number of phases.
The secondary winding for a "new" phase will start on one core and
continue on a different core (phase), thus the induced voltages are
added in vector form. By varying the amount of turns on each of the
cores, all the required phase shifts can be generated on a single
transformer.
The simple 6-pulse rectifier will have quite ugly current waveforms,
causing harm in the feeding distribution systems. The 12- and
especially 18-pulse rectifiers are much more gentle to the feeding
network, by drawing nearly sinusoid current from the network.
Adrian Tuddenham
> m II wrote:
>
> [snip]
> >
> >
> > You're thinking of diodes, not transformers. Once a three phase supply
> > is rectified, you get all the peaks (six of them) on the same side of
> > the zero line in a 2Pi period. It takes six diodes to do that, two per
> > phase.
> >
> > Think car alternator.
> >
> > Transformers will not give you extra phases. You can get multiple taps
> > from a secondary, but those aren't extra phases.
>
> They can give you a second set of three phases, shifted from the input three
> phase set by 30 degrees (or multiples thereof). This is accomplished with a
> wye-delta transformer configuration.
>
> A standard three phase input to a full wave rectifier gives you six pulses
> per cycle. Add one wye-delta transformer and you get a twelve pulse
> rectifier. Add a seconf wye-delta (connected to shift 30 degrees the other
> way) and you get 18 pulses per cycle.
>
> Each three phase group has 6 rectifiers (same as the number of pulses).
>
> > The valleys between the rectified peaks are really small, with none of
> > them reaching anywhere near zero volts. That's why the filtering is so
> > much easier. Power supply filtering cuts off the tops of the peaks and
> > uses it as landfill in the valleys.
>
> More pulses per cycle, smaller valleys to fill. Less caps needed.
A lot more iron in the transformers, though.
--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
Adrian Tuddenham
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 06/21/2011 06:51 PM, Spehro Pefhany wrote:
> > On Tue, 21 Jun 2011 16:57:42 -0700, the renowned Don Lancaster
> > <d...@tinaja.com> wrote:
> >
> >>
> >>> Transformers will not give you extra phases. You can get multiple taps
> >>> from a secondary, but those aren't extra phases.
[...]
> How would you reverse a six phase AC motor easily? The
> simplicity/elegance of three phase disappears.
If your 'six-phase' is coming from tha three-phase transformer, swap two
phases on the transformer primary.
jmfbahciv
> "brent" wrote in message
> news:d4e30129-107e-4467...@y13g2000yqy.googlegroups.com...
>
>> The only thing I remember from my power class was that 3 phase
>> gave constant torque, so I always assumed this was what you
>> wanted on big machines
>
> If you add the squares of the sines of the three phase angles (at 120
> degrees), for any angular rotation, it will be always 1.5. This means that
> the total power will be constant.
That was very important in computer mainframe days.
>Torque is proportional to Power/Speed.
> Speed is generally proportional to voltage, and torque is proportional to
> current. So three phase will provide constant torque.
>
> Paul
>
/BAH
Glen Walpert
> George Herold <ghe...@teachspin.com> writes:
>
>
>>OK, I always associate three phase with running induction motors,
>>lathes and mills in a machine shop for instance. I don't know about
>>power transmission.
>
> The sum of all three phases is always 1.0; i.e. the power does not vary
> over the length of a cycle. This makes 3ph good to rectify; far less
> filtering needed for DC.
The constant power characteristic of 3-phase means you can make an
isolated unity power factor SMPS with no bulk storage capacitor, with 98%
efficiency reported by the inventor of this configuration, Dr. Slobodan
Cuk of TESLAco (Oct 2010 Power Electronics Technology).
Bill Beaty
> On 06/20/2011 07:56 PM, HardySpicer wrote:
>
>
>
> > Seems to be some confusion, I have Oskar Von Miller
>
> >http://www.edisontechcenter.org/OskarVonMiller.html
>
>
> >http://en.wikipedia.org/wiki/Nikola_Tesla
>
> > and
>
> > Galileo Ferraris
>
> >http://en.wikipedia.org/wiki/Galileo_Ferraris and
>
> > John Hopkinson
>
> >http://en.wikipedia.org/wiki/John_Hopkinson
>
> Some of these things just grow out of the spirit of the times, getting
> invented multiple times by multiple people in multiple places.
>
> Three-phase power is certainly one of those technologies that would
> easily have more than one daddy.
Nope, because the whole point of polyphase was to power Westinghouse
corp polyphase motor.
The patent package sold by Tesla included the modern AC induction
motor and the modern AC power grid.
Bill Beaty
> No, it's a method of distribution that is more efficient than single
> phase for the same amount of copper.
What was the point of Westinghouse corp adopting polyphase
transmission? You can speculate all you want, but the history books
make it very clear.
Bill Beaty
> George Herold wrote:
> > On Jun 21, 1:12 am, HardySpicer <gyansor...@gmail.com> wrote:
>
> >> I only wanted the invention of 3 phase, not the rotating magnetic
> >> field or the induction motor.
> >> Maybe Hopkinson then.
>
> > Isn't the 'purpose' of three phase to run induction motors?
>
> less filtering than single-phase.
They were using diodes industrially in 1890?!
Sheesh.
Smoother rectification was a spinoff that happened decades after the
system was up and running.
Bill Beaty
wrote:
> I don't know the timing of things, but one of the earliest AC electrical
> systems was 90 degree 2 phase power.
Tesla, being actually smart, invented "Polyphase," covering all bases.
If someone insinuates that 90deg polyphase was Tesla's invention,
while 60deg polyphase wasn't ...well ...it's a polyphase patent, not
a 90deg polyphase patent.
Ann O'Nymous
Silly question: Is there any advantage to using more phases for power
transmission or motors than the standard three phase power, such as 5
phase or 7 phase? There's an obvious disadvantage - more wires, more
transformers = more things to break.
Did any of the early experimenters experiment with anything weird like 5
phase power?
Spehro Pefhany
wrote:
>On 6/22/2011 12:27 PM, Bill Beaty wrote:
>> On Jun 21, 9:27 am, moro...@world.std.spaamtrap.com (Michael Moroney)
>> wrote:
>>> I don't know the timing of things, but one of the earliest AC electrical
>>> systems was 90 degree 2 phase power.
>>
>> Tesla, being actually smart, invented "Polyphase," covering all bases.
>>
>> If someone insinuates that 90deg polyphase was Tesla's invention,
>> while 60deg polyphase wasn't ...well ...it's a polyphase patent, not
>> a 90deg polyphase patent.
>
>Silly question: Is there any advantage to using more phases for power
>transmission or motors than the standard three phase power, such as 5
>phase or 7 phase? There's an obvious disadvantage - more wires, more
>transformers = more things to break.
Yes-- if you're turning it into DC you can reduce or eliminate the
need for filtering, and electrolytic caps are prone to failure before
most any other bit.
HardySpicer
For Tesla maybe, but three phase was patented elsewhere as I have
pointed out.
HardySpicer
The best compromise for least copper is 3 phase. Just as 50-60Hz is
best for the frequency.
Any higher and the transformers are smaller but there are more line
losses. Any smaller and you get flicker on the lights and the
transformers get bigger!
Hardy
Paul Hovnanian P.E.
Maybe some more. You only need the three legs (or three transformers). The
additional delta secondaries are wound on the same legs. Since the
secondary currents split between the secondary windings, each one can be
wound with smaller wire and take up about the same length on the core as a
single winding feeding a six pulse supply.
--
Paul Hovnanian mailto:Pa...@Hovnanian.com
------------------------------------------------------------------
The only difference in the game of love over the last few thousand years
is that they've changed trumps from clubs to diamonds.
John S
> Seems to be some confusion, I have Oskar Von Miller
>
> http://www.edisontechcenter.org/OskarVonMiller.html
>
> Nikola Tesla
>
> http://en.wikipedia.org/wiki/Nikola_Tesla
>
> and
>
> Galileo Ferraris
>
> http://en.wikipedia.org/wiki/Galileo_Ferraris and
>
> John Hopkinson
>
> http://en.wikipedia.org/wiki/John_Hopkinson
>
>
I did. You want to buy it?
Send money.
John
Tom Potter
"m II" <C...@in.the.hat> wrote in message news:4e01...@news.x-privat.org...
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
>
>> No, it's a method of distribution that is more efficient than single
>> phase for the same amount of copper.
>> of course. Small induction motor can run on single phase
>> with a capacitor start to simulate a second phase.
>
> motor rotation and start-up without commutation or extra windings. The
> ease of motor reversal was also in that initial idea. The rotating
> magnetic field was the MAIN attraction.
>
> The root 3 factor in the volume of power delivery came in later. It
> could be argued that 3 phase distribution happened only because the 3
> phase motors were appealing to industry and most likely caused the end
> of the somewhat dangerous belt and shaft method power distribution in
> factories.
>
>
>
> mike
Good analysis of the history of electrical power.
Before Edison promoted electricity as a power source,
typical factories used water power or a single steam engine
coupled with leather belts
to drive devices like saws, grinders, lathes, mills, etc.
As high starting torque, single phase motors were not available,
Edison promoted D.C. over A.C.
Although Tesla cultists think that Tesla had a falling out with Edison
because of money, it is more likely that he went to Westinghouse
because of their differences about the immediate future
of A.C. and D.C. motors in industry.
Tesla had a great respect for Edison,
and acknowledges that he learned a lot from him.
Considering that Tesla had access to Edison's technology
and joined with a competitive company,
it seems to me that Edison had more to complain about
than Tesla.
The difference between Edison and Tesla was that
Tesla had a fixation on A.C. which he understood better than anyone else,
whereas Edison had customers and investors to satisfy,
and he couldn't wait for the A.C. technology to catch up.
Westinghouse probably linked with Tesla and promoted A.C.
because Edison controlled most of the patents on D.C.
Edison was like Steve Jobs,
in that he had a better feel for what was possible
and the marketplace.
Note that Edison not only ushered in the electric age,
he invented audio and video recording.
In fact, although he also had investors to satisfy,
Tesla's wasted a lot of his money and investor money
on his flights of fantasy.
Being practical and market driven,
the Edison companies switched to A.C.
as A.C. technology improved,
but A.C. technology never evolved to the point
where Tesla or anyone could beam practical amounts
of power from power stations to users.
It would be nice to beam power to all these gadgets
( Ipads, phones, cameras, flashlights, GPS, etc.)
and not have to recharge them.
The following URLs display torque curves
of various kinds of A.C. and D.C. motors.
http://gearmotorblog.wordpress.com/
http://www.powerqualityanddrives.com/torque_constant_horsepower/
As "m II" indicated,
the initial purpose of multiphase
was to get a rotating magnetic field
rather than to distribute power.
--
Tom Potter
-----------------
http://www.prioritize.biz/
http://voices.yuku.com/forums/66
http://tdp1001.wiki.zoho.com/siteindex.zhtml
http://184.105.237.216/~tompotte/
http://tdp1001.wiki.zoho.com
--- Posted via news://freenews.netfront.net/ - Complaints to ne...@netfront.net ---
HardySpicer
But there isn't anywhere practical where anything otehr than 3 phase,
2 phase or single phase is used.
The step from 2 or 3 phase to 4 is trivial. A schoolboy could work it
out.
Hardy
Androcles
"HardySpicer" <gyans...@gmail.com> wrote in message
news:bad5fdb0-00e9-4dce...@d26g2000prn.googlegroups.com...
Hardy
==============================================
DC is very practical. My phone isn't polyphase or < 100 Hz, there
isn't anywhere practical where anything other than DC is used.
The step from transformer to charged battery is trivial, it is called
"rectifier". A schoolboy could work it out.
--Androcles
P E Schoen
> DC is very practical. My phone isn't polyphase or < 100 Hz,
> there isn't anywhere practical where anything other than DC
> is used. The step from transformer to charged battery is trivial,
> it is called "rectifier". A schoolboy could work it out.
Actually DC is making a resurgence for efficient long distance, high voltage
transmission, as it is now very easy to convert DC voltages up or down.
Three phase AC motors are also being found increasingly in small appliances
such as washing machines and food processors, and they first rectify the
incoming AC to DC and then use PWM to create three phase. Most electronics
now use switching supplies which rectify the AC, and would be even more
efficient if powered directly from DC. Lighting and heating work as well on
DC as AC. And DC is somewhat safer than 60 Hz AC which is just about the
most dangerous frequency for causing fatal ventricular fibrillation.
Paul
Bill Beaty
> On Jun 23, 6:19 am, Ann O'Nymous <nob...@nowhere.com> wrote:
>
>
>
> > On 6/22/2011 12:27 PM, Bill Beaty wrote:
>
> > > On Jun 21, 9:27 am, moro...@world.std.spaamtrap.com (Michael Moroney)
> > > wrote:
> > >> I don't know the timing of things, but one of the earliest AC electrical
> > >> systems was 90 degree 2 phase power.
>
> > > Tesla, being actually smart, invented "Polyphase," covering all bases.
>
> > > If someone insinuates that 90deg polyphase was Tesla's invention,
> > > while 60deg polyphase wasn't ...well ...it's a polyphase patent, not
> > > a 90deg polyphase patent.
>
> > Silly question: Is there any advantage to using more phases for power
> > transmission or motors than the standard three phase power, such as 5
> > phase or 7 phase? There's an obvious disadvantage - more wires, more
> > transformers = more things to break.
>
> > Did any of the early experimenters experiment with anything weird like 5
> > phase power?
>
> The best compromise for least copper is 3 phase. Just as 50-60Hz is
> best for the frequency.
But if it's not divisible by three, it drives you crazy until you take
steps to have it changed.
The real question is: why didn't Tesla fight for 66Hz? IT'S ONE
LOUDER.
Bill Beaty
> Actually Tesla only worked for Edison for a short time when he arrived
> in this country. Edison promised him money to fix a certain electrical
> problem and after Tesla fixed it, Edison told him he was joking!
> Tesla took off never to return.
I always ask: what was the problem Tesla was supposed to fix?
Apparently he and another guy redesigned all the Edison equipment.
Earlier it had resembled horse-shoe magnets with a rotor between the
tips. Later it resembled small cylinders spinning within bigger
ones.
Did Tesla do that? If so, then not only did he fill the world with
induction motors. Perhaps he also filled it with DC motors shaped
like cylinders. Tesla, as an accidental sculptor, seemed obsessed
with lathe-turned shapes.
Don't forget that his training was in mechanical engineering.
> The "Tesla" model of the brilliant loner
> inventor has all but vanished (with a couple of notable exceptions
> such as Steinmetz at GE and some others)
Find Norbert Weiner's autobiography "I am a mathematician" for some
interesting dirt on Heaviside's invention of transmission line theory
and "Telegrapher's equation." It's another example of weird loner
geniuses screwed by large corporations. M. Pupin patented Heaviside's
breakthrough, taking the credit (and the huge payment) for making long-
dist comms possible. Weiner tells all, and spits on Pupin's grave.
Preeces' also!
:)
I love the story of the transistor: Shockley told his employees
Bardeen and Brattain to stop wasting time on the point-contact
transistor. So they put it all on a wheeled cart, and kept working on
it. That way they could easily hide it in the disused adjacent office
whenever Shockley was scheduled to be in the lab. "Crystal Fire,"
great book.
Androcles
"P E Schoen" <pa...@pstech-inc.com> wrote in message
news:itus1e$pd$1...@speranza.aioe.org...
"Androcles" wrote in message news:tCBMp.14593$r52....@newsfe02.ams2...
> DC is very practical. My phone isn't polyphase or < 100 Hz,
> there isn't anywhere practical where anything other than DC
> is used. The step from transformer to charged battery is trivial,
> it is called "rectifier". A schoolboy could work it out.
Actually DC
========================================
Don't snip the context or you'll be snipped in return.
"HardySpicer" <gyans...@gmail.com> wrote in message
news:bad5fdb0-00e9-4dce...@d26g2000prn.googlegroups.com...
But there isn't anywhere practical where anything otehr than 3 phase,
2 phase or single phase is used.
The step from 2 or 3 phase to 4 is trivial. A schoolboy could work it
out.
Hardy
========================================
bud--
Interesting to look at old mechanical power installations. Long
jackshafts going through the building with pulleys for power takeoff.
>
> As high starting torque, single phase motors were not available,
> Edison promoted D.C. over A.C.
AC was not considered useful. There weren't ANY AC motors.
>
> Although Tesla cultists think that Tesla had a falling out with Edison
> because of money, it is more likely that he went to Westinghouse
> because of their differences about the immediate future
> of A.C. and D.C. motors in industry.
Apparently Tesla biographers are cultists. They say the falling out was
about not getting paid what Tesla thought Edison had promised. Tesla was
so mad at Edison he left without a job prospect and wound up as a ditch
digger for a while. Westinghouse was much later, after Tesla set up a
laboratory and applied for patents.
>
> Tesla had a great respect for Edison,
> and acknowledges that he learned a lot from him.
I don't think so.
>
> Considering that Tesla had access to Edison's technology
> and joined with a competitive company,
> it seems to me that Edison had more to complain about
> than Tesla.
Fiction.
>
> The difference between Edison and Tesla was that
> Tesla had a fixation on A.C. which he understood better than anyone else,
> whereas Edison had customers and investors to satisfy,
> and he couldn't wait for the A.C. technology to catch up.
> Westinghouse probably linked with Tesla and promoted A.C.
> because Edison controlled most of the patents on D.C.
When Tesla worked for Edison, Edison did not understand advantages in AC
and dismissed it entirely. Not having an understanding of science he
opposed it as it later as AC plants were being installed.
He also opposed it because of his dominance and investment in the DC
power field.
In addition to competing with Edison, Westinghouse saw the advantages in AC.
>
> Edison was like Steve Jobs,
> in that he had a better feel for what was possible
> and the marketplace.
>
> Note that Edison not only ushered in the electric age,
> he invented audio and video recording.
Tesla has all the basic patents for AC motors. You essentially couldn't
make an AC motor without infringing on a Tesla patent.
Tesla also has basic patents in wireless/broadcasting. Marconi
infringed. The decision on Tesla priority was not made (US Supreme
Court) until after Tesla died. I believe you can't make a practical
radio without infringing on a Tesla patent (maybe you can with modern ICs).
Tesla was an inventor, but not a good businessman.
>
> In fact, although he also had investors to satisfy,
> Tesla's wasted a lot of his money and investor money
> on his flights of fantasy.
Tesla did have some 'different' ideas. On the other hand, much of what
he worked on was in unknown fields.
>
> Being practical and market driven,
> the Edison companies switched to A.C.
> as A.C. technology improved,
A gross oversimplification. There were lawsuits and eventually
compromises. By then Edison had been forced out of his company.
Westinghouse also was forced out of his company.
<snip>
Spehro Pefhany
wrote:
>"Androcles" wrote in message news:tCBMp.14593$r52....@newsfe02.ams2...
>
>> DC is very practical. My phone isn't polyphase or < 100 Hz,
>> there isn't anywhere practical where anything other than DC
>> is used. The step from transformer to charged battery is trivial,
>> it is called "rectifier". A schoolboy could work it out.
>
>Actually DC is making a resurgence for efficient long distance, high voltage
>transmission, as it is now very easy to convert DC voltages up or down.
Also, (relatively) short-distance undersea cables, where losses would
be dramatically higher if AC were to be used.
For example: http://en.wikipedia.org/wiki/NorNed
Rich Grise
> On Jun 21, 5:54�pm, Benj <bjac...@iwaynet.net> wrote:
>> Actually Tesla only worked for Edison for a short time when he arrived
>> in this country. Edison promised him money to fix a certain electrical
>> problem and after Tesla fixed it, Edison told him he was joking!
>> Tesla took off never to return.
>
> I always ask: what was the problem Tesla was supposed to fix?
>
get only about half-way across town before the wire resistance
dropped so much voltage that the load couldn't operate properly,
like, light bulbs wouldn't get above dull red and so on.
So Tesla invented AC and the transformer.
The Tesla coil is kinda the "logical" extension of transformer
theory; remember, back in those days they were inventing all
this stuff from scratch - they were the "pioneers," to boldly
go where no man has gone before and all that.
So, with a step-up transformer, you get a higher voltage for
transmission, and the current drops. Well, at 100,000 volts
it only takes 10 mA to transmit a kilowatt. At a million volts,
it takes only a milliamp - at a billion volts, a nanoamp, and
so logically, if he could get an infinite number of volts, you
shouldn't need any wire at all!
Unfortunately, he ran into that little problem where the electrons
like to escape from the high voltage. )-;
Cheers!
Rich
David Lesher
>But there isn't anywhere practical where anything otehr than 3 phase,
>2 phase or single phase is used.
At least one of the massive Detroit area auto plants used to
provide their own 6-phase. (?Willow Run?) This when it had its
own power-house.
Maytag's Neptune washers used 6-phase motors.
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
P E Schoen
news:360192a8-b6a2-4693...@e17g2000prj.googlegroups.com...
There are some interesting opinions on this:
http://wiki.answers.com/Q/Why_is_the_electrical_frequency_for_AC_power_60_Hz_in_the_US_and_50_Hz_in_Europe_and_how_were_the_frequencies_determined
http://wiki.answers.com/Q/Why_60_hz_not_50_hz
http://en.wikipedia.org/wiki/Alternating_current
http://www.physicsforums.com/archive/index.php/t-53692.html
In the early days, there were frequencies as low as 16-2/3 Hz, 25 Hz, and 45
Hz. It was easier to build generators that ran at slower speeds, and large
low speed high torque industrial motors. Higher frequencies required more
poles and thinner laminations which were more difficult to make in the 19th
century. For lighting, 50/60 Hz was about the minimum to eliminate flicker.
The last reference above includes a lengthy and seemingly accurate
assessment of the choice of frequency. It claims that Westinghouse
originally used 133.3 Hz.
There may also be a relationship to phonograph record turntable speeds of
33-1/3 and 16-2/3 RPM, although it does not fully explain 45 RPM (but that
was introduced in the 1950s), but 78 RPM was much earlier:
http://en.wikipedia.org/wiki/Phonograph. I don't know the RPM of the Edison
cylinders, and they were originally hand-cranked. Later Edison electric
phonographs ran on DC.
There is also an interesting theory that 60 Hz was chosen as the most lethal
frequency for the electric chair, although Edison may have started this
rumor when he was expounding on the dangers of AC vs DC.
The perceived loudness of AC hum is also a consideration, and 50/60 Hz is
relatively well tolerated, but 100 Hz or higher is much more objectionable.
Paul
Androcles
"P E Schoen" <pa...@pstech-inc.com> wrote in message
news:iu0cq1$sb7$1...@speranza.aioe.org...
The perceived loudness of AC hum is also a consideration, and 50/60 Hz is
relatively well tolerated, but 100 Hz or higher is much more objectionable.
==================================================
DC doesn't hum.
m II
Hash: SHA1
On 06/23/2011 08:38 AM, bud-- wrote:
>> As high starting torque, single phase motors were not available,
>> Edison promoted D.C. over A.C.
>
> AC was not considered useful. There weren't ANY AC motors.
My 120 volt AC angle grinder works very well on 120 volts DC. The
magic's in the brushes.
Any motor with brushes will work on either type of supply, hence the
name 'universal motor'.
Tesla wanted to get rid of the brushes, as they are maintenance heavy
and waste power.
mike
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Don Lancaster
> HardySpicer<gyans...@gmail.com> writes:
>
>
>> But there isn't anywhere practical where anything otehr than 3 phase,
>> 2 phase or single phase is used.
>
> At least one of the massive Detroit area auto plants used to
> provide their own 6-phase. (?Willow Run?) This when it had its
> own power-house.
>
> Maytag's Neptune washers used 6-phase motors.
>
>
A case can be made that switched reluctance motors are N phase.
And highly likely to shoot the induction motor out of the saddle.
Beats them all to hell on efficiency, lower rpm torque, self-starting,
and variable speed. But you have to get sneaky to avoid physical
feedback sensing devices. Also some stability issues.
--
Many thanks,
Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: d...@tinaja.com
Please visit my GURU's LAIR web site at http://www.tinaja.com
Tom Potter
"bud--" <remove....@isp.com> wrote in message
news:itvj5n$qoh$1...@speranza.aioe.org...
THE AGE OF ELECTRICITY. by Nikola Tesla
"Now I come to an interesting chapter of my life, when I
arrived in America. I had made some improvements in dynamos
for a French company who were getting their machinery from
here. The improved forms were so much better that the
manager of the works said to me: "You must go to America,
and design the machines for the Edison Company." So, after
ineffectual efforts on the other side to get somebody to
interest himself in my plans financially, I came to this
country. I wish that I could only give you an idea how what
I saw here impressed me. You would be very much astonished.
You have a? undoubtedly read those charming Arabian Nights
tales, in which the genie transports people into wonderful
regions, to go through all sorts of delightful adventures.
My case was just the opposite. The genie transported me from
a world of dreams into one of realities. My world was
beautiful, ethereal, as I could imagine it. The one I found
here was a machine world; the contact was rough, but I liked
it. I realized from the very moment I saw Castle Garden that
I was a good American before I landed.
Then came another event. I met Edison,
and the effect he produced upon me was extraordinary.
When I saw this wonderful man, who had had no
theoretical training at all, no advantages, who did all
himself, getting great results by virtue of his industry and
application, I felt mortified that I had squandered my life.
I had studied a dozen languages, delved in literature and
art and had spent my best years in ruminating through
libraries and reading all sorts of stuff that fell into my
hands. I thought to myself, what a terrible thing it was to
have wasted my life in those useless efforts. If I had only
come to America earlier and devoted all of my brain power to
inventive work, what might I have done? In later life
though, I realized I would not have produced anything
without the scientific training I got, and it is a question
whether my surmise as to my possible accomplishment was
correct.
In Edison's works I passed nearly a year of the
most strenuous labor, and then certain capitalists
approached me with the project to form my own company."
Don Lancaster
The likely cause of 45 RPM was the same as the big hole in the middle:
RCA wanted to uniquely supply all of the product.
HardySpicer
> On 6/23/2011 11:48 AM, David Lesher wrote:
>
>
> >> But there isn't anywhere practical where anything otehr than 3 phase,
> >> 2 phase or single phase is used.
>
> > At least one of the massive Detroit area auto plants used to
> > provide their own 6-phase. (?Willow Run?) This when it had its
> > own power-house.
>
> > Maytag's Neptune washers used 6-phase motors.
>
> A case can be made that switched reluctance motors are N phase.
>
1 The switched reluctance motor was invented way before even the
ordinary ac motor
2. the N phases are not supplied to the motor but created at the
receiver end.
Hardy
HardySpicer
>
>
> >> But there isn't anywhere practical where anything otehr than 3 phase,
> >> 2 phase or single phase is used.
>
> > At least one of the massive Detroit area auto plants used to
> > provide their own 6-phase. (?Willow Run?) This when it had its
> > own power-house.
>
> > Maytag's Neptune washers used 6-phase motors.
>
> A case can be made that switched reluctance motors are N phase.
>
> And highly likely to shoot the induction motor out of the saddle.
>
HardySpicer
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 06/23/2011 08:38 AM, bud-- wrote:
>
> >> As high starting torque, single phase motors were not available,
> >> Edison promoted D.C. over A.C.
>
> > AC was not considered useful. There weren't ANY AC motors.
>
> My 120 volt AC angle grinder works very well on 120 volts DC. The
> magic's in the brushes.
>
> Any motor with brushes will work on either type of supply, hence the
> name 'universal motor'.
>
wouldn't work on dc and ac. It works because Torque is prop to current
squared
and this is like a rectifier of sorts.
josephkk
>P E Schoen wrote:
>> "brent" wrote in message
>> news:d4e30129-107e-4467...@y13g2000yqy.googlegroups.com...
>>
>>> The only thing I remember from my power class was that 3 phase
>>> gave constant torque, so I always assumed this was what you
>>> wanted on big machines
>>
>> If you add the squares of the sines of the three phase angles (at 120
>> degrees), for any angular rotation, it will be always 1.5. This means that
>> the total power will be constant.
>
>That was very important in computer mainframe days.
>
>>Torque is proportional to Power/Speed.
>> Speed is generally proportional to voltage, and torque is proportional to
>> current.
For series connected brush motors, perhaps. For induction motors, speed
is a function of frequency primarily.
>>So three phase will provide constant torque.
Nope. Especially not with variable frequency drives.
>>
>> Paul
>>
>
>
>/BAH
Michael A. Terrell
m II wrote:
>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> >
> >> Transformers will not give you extra phases. You can get multiple taps
> >> from a secondary, but those aren't extra phases.
> >>
> >
> >
> > , http://en.wikipedia.org/wiki/Scott-T_transformer >
> >
> >
>
> Well, there's that...but let's see it give us six phase from three...
You use three center tapped transformers. That gives you six phases
at 60 degrees each. The center taps are tied together for the negative,
and the common cathodes are the positive. As stated above, common of
high power transmitters since it requires little filtering.
--
It's easy to think outside the box, when you have a cutting torch.
Michael A. Terrell
Bill Beaty wrote:
>
> On Jun 21, 12:40 pm, Rich Grise <ri...@example.net.invalid> wrote:
> > George Herold wrote:
> > > On Jun 21, 1:12 am, HardySpicer <gyansor...@gmail.com> wrote:
> >
> > >> I only wanted the invention of 3 phase, not the rotating magnetic
> > >> field or the induction motor.
> > >> Maybe Hopkinson then.
> >
> > > Isn't the 'purpose' of three phase to run induction motors?
> >
> > Well, that plus for DC rectification, it takes significantly
> > less filtering than single-phase.
>
> They were using diodes industrially in 1890?!
Electrolyic rectifiers were one of the first availible that would
handle much curent.
Michael A. Terrell
Wanna bet?
Michael A. Terrell
Androcles wrote:
>
> DC is very practical. My phone isn't polyphase or < 100 Hz, there
> isn't anywhere practical where anything other than DC is used.
Your phone only needs a few mA to operate, and the audio is
superimposed on the DC supplied by your Telco. Kind of hard to do if
it's AC powered, isn't it?
Benj
> On 6/23/2011 2:56 PM, P E Schoen wrote:
> > There are some interesting opinions on this:
> >http://wiki.answers.com/Q/Why_is_the_electrical_frequency_for_AC_powe...
I see that everyone is pretty much wandering in circles here including
Don Lancaster.
The Wiki answers are pretty much correct. All the rest is crap. Tesla
did the calculation for transformers (which pretty much held for
motors and generators too) for the best frequency for operation. No,
it wasn't about phonograph speeds (they were spring motors then!) or
mystical numbers, or thickness of laminations in the 19th century, or
electric chairs, or how loud "hum" was (a particularly dumb assertion
in an age of acoustic reproduction) It all had to do with (are you
all ready for this?) MONEY! Put it in the formula. I want to put
distribution transformers all over town. To attain a certain
efficiency given the standard cheap Iron of the day and the amount of
copper needed, what frequency is "best" meaning gives transformers
that cost the least? Tesla calculated 60 Hz. Europeans are said to
have chosen 50 for political reasons though I don't know what the
politics was.
Today cheap iron can be made much better, but the frequencies have
stayed the same by "inertia" I presume. Aircraft typically uses 400 Hz
but takes expensive high quality iron. But there the object isn't
cost, but weight. Modern switching supplies don't use iron at all and
operate at very high audio frequencies.
As for Don's assertions about 45 Rpm records, he should be ashamed of
himself for knowing so little of the history and technology of the 45
after writing so many popular articles for so many years. Sure Big
Corp bashing is fun and typically true, but in this case... RCA
worked on the 45 BEFORE CBS developed the 33 1/3 LP. Basically the
idea was to develop the "ultimate" 78 rpm record. Which is to say a
record that did everything the common 78's did and more. So changing
to a vinyl record they reduced the diameter, and lowered the rpm so
that the recording time of a 78 fit on a 7" record. This lowered
weight, storage space, and cost of the records. To reduce material
even further the records were made thin. But rather than a uniformly
"floppy" record, only the outer band where the track was was reduced
while the label area was left thicker. This made the record stronger
and less flexible, but also provided the technical advantage of not
allowing the recorded surfaces to rub against each other when stacked
on a changer, hence reducing damage and improving record life.
The 45 speed was chosen because they wanted the recording "track" area
to be relatively optimum. On a large LP when you get near the center
the fidelity tend to get worse. This has to do with both the fact that
the linear velocity of the needle over the track is lower but also in
the case of vinyl due to the fact it is soft and tends to "give". This
creates distortion as not the needle is not precisely tracking the
original groove. To reduce these effects, RCA engineers upped the
speed slightly (but still not so much as to not have the full 78
recording time) and also increased the spiral pitch along with
increased cutter excursions. The latter was probably also done to
allow the use of cheaper phonograph pickups in the players they sold.
Later "extended" 45s were also pressed that used standard LP groove
spacing (but still the same 45 rpm speed) to get more recording time
on a 45. (Often for classical singles etc) The point is that much
like the way Tesla came up with 60 Hz as the optimum transformer
frequency, RCA came up with 45 rpm as the optimum record speed for
maximum fidelity with a 7" single with a narrow track at the outside
diameter. (given the state of various recording arts at the time).
Eventually LP technology was improved to where even the most inner
tracks produced quality reproduction.
Which brings us to that large hole that Don is pondering. It was NOT
to "corner the market". Yes, RCA had the 45 and CBS had the LP, but
pretty soon they both were making both kinds and as far as I can
determine nobody sued anybody over it. The large hole had to do with
how record changers worked. Old 78 record changers worked by placing a
stack of records on a small diameter spindle that had an offset in it
a few inches above the turntable. As each record was needed, it was
shoved sideways off the offset to drop down onto the turntable. The
small hole and tiny spindle generally created a pretty short life for
the record hole when used on a changer. So RCA made the hole much
larger and even better used the thicker label area to taper the label
down to a thin thickness again at the hole. This meant that in a stack
of records there were these V shaped grooves between records. A set of
thin blades that came out from the large spindle held the stack up
while the blades holding the bottom record retracted allowing it to
drop. Hence, the ENTIRE changing operation was done right from the
center spindle and the tapered gaps and blades and larger holes meant
you could change these records forever without damage! Since the 45
standards insured all records had the same label thickness one didn't
have the problems that 78 changers often had when dealing with records
of differing thickness.
Remember that RCA/Victor also sold phonographs so if there was any
market cornering, it was in that department.
So the bottom line was the old 78 record was totally perfected. Which
not too many years later was about like building the perfect buggy
whip. Life and times just passed it by.
RCA 45s? HELL! I was there!
brent
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -
I am not quite sure what you are saying, but the constant torque that
I was speaking of was contant torque over the full duration of one
cycle (1/60 second). In other words, the torque does not change based
upon what the phase of the incoming signal is.
Frisbieinstein
> On Jun 20, 10:56 pm, HardySpicer <gyansor...@gmail.com> wrote:
>
> A guy I used to work with had this "seeds" theory about it. His
> "theory" was that when it was time for a new invention in the world,
> the "powers that be" would sort of drop "seeds" for the new idea from
> heaven. They would fall all over the earth. Some inventors would pick
> them up and run with them. Some would sort of give them a look and
> nothing more and others would ignore them or not notice them at all.
> Yes, it's kind of a "joke" theory, but on the other hand it does fit
> the data of the way great inventions commonly happen. It is VERY
> common for 'great" inventions to appear simultaneously in several
> places around the world at the same time!
>
Yeah, I believe that. But inventions are built on previous inventions
combined with need, so it is not surprising that several people would
work in parallel.
A woman once tried to sneak a pistol into an Eric Clapton concert
because she thought he was stealing songs from her on the astral
plane. There's no law against astral theft, so she turned vigilante.
P E Schoen
news:392dnf1x_cLXD5jT...@earthlink.com...
> Bill Beaty wrote:
>> They were using diodes industrially in 1890?!
> Electrolyic rectifiers were one of the first availible that
> would handle much curent.
There were also mechanical rectifiers (and actually a DC dynamo's commutator
is essentially just that)
http://en.wikipedia.org/wiki/Mechanical_rectifier
http://www.aqpl43.dsl.pipex.com/MUSEUM/POWER/mechrect/mechrect.htm
Here's an article that shows how to make a full wave electrolytic rectifier:
http://chestofbooks.com/crafts/popular-mechanics/The-Boy-Mechanic-700-Things-for-Boys-to-Do/How-To-Make-An-Electrolytic-Rectifier.html
And a single phase version that glows and also has a negative resistance
region which generates RF:
http://www.sparkbangbuzz.com/els/borax-el.htm
I seem to recall my father talking about such rectifiers that he built as a
youngster for charging batteries.
Here is an article from 1909 about crystal rectifiers, and a Wiki reference:
http://www.crystalradio.net/minerals/GALENA.PDF (1.4 MB)
http://en.wikipedia.org/wiki/Crystal_detectors
The Wiki article is interesting and there is a humorous picture of a man
with a crystal radio in a corn-cob pipe and wearing an antenna!
http://en.wikipedia.org/wiki/File:Corn_cob_pipe_catwhisker_radio_1922.png
Very interesting...
Paul
HardySpicer
2011> wrote:
> "HardySpicer" <gyansor...@gmail.com> wrote in message
>
> news:bad5fdb0-00e9-4dce...@d26g2000prn.googlegroups.com...
> On Jun 23, 4:27 am, Bill Beaty <bi...@eskimo.com> wrote:
>
> > On Jun 21, 9:27 am, moro...@world.std.spaamtrap.com (Michael Moroney)
> > wrote:
>
> > > I don't know the timing of things, but one of the earliest AC electrical
> > > systems was 90 degree 2 phase power.
>
> > Tesla, being actually smart, invented "Polyphase," covering all bases.
>
> > If someone insinuates that 90deg polyphase was Tesla's invention,
> > while 60deg polyphase wasn't ...well ...it's a polyphase patent, not
> > a 90deg polyphase patent.
>
> 2 phase or single phase is used.
> out.
>
> Hardy
> ==============================================
> DC is very practical. My phone isn't polyphase or < 100 Hz, there
> isn't anywhere practical where anything other than DC is used.
> "rectifier". A schoolboy could work it out.
It is, but long distant transmission is not trivial (or wasn't at the
time).
Hardy
Androcles
Hardy
=================================================
It isn't far from the alternator to the battery in my car although a bridge
rectifier is cheaper than a commutator. I've never heard of AC solar panels.
DC is far more practical than AC, that's why there is so much of it. A
P E Schoen
> I've never heard of AC solar panels.
> DC is far more practical than AC, that's why there is so much
> of it. A schoolboy could work it out.
Actually it can be argued that solar panels are AC, with a period of 24
hours. And higher frequency components when clouds float past the sun or
leaves blowing in the wind change the insolation. Every signal has an AC and
a DC component, and most devices use AC to perform their function, while DC
is mostly used for storing and perhaps transmitting energy. Digital
computers use clocks which are certainly AC, and sequential logic consists
of alternating ones and zeroes. All modern communications use RF. Even DC
motors produce a rotating magnetic field by means of a commutator or
electronics. Lighting and heating may be the only useful purposes where DC
and AC are equally useful and efficient. And it could even be argued that
thermostats and light switches convert the DC to AC with a very low and
variable frequency.
So, what's your point? Can your schoolboy provide a compelling answer?
Paul
bud--
So Telsa was 'star-struck' when he went to work for Edison. He was well
aware of Edison before he came to America. Working for Edison his
opinion changed. He much later noted that if Edison had a basic
scientific background he would likely have come up with a successful
light bulb filament much faster. [Edison did not invent the light bulb
but a practical light bulb that had reasonable life.]
>
> In Edison's works I passed nearly a year of the
> most strenuous labor, and then certain capitalists
> approached me with the project to form my own company."
>
I don't know if Tesla worked in Edison's lab (or if Edison had one his
two famous labs when Tesla worked for him). Tesla was, for a while, a
ditch digger after quitting Edison. He was a good inventor, but notably
poor at developing commercial uses for his inventions (unlike Edison).
Like for instance wireless/radio, where Tesla has some of the base
patents. I don't remember the "capitalists" had anything to do with
Edison. I have not seen anything that indicates Tesla gained
particularly from working for Edison.
bud--
> Bill Beaty wrote:
>> On Jun 21, 5:54 pm, Benj<bjac...@iwaynet.net> wrote:
>>> Actually Tesla only worked for Edison for a short time when he arrived
>>> in this country. Edison promised him money to fix a certain electrical
>>> problem and after Tesla fixed it, Edison told him he was joking!
>>> Tesla took off never to return.
>>
>> I always ask: what was the problem Tesla was supposed to fix?
>>
> Well, for one, the transmission distance problem. Edison's DC could
> get only about half-way across town before the wire resistance
> dropped so much voltage that the load couldn't operate properly,
> like, light bulbs wouldn't get above dull red and so on.
Half way across town would be a small town
>
> So Tesla invented AC and the transformer.
Others invented the transformer. Tesla came up with the concept of the
rotating magnetic field in an AC motor, and essentially all the
variations of AC motors. And multiphase, or major parts of it.
>
> The Tesla coil is kinda the "logical" extension of transformer
> theory; remember, back in those days they were inventing all
> this stuff from scratch - they were the "pioneers," to boldly
> go where no man has gone before and all that.
I wish I knew more about Tesla coils. They are different from ordinary
transformers in that the primary, and I think the secondary, are
resonant circuits. And I think the length of the secondary is 1/4
wavelength.
Tesla certainly "pioneered" in many areas.
Androcles
"Androcles" wrote in message news:%VuNp.1539$%x2....@newsfe17.ams2...
> I've never heard of AC solar panels.
> DC is far more practical than AC, that's why there is so much
> of it. A schoolboy could work it out.
As you decided to snip the context of my statement I've returned the
complement and carefully and courteously snipped the rest of yours
so that I have space to restore mine.
On Jun 23, 7:06 pm, "Androcles" <Headmas...@Hogwarts.physics.June.
2011> wrote:
> "HardySpicer" <gyansor...@gmail.com> wrote in message
>
> news:bad5fdb0-00e9-4dce...@d26g2000prn.googlegroups.com...
> On Jun 23, 4:27 am, Bill Beaty <bi...@eskimo.com> wrote:
>
> > On Jun 21, 9:27 am, moro...@world.std.spaamtrap.com (Michael Moroney)
> > wrote:
>
> > > I don't know the timing of things, but one of the earliest AC
> > > electrical
> > > systems was 90 degree 2 phase power.
>
> > Tesla, being actually smart, invented "Polyphase," covering all bases.
>
> > If someone insinuates that 90deg polyphase was Tesla's invention,
> > while 60deg polyphase wasn't ...well ...it's a polyphase patent, not
> > a 90deg polyphase patent.
>
> But there isn't anywhere practical where anything otehr than 3 phase,
> 2 phase or single phase is used.
> The step from 2 or 3 phase to 4 is trivial. A schoolboy could work it
> out.
>
> Hardy
> ==============================================
> DC is very practical. My phone isn't polyphase or < 100 Hz, there
> isn't anywhere practical where anything other than DC is used.
> The step from transformer to charged battery is trivial, it is called
> "rectifier". A schoolboy could work it out.
> --Androcles
It is, but long distant transmission is not trivial (or wasn't at the
time).
Hardy
================================================
Now, what were you saying?
upsid...@downunder.com
<ri...@example.net.invalid> wrote:
>> I always ask: what was the problem Tesla was supposed to fix?
>>
>Well, for one, the transmission distance problem. Edison's DC could
>get only about half-way across town before the wire resistance
>dropped so much voltage that the load couldn't operate properly,
>like, light bulbs wouldn't get above dull red and so on.
Apparently Edison was trying to promote incandescent lamps and since
making a long lasting filament in those days for anything higher than
55 or 110 V forced to use such ridiculously low distribution voltages.
Edison was essentially a incandescent lamp salesman, not an electric
distribution engineer :-).
However, arc lights work well also in serial circuits, for instance a
nominally 6 A circuit across the town. When powered by a 1500 Vdc it
could power about 30 arc lamps in series.
Bill Beaty
> "Michael A. Terrell" wrote in messagenews:392dnf1x_cLXD5jT...@earthlink.com...
> > Bill Beaty wrote:
> >> They were using diodes industrially in 1890?!
> > Electrolyic rectifiers were one of the first availible that
> > would handle much curent.
In wide use in 1890?! (1886?!) Says who?
> There were also mechanical rectifiers (and actually a DC dynamo's commutator
> is essentially just that)http://en.wikipedia.org/wiki/Mechanical_rectifierhttp://www.aqpl43.dsl.pipex.com/MUSEUM/POWER/mechrect/mechrect.htm
But the point of this message was regarding the reasons behind the
choice to use 3-phase.
Look at the dates involved, 1887-89, see if they support the idea that
"ease of rectification" was an important issue for the first Tesla/
Westinghouse distribution grids. It wasn't. The polyphase induction
motor and the grid came first. Yes, other benefits became obvious
once it was being used.
>
> Here's an article that shows how to make a full wave electrolytic rectifier:http://chestofbooks.com/crafts/popular-mechanics/The-Boy-Mechanic-700...
So you're saying that these were in wide use industrially prior to
1887? And therefore they influenced Westinghouse to fund Tesla's
multi-phase AC grid? Evidence?
P E Schoen
> On Jun 25, 1:48 pm, "P E Schoen" <p...@pstech-inc.com> wrote:
>> "Michael A. Terrell" wrote in
>> messagenews:392dnf1x_cLXD5jT...@earthlink.com...
>> > Bill Beaty wrote:
>> >> They were using diodes industrially in 1890?!
>> > Electrolyic rectifiers were one of the first availible that
>> > would handle much curent.
> In wide use in 1890?! (1886?!) Says who?
I never said that, and neither did Michael Terrell.
>> There were also mechanical rectifiers (and actually a DC dynamo's
>> commutator is essentially just that)
> But the point of this message was regarding the reasons behind
> the choice to use 3-phase.
> Look at the dates involved, 1887-89, see if they support the idea
> that "ease of rectification" was an important issue for the first
> Tesla/Westinghouse distribution grids. It wasn't. The polyphase
> induction motor and the grid came first. Yes, other benefits
> became obvious once it was being used.
I agree. I was only following the drift about the secondary advantage of
low-ripple rectification, and the early types of rectifiers.
>> Here's an article that shows how to make a full wave electrolytic
>> rectifier:
> So you're saying that these were in wide use industrially prior to
> 1887? And therefore they influenced Westinghouse to fund
> Tesla's multi-phase AC grid? Evidence?
No, I am not saying that at all.
Paul
P E Schoen
> As you decided to snip the context of my statement I've returned
> the complement and carefully and courteously snipped the rest
> of yours so that I have space to restore mine.
Oh, thank you! How "complementary" of you. So you have NPN and PNP parts,
eh?
> Now, what were you saying?
Mostly you need to learn how to quote and provide proper attribution. A
schoolboy can do that. You? Not so much...
Paul
Michael A. Terrell
P E Schoen wrote:
>
> "Michael A. Terrell" wrote in message
> news:392dnf1x_cLXD5jT...@earthlink.com...
>
>
> ?? They were using diodes industrially in 1890?!
>
> ? Electrolyic rectifiers were one of the first availible that
> ? would handle much curent.
>
> There were also mechanical rectifiers (and actually a DC dynamo's commutator
> is essentially just that)
> http://en.wikipedia.org/wiki/Mechanical_rectifier
> http://www.aqpl43.dsl.pipex.com/MUSEUM/POWER/mechrect/mechrect.htm
>
> Here's an article that shows how to make a full wave electrolytic rectifier:
> http://chestofbooks.com/crafts/popular-mechanics/The-Boy-Mechanic-700-Things-for-Boys-to-Do/How-To-Make-An-Electrolytic-Rectifier.html
>
> And a single phase version that glows and also has a negative resistance
> region which generates RF:
> http://www.sparkbangbuzz.com/els/borax-el.htm
>
> I seem to recall my father talking about such rectifiers that he built as a
> youngster for charging batteries.
>
> Here is an article from 1909 about crystal rectifiers, and a Wiki reference:
> http://www.crystalradio.net/minerals/GALENA.PDF (1.4 MB)
> http://en.wikipedia.org/wiki/Crystal_detectors
>
> The Wiki article is interesting and there is a humorous picture of a man
> with a crystal radio in a corn-cob pipe and wearing an antenna!
> http://en.wikipedia.org/wiki/File:Corn_cob_pipe_catwhisker_radio_1922.png
>
> Very interesting...
Yes, considering what little was know about electricity at the time.
You wonder how they came up with some of those ideas.
Have you ever seen the radio built on a pith helmet, using miniature
tubes? There was an article in a early electonics hobby magazine with
the plans. One man on rec.antiques.radio+phono built one a few years
ago, and posted a photo to the binary group they used.
Michael A. Terrell
Androcles wrote:
>
> It isn't far from the alternator to the battery in my car although a bridge
> rectifier is cheaper than a commutator.
Sigh. Cars use alternators to provide current at lower RPMs and to
eliminate brush/commutator failure. Smooth sliprings and brushes last a
lot longer. Old cars with a generator had dim headlights at an idle,
and you could run the battery down if the vehicle idled too long. The
battery was only charged at driving speeds.
josephkk
Oh shit, all those shunt wound brush motors didn't work on AC? Then they
couldn't have worked on DC either. DC vs AC does not really change the
physics of brush motors.
Michael A. Terrell
josephkk wrote:
>
> Oh shit, all those shunt wound brush motors didn't work on AC? Then they
> couldn't have worked on DC either. DC vs AC does not really change the
> physics of brush motors.
Just don't try to run a dynamotor on AC. I made that mistake 40 years
ago. It ran less than one RPM, and never ran right on DC again. At
least it was a useless HV model from an early aircraft RADAR. They were
all over the place for a dollar or two at that time.
josephkk
<mike.t...@earthlink.net> wrote:
>
>josephkk wrote:
>>
>> Oh shit, all those shunt wound brush motors didn't work on AC? Then they
>> couldn't have worked on DC either. DC vs AC does not really change the
>> physics of brush motors.
>
>
> Just don't try to run a dynamotor on AC. I made that mistake 40 years
>ago. It ran less than one RPM, and never ran right on DC again. At
>least it was a useless HV model from an early aircraft RADAR. They were
>all over the place for a dollar or two at that time.
Depolarized it. Fixable with what you know now.
josephkk
wrote:
<snip>
>
>The Wiki answers are pretty much correct. All the rest is crap. Tesla
>did the calculation for transformers (which pretty much held for
>motors and generators too) for the best frequency for operation. No,
>it wasn't about phonograph speeds (they were spring motors then!) or
>mystical numbers, or thickness of laminations in the 19th century, or
>electric chairs, or how loud "hum" was (a particularly dumb assertion
>in an age of acoustic reproduction) It all had to do with (are you
>all ready for this?) MONEY! Put it in the formula. I want to put
>distribution transformers all over town. To attain a certain
>efficiency given the standard cheap Iron of the day and the amount of
>copper needed, what frequency is "best" meaning gives transformers
>that cost the least? Tesla calculated 60 Hz. Europeans are said to
>have chosen 50 for political reasons though I don't know what the
>politics was.
>
>Today cheap iron can be made much better, but the frequencies have
>stayed the same by "inertia" I presume. Aircraft typically uses 400 Hz
>but takes expensive high quality iron. But there the object isn't
>cost, but weight. Modern switching supplies don't use iron at all and
>operate at very high audio frequencies.
In many senses, money, in particular sunk capital, has inertia. Consider
the sunk capital value of all the distribution transformers around the
country. Or any country. Takes a lot of "push" for a long time to get it
to move.
>
<snip>
??=))
josephkk
wrote:
Not the typical usage. Normal usage is versus speed or load.
?-/
P E Schoen
news:5246aedf-33f1-4bab...@b21g2000yqc.googlegroups.com...
> I am not quite sure what you are saying, but the constant torque
> that I was speaking of was contant torque over the full duration
> of one cycle (1/60 second). In other words, the torque does not
> change based upon what the phase of the incoming signal is.
This is also known as "torque ripple" or "speed ripple", and it affects how
smoothly the motor will operate certain sensitive loads, especially at low
RPM, such as power steering. It also contributes to audible noise. Here is
some information:
http://www.scribd.com/doc/22894004/53-DIRECT-TORQUE-CONTROL-OF-INDUCTION-MOTOR-WITH-FUZZY-MINIMIZATION-TORQUE-RIPPLE
http://www.icgst.com/acse/Volume6/Issue4/P1110644003.pdf
http://www.ijest.info/docs/IJEST11-03-02-051.pdf
http://yu.ac.kr/~dclee/papers/international/conference/PEDS07%20torque%20ripple%20elimination%20for.pdf
http://www.freepatentsonline.com/4868438.html
http://www.2dix.com/pdf-2011/torque-ripple-minimization-in-induction-motor-foc-propulsion-pdf.php
Paul
Michael A. Terrell
The commutator had over 100 segments and two sets of brushes, so it
would have been interesting. It's a lot easier with a big electromagnet
like they used to 'charge' the magneto on early one cylinder 'Hit or
Miss' engines. I had a neighbor who built them and sold them at antique
engine shows. His prize possession was a photo of an engine he'd
rebuilt, with 'Grandpa Jones' and the check he wrote to buy it.
Charlie E.
wrote:
Actually, AC solar panels are the coming thing! You put a
micro-inverter on each panel so that you save the costs of one big
inverter...
Charlie
HardySpicer
You've never studied EE I presume?
The idea behind ac is that you can easily scale up or down the
voltage.
High voltage less current equals less losses in transmission. Scaling
dc is a different matter.
Much harder than a transformer and only recently practical.
Hardy
Benj
> On Jun 21, 5:54 pm, Benj <bjac...@iwaynet.net> wrote:
>
> > Actually Tesla only worked for Edison for a short time when he arrived
> > in this country. Edison promised him money to fix a certain electrical
> > problem and after Tesla fixed it, Edison told him he was joking!
> > Tesla took off never to return.
>
>
> Earlier it had resembled horse-shoe magnets with a rotor between the
> tips. Later it resembled small cylinders spinning within bigger
> ones.
>
> Did Tesla do that? If so, then not only did he fill the world with
> induction motors. Perhaps he also filled it with DC motors shaped
> like cylinders. Tesla, as an accidental sculptor, seemed obsessed
> with lathe-turned shapes.
>
> Don't forget that his training was in mechanical engineering.
A lot of speculation here much as same by Potter. The historical
record was that the problem had to do with Edison's Dynamos. I have no
evidence that it had to do with "horseshoe shaped magnets" or not, but
that WAS a large problem of the age.
By using a large horseshoe magnet with an armature between the pole
ends, one creates a VERY inefficient "magnetic circuit". That of
course, creates a very inefficient generator or motor. Just by looking
at the motors and generators Tesla built in his lab, a modern engineer
(who now understands the parameters of magnetics) can quickly
recognize his tight and efficient designs. To ascribe that to just a
love of lathe-turned shapes and to thus imply that the designs were an
accident rather than due to Tesla's understanding of magnetic circuits
is pure and improbable speculation.
Just what is it about Tesla and his inventions that have so many
establishment people (and those who quote them) so hot to totally
discredit Tesla EVEN TODAY? This is a HUGE arrow pointing to
something VERY important apparently hidden there!
Benj
> >Today cheap iron can be made much better, but the frequencies have
> >stayed the same by "inertia" I presume. Aircraft typically uses 400 Hz
> >but takes expensive high quality iron. But there the object isn't
> >cost, but weight. Modern switching supplies don't use iron at all and
> >operate at very high audio frequencies.
>
> In many senses, money, in particular sunk capital, has inertia. Consider
> the sunk capital value of all the distribution transformers around the
> country. Or any country. Takes a lot of "push" for a long time to get it
> to move.
Exactly. There is a Tesla story* about him spouting off to J.P. Morgan
in his typical style about his "wireless" power distribution schemes.
"My invention will make a scrap heap of all existing distribution
equipment" (or words to that effect) Tesla promoted. J.P. just quietly
said, "That will be one huge scarp heap!" And Tesla immediately got
his meaning. Inertia.
The historical record of what Tesla actually did is rather distorted.
And it's distorted for two reasons. One is the general tendency of
Tesla to promote himself and his inventions with very "showbiz" style
exaggerations. And the other is the long term policy started by Morgan
and other robber barons and continued to this day to discredit Tesla
and his inventions. Mention Tesla on the internet and debunkers
immediately descend calling him crazy and minimizing all his
inventions. Even his very popular biographies it seems were put under
pressure to be rewritten several times before finally published.
Clearly Tesla and his inventions REALLY were/are of interest to power-
elite. One example of Tesla himself muddying the waters was his huge
tower for "wireless energy transmission". At the time Tesla was
promoting it as a power station, but much later in court he testified
under oath that in reality it was a transatlantic radio station. Given
the great need at the time for transatlantic communications, it was
amazing that Morgan pulled the funding on what would have surely been
a great money-maker. It's only been slowly that some of these
"stories" have begun to be sorted out.