[extropy-chat] eurpoean vs american electric power standards

Mike Lorrey mlorrey at yahoo.com
Mon Jun 27 16:58:27 UTC 2005


According to wikipedia, Tesla chose 60 hertz as the lowest frequency
that would not cause streetlights to flicker visibly to most people
(there is a small percent of people who can detect flicker up to above
100 hertz). Europe and everyone else chose 50 Hz because of the
predeliction of metric countries to use 1 2 5 10 number structures.

"Other frequencies were somewhat common in the first half of the 20th
century, and remain in use in isolated cases today, often tied to the
60 Hz system via a a rotary converter or static inverter frequency
changer. 25 Hz power was used in Ontario, Quebec, the northern USA, and
for electrified railroads. In the 1950's, much of this electrical
system, from the generators right through to household appliances, was
converted and standardised to 60 Hz. Some 25 Hz generators are still in
use at Niagara Falls for large industrial customers who did not want to
replace existing equipment. The lower frequency eases the design of low
speed electric motors, particularly for hoisting, crushing and rolling
applications, and commutator-type traction motors for applications such
as railways, but also causes a noticeable flicker in incandescent
lighting. 16.67 Hz power (1/3 of the mains frequency) is still used in
some European rail systems, such as in Sweden and Switzerland."

400 Hz systems used in aircraft came about because of jet engine
technology, as turbines operate in tens of thousands of rpms, which is
hard to mechanically step down too much to 60 hz. You can generate more
power at 400 hz with a given generator weight than a 60 hz genset of
equal weight. The Constant Speed Drives used to step down shaft speeds
for the generator are near optimal weight (vs generator weight) at 400
hz as well.

Yes, it also allows for lighter guage wire, which is also why aircraft
use 24 vdc or higher direct current voltages as well rather than 12 vdc
as is typical for cars. It is notable that cars are now moving to
higher voltages to save weight in wiring as a fuel economy measure.



--- spike <spike66 at comcast.net> wrote:

> Hey cool, epiphany!
> 
> I have always known that European nations use 50 Hz in
> power distribution, whereas the US and Canada use 60 Hz.
> I never gave any thought to why that is that way until I had
> a waay insightful moment this weekend.  I was installing a ceiling
> fan for my brother-in-law.  This being very close to the
> summer solstice and the house being in Los Angeles, you
> can imagine how hot it was up there in the attic.  This
> was compounded by my insistence on a belt-and-suspenders
> installation, for I do not wish to learn that my brother-
> in-law and his wife had been injured or seriously killed
> by a falling ceiling fan.  Either way, I was a totally
> soaked sweat monster afterwards.
> 
> In any case, after the lengthy and laborious installation
> of this none-too-high-quality fan from Walmart, we turned
> it on for a smoke test, only to find that the 60 Hz hum
> rendered the device practically useless.
> 
> We all know about the 60 Hz hum, or 50 Hz if you are in
> Europe or Australia, or pretty much anywhere except in
> the Americas and Saudi Arabia.
> 
> http://users.pandora.be/worldstandards/electricity.htm
> 
> Transformers make that hum, electric motors, sometimes
> florescent lighting, refrigerators, a lot of stuff.  We
> know the pitch.  For the trained musician, we also know
> that the 60 Hz pitch isn't one of the standard notes.  It
> is hard to reproduce on the saxophone: I have always known
> that the 60Hz pitch is about halfway between a B and a B-flat.
> It sounds exactly halfway between to my ear.  It is a
> very irritating noise because of that.  They should have
> made it either a B or a B flat!  But not exactly halfway
> between
> 
> I know there are a lot of good arguments about efficiency 
> of power transmission, and the amount of copper needed 
> in transformers, etc.  In the rocket science business we 
> often use 400 Hz alternating current to transmit power,
> which requires less mass in copper wire and less iron in 
> the transformers.  But hang on.
> 
> I calculated it and found that 50 Hz would be between
> a G and a G-sharp, but it would be closer to a nice
> honest G.  That somewhat sharp G pitch is more pleasant 
> than an icky sharp B natural or a barfy flat B flat.
> 
> Please those who are musicians and have traveled in
> both the US and otherwise, such as Emlyn Oregan, Damien,
> and others, is the refrigerator hum in Europe more
> pleasant than in the states?
> 
> I'm guessing Tesla wasn't a musician.
> 
> spike 
> 
> 
> 
> 
> 
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Mike Lorrey
Vice-Chair, 2nd District, Libertarian Party of NH
"Necessity is the plea for every infringement of human freedom.
It is the argument of tyrants; it is the creed of slaves."
                                      -William Pitt (1759-1806) 
Blog: http://intlib.blogspot.com

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