Mains transformer weights

Jim Hawkins

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Jan 16, 2012, 10:40:41 AM1/16/12

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Is a mains transformer designed for 60Hz significantly lighter than one of
the same VA rating designed for 50Hz ?

Jim Hawkins

PeterD

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Jan 16, 2012, 11:36:04 AM1/16/12

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Significantly? No... One for 400 Hz would however.

--
I'm never going to grow up.

k...@att.bizzzzzzzzzzzz

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Jan 16, 2012, 11:56:58 AM1/16/12

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On Mon, 16 Jan 2012 15:40:41 -0000, "Jim Hawkins" <jimha...@manx.net> wrote:

>Is a mains transformer designed for 60Hz significantly lighter than one of
>the same VA rating designed for 50Hz ?

About 20%. Is that significant?

Jamie

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Jan 16, 2012, 7:37:17 PM1/16/12

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not really a lot of difference..
~ 17% lighter.
But you must remember that many places where 50Hz
is used, the voltages are a little different so one
transformer could conceivably be used for both. It
most likely wouldn't pass a local ordinance rule due
to a name plate not agreeing.

For example, not to long ago I approved a motor to be
used in a 480 60hz application where the name plate was
as a ~400 v 50hz unit.
End results was the same, with the exception of a little higher
RPM than marked on the ID of course.

Just think V/hz ratio.

Jamie

PeterD

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Jan 17, 2012, 6:27:27 AM1/17/12

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It is also not uncommon for smaller power transformers to be rated as
50/60 hz, too. The dual rating means that there is one less item that
they have to manage in the inventory and manufacturing process.

Jim Hawkins

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Jan 21, 2012, 9:51:55 AM1/21/12

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Following on from this, why is it that electricity generation is limited to
such low frequencies as 50 or 60 Hz ?
As the frequency rises, the energy lost through electromagnetic radiation
from the wires rises, but is it really a significant amount ? Would it be
significant at 1 kHz ? If not, why isn't generation done at that sort of
frequency ? The savings in transformer weights and sizes everywhere would
be enormous. Is it because of mechanical engineering limitations on the
rotational speeds of the large rotary generators the power stations use ?

k...@att.bizzzzzzzzzzzz

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Jan 21, 2012, 10:53:11 AM1/21/12

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On Sat, 21 Jan 2012 14:51:55 -0000, "Jim Hawkins" <jimha...@manx.net> wrote:

>Jim Hawkins wrote:
>> Is a mains transformer designed for 60Hz significantly lighter than
>> one of the same VA rating designed for 50Hz ?
>>
>> Jim Hawkins
>
>Following on from this, why is it that electricity generation is limited to
>such low frequencies as 50 or 60 Hz ?

Losses. Mechanics.

>As the frequency rises, the energy lost through electromagnetic radiation
>from the wires rises, but is it really a significant amount ?

Yes.

>Would it be significant at 1 kHz ?

Yes, certainly.

>If not, why isn't generation done at that sort of frequency ?
>The savings in transformer weights and sizes everywhere would
>be enormous. Is it because of mechanical engineering limitations on the
>rotational speeds of the large rotary generators the power stations use ?

Partly. 1kHz translates to a 60,000 RPM generator. That's kinda high for a
generator of a useful size (60Hz = 3600RPM, much better). Multipole
generators are possible, but that only reduces this linearly and increases the
size similarly.

tm

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Jan 21, 2012, 11:10:06 AM1/21/12

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<k...@att.bizzzzzzzzzzzz> wrote in message
news:rhnlh7pbb5rpbb6qr...@4ax.com...

Instead of hum, you would have whine.

k...@att.bizzzzzzzzzzzz

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Jan 21, 2012, 11:52:37 AM1/21/12

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Good point. Perhaps it should be 20kHz. ;-)

tm

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Jan 21, 2012, 12:07:46 PM1/21/12

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<k...@att.bizzzzzzzzzzzz> wrote in message
news:v9rlh75ksbe5uvhku...@4ax.com...

Hmmm, waveguide at 133kv. Sounds like that would qualify for an energy
department grant.

Uwe Hercksen

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Jan 26, 2012, 6:12:07 AM1/26/12

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Jim Hawkins schrieb:

> Following on from this, why is it that electricity generation is limited to
> such low frequencies as 50 or 60 Hz ?

Hello,

400 Hz is used for electric power distribution in airplanes, but if we
would use this frequency for terrestic distribution, problems with
transmission line effects would be much worse. If an AC generator would
feed a distribution line with the length of a quarter wavelength, the
voltage at the other end would rise infinitly. This is called Ferranti
effect:
http://en.wikipedia.org/wiki/Ferranti_effect

Bye

Michael A. Terrell

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Jan 26, 2012, 1:22:23 PM1/26/12

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tm wrote:
>
> Instead of hum, you would have whine.

Like a lot of Usenet posts. ;-)

--
You can't have a sense of humor, if you have no sense.

tm

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Jan 26, 2012, 2:28:29 PM1/26/12

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"Michael A. Terrell" <mike.t...@earthlink.net> wrote in message
news:7tmdnY45-5R9BLzS...@earthlink.com...

Ha. I have a sticker on my helmet that says "Stop Global Whining". :)

Regards, etc.

Sjouke Burry

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Jan 26, 2012, 6:50:39 PM1/26/12

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"Jim Hawkins" <jimha...@manx.net> wrote in
news:uZ6dnX1KQIiQTIfS...@supernews.com:

I have worked in the airforce, they also used 400 Hz
on(or under) the ground.
You could hear the 3rth harmonic(1200 Hz) all over the
place, wich is not such a good idea in your home.
Very iritating for new workers, old workers had a
measurable dip in their hearing curve, and could not
hear that frequency anymore.Permanent damage.

Message has been deleted

PeterD

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Jan 28, 2012, 7:37:24 AM1/28/12

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On 1/27/2012 12:42 PM, Fred Abse wrote:

> On Sat, 21 Jan 2012 10:53:11 -0500, k...@att.bizzzzzzzzzzzz wrote:
>
>> Partly. 1kHz translates to a 60,000 RPM generator. That's kinda high for a
>> generator of a useful size (60Hz = 3600RPM, much better). Multipole
>> generators are possible, but that only reduces this linearly and increases the
>> size similarly.
>
>

> https://secure.wikimedia.org/wikipedia/en/wiki/Alexanderson_alternator
>
>

Huh? Where does anyone say 1kHz translates to a 60K RPM? The speed and
frequency are not related, the speed and the number of poles in a
generator head determine the frequency. Most 400 Hz generator sets run
at 2000 RPM. Your flawed concept would have them running at 24K RPM!

Michael A. Terrell

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Jan 28, 2012, 12:35:43 PM1/28/12

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Now you've gone and done it! Very few people remember that
Alexanderson Alternators were used as very early keyed transmitters,
when 'Spark was king!' They have never seen anything like
Alexanderson's designs, and the concept isn't covered in any book on
motors I've ever seen. I learned about them, years ago while studying
early radio.

Message has been deleted

PeterD

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Jan 30, 2012, 8:29:41 AM1/30/12

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On 1/28/2012 1:45 PM, Fred Abse wrote:

> Read the link:
>
> Not *my* concept.
>
> Goes back to about 1903. about a dozen or so installed worldwide.
> Most decommissioned before and during WWII.
>
> There's one in Sweden that still gets run up, once a year.
>
> *I* never claimed that 1kHz translates to *any* RPM. That was someone else.
>
> What is a generator "head", BTW?
>
>
>

OK, not your idea, sorry I implied that. (Or said it, as the matter may
be!)

A generator head is the part that makes the electricity, and is
(typically) attached to an engine or other motivating device (water
wheel or turbine).

Message has been deleted

Cydrome Leader

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Feb 26, 2012, 7:58:21 PM2/26/12

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Apparently they had line frequencies as 16.66 Hz and other strange stuff
like 25Hz, which was last used in the US for railway lines.

Here's a little about this:

http://www.nycsubway.org/articles/rotary_converter.html

josephkk

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May 20, 2012, 4:23:26 PM5/20/12

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I had dips at 2400 and 4800 Hz as well as 1200 when i was done with the
navy.

?-)