Electrical Engineering - rotatig magnetic field

Author

rotatig magnetic field

Mitian

2007-09-03, 11:11 am

I want someone who can help me to easly understand how rotating
magnetic field is created in induction motors.If you can it would
good with drawing and mathematical analysis. thank you...

Salmon Egg

2007-09-03, 1:25 pm

On 9/3/07 12:14 AM, in article
1188803681.530954.48610@o80g2000hse.googlegroups.com, "Mitian"
<abrahamizan@yahoo.com> wrote:

> I want someone who can help me to easly understand how rotating
> magnetic field is created in induction motors.If you can it would
> good with drawing and mathematical analysis. thank you...
>
How about someone flying to meet you to explain in person? What have you
done so far to find out for yourself?

Bill
--
If intelligent design trumps evolution, please explain hemorrhoids.

Don Kelly

2007-09-04, 3:25 am

----------------------------
"Mitian" <abrahamizan@yahoo.com> wrote in message
news:1188803681.530954.48610@o80g2000hse.googlegroups.com...
>I want someone who can help me to easly understand how rotating
> magnetic field is created in induction motors.If you can it would
> good with drawing and mathematical analysis. thank you...
>
You can do this crudely with a few minutes of sketching on your own.
consider two concentrated coils at right angles to each other and current in
one coil effectively producing a field perpendicular to the field produced
by current in the other. Now consider one coil has current Icoswt and the
other Isinwt and look at the vector resultant of the two fields at different
times.

You can extend this to 3 phase and you can also do it mathematically.

If you have problems with this- contact me as I do have some pertinent
material but it is better for you to do some discovery for yourself. It
isn't difficult.

Hint -there are many elementary machines texts which deal with this.

--

Don Kelly dhky@shawcross.ca
remove the X to answer

phil-news-nospam@ipal.net

2007-10-10, 3:25 am

On Mon, 03 Sep 2007 00:14:41 -0700 Mitian <abrahamizan@yahoo.com> wrote:

| I want someone who can help me to easly understand how rotating
| magnetic field is created in induction motors.If you can it would
| good with drawing and mathematical analysis. thank you...

The field is created by current in the various coils arranged in a circle.
The phases are connected so that each current peak of a given polarity
follows in sequence around the circle. The is easy with 3 phase power,
where coils opposite each other (180 degrees) are connected to the same
phase source, but in opposite polarity. With 6 such coils it should be
easily seen (understood) to be a fairly uniform field with N and S on
opposite sides that rotates in the power supply frquency.

Now once you have the field rotating, the change induces current in the
initially stationary "squirrel cade" rotor. That induced current then
caues a field that pulls the rotor to follow the field. I can't follow
it as fast as the field turns, however, because there is a speed in which
the dimishing field change as seen by the rotor because it is rotating
will cause it to slow down. It will reach an equalibrium at some point
based on stator field strength, mechanical load, etc.

--
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| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
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