What kid of motor is this?

A motor was described to me today that looks like the typical shaded
pole motor that used to be found in old phonographs. It just has one
winding with only two wires. But the rotor is strongly magnetized. I
don't know if there is the shorted winding typical of shaded pole
motors. The motor is a pump motor in a washing machine and so it
presumably needs to turn the same direction all the time.
Thanks,
Eric

 

[Jasen Betts]

On 2015-12-07, etpm@whidbey.com <etpm@whidbey.com> wrote:

A motor was described to me today that looks like the typical shaded
pole motor that used to be found in old phonographs. It just has one
winding with only two wires. But the rotor is strongly magnetized. I
don't know if there is the shorted winding typical of shaded pole
motors. The motor is a pump motor in a washing machine and so it
presumably needs to turn the same direction all the time.
Thanks,
Eric

sounds like some sort of synchronous motor.

--
\_(ツ)_

 

[Massoud]

etpm@whidbey.com wrote in news:v66c6bdanki35n8prhbvbn7g0tlpvobqam@4ax.com:

A motor was described to me today that looks like the typical shaded
pole motor that used to be found in old phonographs. It just has one
winding with only two wires. But the rotor is strongly magnetized. I
don't know if there is the shorted winding typical of shaded pole
motors. The motor is a pump motor in a washing machine and so it
presumably needs to turn the same direction all the time.
Thanks,
Eric

That single loop copper wire generates magnetic phase shift for rotation.
The rotor should not be magnetized.

Massoud




--- news://freenews.netfront.net/ - complaints: news@netfront.net ---

 

[Phil Allison]

et...@whidbey.com wrote:

A motor was described to me today that looks like the typical shaded
pole motor that used to be found in old phonographs. It just has one
winding with only two wires. But the rotor is strongly magnetized. I
don't know if there is the shorted winding typical of shaded pole
motors. The motor is a pump motor in a washing machine and so it
presumably needs to turn the same direction all the time.

** Modern washer pump motors are real odd balls - see pic:

http://i01.i.aliimg.com/img/pb/524/202/238/1269049485101_hz_myalibaba_web2_1250.JPG

It's basically an induction motor with a permanent magnet rotor. The rotor is inside a water proof housing ( black plastic in this pic) and drives an impellor pump via a rubber belt.

This construction means the winding is completely external and safe from water.

Due to inherent asymmetry, they vibrate a fair bit too.


.... Phil

 

On Monday, December 7, 2015 at 3:42:26 PM UTC-8, et...@whidbey.com wrote:

A motor was described to me today that looks like the typical shaded
pole motor that used to be found in old phonographs. It just has one
winding with only two wires. But the rotor is strongly magnetized. I
don't know if there is the shorted winding typical of shaded pole
motors. The motor is a pump motor in a washing machine and so it
presumably needs to turn the same direction all the time.
Thanks,
Eric

Have one like that in our Kitchen-Aid (Whirlpool) dishwasher. I believe it runs whatever direction it starts in. The impeller is symmetrical so that doesn't matter. On ours the brass insert in the impeller came loose on the shaft. Fortunately it was under an extended warranty. Depending on vendor the price ran $35-$70, some made in USA and others China. (didn't have to pay it, just checked part number) BTW that permanent magnet is very powerful.

G˛

 

[default]

On Thu, 10 Dec 2015 22:20:39 +0000 (UTC), Massoud <mass110@yahoo.com>
wrote:

etpm@whidbey.com wrote in news:v66c6bdanki35n8prhbvbn7g0tlpvobqam@4ax.com:

A motor was described to me today that looks like the typical shaded
pole motor that used to be found in old phonographs. It just has one
winding with only two wires. But the rotor is strongly magnetized. I
don't know if there is the shorted winding typical of shaded pole
motors. The motor is a pump motor in a washing machine and so it
presumably needs to turn the same direction all the time.
Thanks,
Eric

That single loop copper wire generates magnetic phase shift for rotation.
The rotor should not be magnetized.

Massoud

I had a record turntable that had a motor like that. The motor was
synchronous and there was a shading pole to start it turning, and in
the right direction. I think that was my old Empire Scientific
turntable - the motor was in a perforated shielded cage and ran very
hot.

 

[default]

On Mon, 07 Dec 2015 15:44:22 -0800, etpm@whidbey.com wrote:

A motor was described to me today that looks like the typical shaded
pole motor that used to be found in old phonographs. It just has one
winding with only two wires. But the rotor is strongly magnetized. I
don't know if there is the shorted winding typical of shaded pole
motors. The motor is a pump motor in a washing machine and so it
presumably needs to turn the same direction all the time.
Thanks,
Eric

Seems there's a lot of confusion here. Is it the motor rotor that is
magnetized, or does an induction rotor drive a magnet?

In many pumps (these days) the motor will turn a magnet which in turn
will turn the pump impeller in a separate (non-magnetic) housing by
pulling the impeller along with the spinning magnet. It does away
with shaft seals in a direct coupling that will leak after a time.

An extension of the old laboratory magnetic stirrer: a "stir plate"
has a motor driven magnet and in the beaker/flask/whatever a Teflon
coated "stir bar" follows the magnet around.

 

On Mon, 07 Dec 2015 15:44:22 -0800, etpm@whidbey.com wrote:

A motor was described to me today that looks like the typical shaded
pole motor that used to be found in old phonographs. It just has one
winding with only two wires. But the rotor is strongly magnetized. I
don't know if there is the shorted winding typical of shaded pole
motors. The motor is a pump motor in a washing machine and so it
presumably needs to turn the same direction all the time.
Thanks,
Eric

Thanks All for your answers. I thought that shaded pole motors could
not have a permanently magnetized rotor and I thought that synchronous
motors needed at least two external power source energized windings to
get them to start rotation in a given direction. But as it turns out a
synchronous can be a shaded pole type. And it was the answers I got
here that led me to that conclusion. But I should have come to the
correct conclusion without help. That's because the shorted winding in
a shaded pole motor is still a winding. And even though it is not
connected to any external power source like the other winding is it is
still energized the same way a standard shaded pole is and it has the
same function.
Thanks,
Eric

 

[Cydrome Leader]

default <default@defaulter.net> wrote:

On Thu, 10 Dec 2015 22:20:39 +0000 (UTC), Massoud <mass110@yahoo.com
wrote:

etpm@whidbey.com wrote in news:v66c6bdanki35n8prhbvbn7g0tlpvobqam@4ax.com:

A motor was described to me today that looks like the typical shaded
pole motor that used to be found in old phonographs. It just has one
winding with only two wires. But the rotor is strongly magnetized. I
don't know if there is the shorted winding typical of shaded pole
motors. The motor is a pump motor in a washing machine and so it
presumably needs to turn the same direction all the time.
Thanks,
Eric

That single loop copper wire generates magnetic phase shift for rotation.
The rotor should not be magnetized.

Massoud

I had a record turntable that had a motor like that. The motor was
synchronous and there was a shading pole to start it turning, and in
the right direction. I think that was my old Empire Scientific
turntable - the motor was in a perforated shielded cage and ran very
hot.

Got a Dual turntable motor at my desk that's a hybrid like that. It looks
like a plain (but overly built) shaded pole motor but with two windings-
one on each side of the rotor. It also has a segmented permanent magnet
mounted on the cast Al cage/rotor that I guess makes is run sync after
speeding up. There is a spider shaped set of poles surrounding the
permanent magnet part. Never seen a motor like this before, but I also
don't deal with record players.

 

[wbeaty]

On Monday, December 7, 2015 at 3:42:26 PM UTC-8, et...@whidbey.com wrote:
> But the rotor is strongly magnetized. I don't know if there is the shorted

The magnetization might be irrelevant.

Usually induction motors are made of transformer-steel, which acts like soft iron and won't preserve much magnetization.

Also, any magnetization of the rotor is always getting wiped out by the "slippage" as the rotor moves slower than an exact fraction of 60Hz (so not 1800RPM, but 1750 or something.) The strongest part of the rotating magnetic field is always sweeping slowly along the rotor, and not staying in one place.

But perhaps if the motor was turned off extremely suddenly, then it might stay measurably magnetized?

Or maybe they made the rotor out of standard steel laminations, rather than transformer alloy. In that case it would become *extremely* magnetized. Probably it would draw an unusually large wattage, and the rotor get smoking hot during normal use. It's like an induction furnace heating up a steel frying pan.

The motor is a pump motor in a washing machine and so it
presumably needs to turn the same direction all the time.

No capacitor? Or no centrifugal starter switch inside? If not, then the position of the pole-shading shorting rings will force it to only go CCW or CW.