SIngle phase ac motor question

Ok I think I have it. You don't need a rotating magnetic field at all is the point. If it goes N-S then S-N at the right time then it acts as a single phase induction motor.

I've been looking at lots of Youtube videos of people trying to make permanent magnet motors. To me this is impossible since both fields are fixed. By permanent magnet motors here I mean motors that have fixed magnets on the rotor and stator but with no power source! I assume they must all be frauds as such a motor would align the rotor after a few turns and stop.

Hardy

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Phil, Thanks for the link. I still think that induction motors are magical devices. Which means I kinda understand them, but not really.

George Herold

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John, Sign me up for a copy of the book! I'm going to need lots of pictures if I'm going to understand induction motors.

George Herold

Are you going to put that in the blurb on the book's cover jacket? :)

Seriously, go for it, I will look forward to buying it.

I think I'll just post it to the web. Official publishing sounds like too much hassle.

John

Is that why you reply to dimbulb?

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Larkin can't write a book. He'll make a gross error in Chapter 1, then spend the rest of the book proving that he's right even when he's wrong ;-)

...Jim Thompson

I would have to say you are right. _However_, i have yet to find a single phase induction motor that did not in some way create a rotating field component in any (combination?) of several different ways.

Capacitor run motors, Capacitor start motors, Low R winding with high R winding, Shaded pole types, probably more. .

I think you are going to have to go to sci.physics for the answer. ISTR that when the rotor is moving it "retards" the field somehow but i can't do the physics any more. .

The rotor tries to follow the 60hz AC wave around the coil, which is on the outside. The starting windings are offset, so when they are active 2 fields are active and out of sync somewhat, giving enough startup torque to break the friction and start the rotor. The rotor never catches the magnetic field of course, due to friction, but if it did, the motor would stop.

If I recalled this correctly. I learned this 30 years ago in high school electrical class. I remember we figured out how fast the unloaded motors where supposed to go, and it was 1800 RPM, but the real speed was 1725 due to friction loss.

- Tim -

Jerk.

John

Slow to catch up this week-end ?:-)

But doesn't my comment fit? You're forever throwing s*it against the wall. When it doesn't stick (schtick ?:-), you go into a defense tirade.

Grow up! Pathetic!

...Jim Thompson

Well, the two younger guys I was skiing with me couldn't keep up... by about a factor of three. I got to enjoy a lot of scenery.

But it's just as well it's raining this morning. I did a yard sale yesterday at about 45 mph - one of my skis was about 50 yards up the hill - and it feels sort of like the day after a car crash. A young girl brought down my gear - 2 skis, 2 poles, one glove - and picked me up, and I offered to marry her.

For someone who makes the same tired political comments all the time, and contributes mostly nothing on-topic... it's stupid to criticise me for being usually right. And I'm usually right because I'm usually careful, as any engineer should be.

Your resistor noise question was interesting. Senility is partly voluntary, you know.

John

Self-publishing, then?

I think you will write more than one book. Just a hunch. ;-)

Let us know when your first work is available

Ah yes, jerk... d^3 s / dt^2 ? ;-)

Michael

And what is braggadocio ?:-)

...Jim Thompson

=A0 =A0 =A0...Jim Thompson

What did she say to that? ;-)

In the eye of the beholder.

John

Looks to me like it's in the eye of the braggart. "Well, the two younger guys I was skiing with me couldn't keep up..." Bwahahahahahaha ;-)

...Jim Thompson

Hey, align yourself with the doofusses and old farts if that makes you comfortable.

John