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rudimentary ac and motor winding question
3

rudimentary ac and motor winding question

rudimentary ac and motor winding question

(OP)
Sorry for the 'youshouldknowthis'aspect of this question, but quickly.......a coil of wire will generate a magnetic field when current passes through it.  In the case of a stator winding, the current goes through the wire in one direction, creating a magnetic field perpendicular to it, causing the rotor to turn one direction.  as the current then changes direction, you would expect the magnetic field to change with it.  I know there is a time factor here, field collapsing time, etc.. so is such that as the the direction of the current changes, that it is changed back so quickly that the back emf sort of maintains the existing direction until the opposing direction has switched back to the initial direction?  

More simply put, how does a current changing directions 120 times a second cause a magnetic field to remain in only one state?  How does it choose which direction?  Why would one direction overcome the other?  

Does this make sense?   

RE: rudimentary ac and motor winding question

Seems like there is too much of your explanation buried in your question to figure out what your question is.
What is the question?
What type of motor?
 

=====================================
(2B)+(2B)'  ?

RE: rudimentary ac and motor winding question

(OP)
sorry.  any ac motor. how does the change in direction of the current maintain a resulting single direction of the rotor?

RE: rudimentary ac and motor winding question

It's obvious you want to learn more about electric motors.

Please note Eng-Tips is for engineers helping one another, it is not intended to replace your ability to research electric motors via Google/Wikipedia/etc. or to take a university class.

RE: rudimentary ac and motor winding question

For a three-phase motor, there is a rotating magnetic field that "pulls" the rotor around.  

For single-phase motors, there is an oscillating magnetic field that will pull the rotor around - once you get it moving in one direction or the other.  

Wikipedia for more..  

 

David Castor
www.cvoes.com

RE: rudimentary ac and motor winding question

2

Quote:

how does a current changing directions 120 times a second cause a magnetic field to remain in only one state?

The magnetci field doesn't stay in one state. The magnetic field obeys the laws of physics in a motor.

http://www.lmgtfy.com/?q=ac+motor+theory

Try the first link to start...

RE: rudimentary ac and motor winding question

Lionel, a star fot the lmgtfy link.  It will come in so handy!!

Good on ya,

Goober Dave

RE: rudimentary ac and motor winding question

(OP)
sorry for the stupidity, a question was posed to me that got me thinking and I had a block....that google link is cool though.  I'm sure we all know someone we want to make feel stupid.. :)  I did search for the answer prior to posting and my skimming articles didn't fully answer my question - figured you guys would give me the quick answer, and the engineer anality was expected...thanks though...

RE: rudimentary ac and motor winding question

Well, I didn't red flag it because you have been here for a while. But still, a few Google searches should have found something and, considering the nature of these forums, explaining basic AC motor theory should not be required here.

Maybe I just got lucky picking better search words. "AC motor theory" was my first search attempt. I didn't keep trying search terms until I got a good search result.

RE: rudimentary ac and motor winding question

(OP)
I appreciate your patience Lionel. I try not to ask such silly questions, but they slip out sometimes.  I don't remember which search terms i used.  Thanks again...

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