# rotatig magnetic field

• posted

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...

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• posted

How about someone flying to meet you to explain in person? What have you done so far to find out for yourself?

Bill

• posted

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.

• posted

| 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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