How a AC motor can reverse rotation with wire flips?

AlexLPD

Joined Aug 22, 2010
60
Hi to you all!

When I was in highschool in the electricity shop tall us the rotation of an AC motor cant be reversed.
Today we gave mainance to an AC 110-220V motor and in the plate has the legend; for changue rotation changue black wire to blue.

Of course nothing to do with changing the color of the conductor. Just their position in the electrical joints.

Latter on we have to changue rotation.

And I'm guess whath is the theory behind this?

From the rotation part... I guess the 110-220 has to do with the resistance of windings .

Thanks.
-Alex.

#12

Joined Nov 30, 2010
18,223
AC motors always have an imbalance in their magnetic fields or they wouldn't know which way to turn. Moving a couple of wires moves the imbalance.

Joined Jul 18, 2013
25,469
When I was in highschool in the electricity shop tall us the rotation of an AC motor cant be reversed.
Today we gave mainance to an AC 110-220V motor and in the plate has the legend; for change rotation changue black wire to blue.
-Alex.
AC motor is a vague description, there are several technologies, but simplistically all that has to be done is change the relative polarity of a a field, whether induction, Universal, synchronous, split phase, 3 phase etc.
Max.

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AlexLPD

Joined Aug 22, 2010
60
So in resume...
All AC motor.can be reversed, and for doing that it is necessary to flip the pole of the start winding.

Concreatly in AC motor....
At changue the wires we are fisically changing the start pole? At the same phase?.

So lets say the ph1 is the start and goes to 9 o clock. By changing the wires... We are putting the PH1 to 3o clock for saying? (I now may be a little more close to impulse the cage)

Alex.

Joined Jul 18, 2013
25,469
In a 1ph induction motor a method is used to create an artificial phase (split phase) usually done using a second winding in series with a capacitor to shift the phase ~90°.
reversing either of the windings results in a motor reversal, or a relative phase angle change between the windings.
Max.

AlexLPD

Joined Aug 22, 2010
60
So... Can I reverse the polarity of this fans with the appropriated arduino sketch and the appropiatted circuit?

Maybe a pass by cero triacs and a squematic to allow the changue of the start?

These are 115V AC, capacitor start fan motors... they run on 0.2Amp

Excuse the trouble but... can share an schematic? .
They will not be changing the rotation very often, just a litte bit of a trick.

Thanks a lot.
-Alex

AlexLPD

Joined Aug 22, 2010
60
Well 5 min of free time;

http://lumberjocks.com/topics/48372
How to reverse turn on a sander.

Know I have to take a closer look to the motor, and see if have the leads prepared or need to be added from ouside.
I guess a simple 3 position switch will do the trick. And once it passed on the arduino control Tada... reversible
air flow on evap...

I know I know the Q inst gone be the same, and all... but for this particular application come handy dandy.

Thanks a lot!
This is a great place to learn stuff.

-Alex.

Joined Jul 18, 2013
25,469
You will either need to access both ends of both windings, or if as often the case with a small fan motor, the start and run windings may be identical, accurately measure the resistance should indicate it.
If so see the pic for the dashed alternate connection, this method uses the existing 3 wire connection and just swaps the winding for main and split phase. (run/start).
Max.

Max.

AlexLPD

Joined Aug 22, 2010
60
So... Can I reverse the polarity of this fans with the appropriated arduino sketch and the appropiatted circuit?

Maybe a pass by cero triacs and a squematic to allow the changue of the start?

Thanks a lot.
-Alex

#12

Joined Nov 30, 2010
18,223
In post #1 you said you can reverse the motors by moving a black wire and a blue wire.
We can not see the drawing on the motor from here.
Nobody can draw for you how to wire an Arduino without knowing WHERE to move the wires.

AlexLPD

Joined Aug 22, 2010
60
In post #1 you said you can reverse the motors by moving a black wire and a blue wire.
We can not see the drawing on the motor from here.
Nobody can draw for you how to wire an Arduino without knowing WHERE to move the wires.
Hi, yes! ... the wiring and the coding of the arduino will be no problem... Once I add the neccessary leads to the motors, the circuit is pretty easy, and control it by an arduino is also easy.

Thanks!
-Alex.