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Topic: its possible to change dir in an AC motor (Read 1 time) previous topic - next topic

copachino

hi, yestarday i was wondering if its possible to change the spin of an AC common motor, for example if its run in CW change that for CCW without modifying the motor itself, maybe some kind of inverter??

Grumpy_Mike

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its possible to change the spin of an AC common motor,

What sort of AC motor?
Normally this is not possible.

retrolefty


hi, yestarday i was wondering if its possible to change the spin of an AC common motor, for example if its run in CW change that for CCW without modifying the motor itself, maybe some kind of inverter??


Typical not unless the AC motor is designed for bidirectional service, for capacitor start motors this isusually done by selecting proper motor starting capacitor leads Vs field winding leads choice. So with proper relay selected connections wired up to a proper AC motor type it is possible.


http://i40.tinypic.com/vh6qo0.jpg

Lefty

copachino

i was wondering because some guys once put a fan motor for an elevator project(small project) and they change the spin dir with just a switch, but the motor was not designed to go in CCW...


shayrgob

Please correct me if I'm wrong but isn't it simply a matter of inversing polarity?

copachino

that what i thought but, how can u change the polarity???, the only thing tha came to my mind its something like a opamp.... but maybe there is a simple way to do it

Grumpy_Mike

It is AC, it doesn't have a polarity!

With AC first one wire is positive and the other is negative, the in a 60th of a second (or so ) this is reversed. The change over from one state to the next is normally a smooth sinusoid.

zoomkat

120vac box window fans have bidirection and speed setting capabilitys, so a google search might produce working info.
Google forum search: Use Google Advanced Search and use Http://forum.arduino.cc/index in the "site or domain:" box.

copachino


It is AC, it doesn't have a polarity!

With AC first one wire is positive and the other is negative, the in a 60th of a second (or so ) this is reversed. The change over from one state to the next is normally a smooth sinusoid.


yes it doesnt have polarity but.... i have made i small experiment, i just put upside-down the stator and as spected the motor changes from CW to CCW.... so, may be a posible way to change dir externaly or that what i think...

Grumpy_Mike

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yes it doesnt have polarity

No it doesn't, what makes you think it does!!!
Live and return are not polarities.

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i just put upside-down the stator and as spected the motor changes from CW to CCW

That means you have a motor like retrolefty talked about, that is why I asked you what sort of motor you had in the first reply.

copachino

as i say the motor only has two pins for 110V nothing else, also its marked as CW.

jeffmorris

I know that Lionel O-Gauge trains which run on AC instead of DC have a device that changes direction of the motor. Some AC motors can be rewired to change directions or voltages.

I  have an ac motor that controls the up - down motion of the platform for a Treadmill, exercise machine.  It uses a pair of triacs to control each direction.  The front triac is an opto-isolator and that controls a gated triac for the 120 v windings.  The motor has 3 leads: common, cw and ccw.  Of course, this is a special type of ac motor designed to run bi-directional.

Pj

Grumpy_Mike

What does this mean
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i just put upside-down the stator and as spected the motor changes from CW to CCW

If yo are physically reconfiguring the motor then you can not do this electronically without having another coil.

jackrae

If you managed to "simply" reverse the stator (mechanically) then I suggest you have a shaded pole motor, the direction of rotation being influenced by the "side" that the shaded pole is on, with respect to the rotor core.  A photograph of the motor would end 99% of the speculation since your original question mentioned an "AC common motor", whatever one of those.

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