Another AC Motor Question. This One Is A 3 Speed

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Old 08-16-09, 10:24 PM
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Another AC Motor Question. This One Is A 3 Speed

I have an AO Smith AC motor, 3 speeds according to the tag. About 800, 950 and 1125 RPM. Problem is, no matter which leads I hook up to the power, it only runs at one speed (which one , I don't know). Here is the wiring diagram from the motor.





I was trying to get low and high and here is how I wired it:







I don't know diddly squat about AC motors, so I am wondering if there is a switch wiring schematic that is missing from the motor. Or maybe they never worked right in the first place, and that is why I got "such a deal" from the surplus store.
 
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Old 08-17-09, 04:24 AM
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That looks like it should work ok.
do you have any load on it, it may need some load in order to show you a difference in speeds.
You have the capacitor in there right ?
 
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Old 08-17-09, 09:31 PM
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I have the capacitor in place, as specified by the motor tag. As far as load goes, I believe there is very little as I have geared the motor down to a final drive of 60 RPM, and all that is turning between the rollers is a 2 pound canister.


Ball mill, still in "beta" stage:



 
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Old 08-18-09, 04:56 AM
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Try taking the switch out of play and wire the low or high speed direct. Then let us know.
Jim
 
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Old 08-19-09, 09:41 AM
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I wired it direct but I am still not seeing any difference.
 
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Old 08-19-09, 10:46 AM
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this is more of a question than an answer.
wouldn`t you have to variate the power for the high and low?
if you put the same into the motor it would run at the same speed. i think that the high speed circuit is for higher in-put and it`s wired for such. like 110 volts to 120 volts.

maybe a reistatic switch ( variable speed control) would be the answer.
wire the power to that then to the motor and control it from that.like for the dimmer on a light switch. but once again under power and over power can make it burn out.i`d try this and do a quick test and monitor the heat and go a little longer each time if it works. i`m not an electrical engeneer by any means ( not even close). may be some one else can approve or disapprove this idea here.

i have a mechanical variable speed pully that would work.
v-belt of course. then you`d need a mechanical tensioner.
and you`d have to re-pully the whole thing. i just looked back at the pic. so that may be out.
 
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Old 08-19-09, 10:58 AM
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Printerman..the speed of the motor depends on the internal windings, just like a multi speed motor in an air handler for a furnace-A/C system.

buns...is the motor used? Maybe its just no good? Also, those speeds are pretty close together...are you sure its NOT running correctly?

btw kind of a cool setup..but whats it really for? Almost looks like a rock tumbler or something.
 
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Old 08-19-09, 12:22 PM
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real good gunguy45
like i said i`m not too much into motors and how they work exactly.
all the motors i use have speed controls seperate, like the reostat. ( sounds like re-o stat).
all the speed controls are in a control box.
 
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Old 08-19-09, 04:37 PM
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Have you actually tried to count the revolutions per minute? 800 is about 72% of 1125 and even with the double reduction drive I don't think that it would be immediately apparent that a speed change had taken place by visual inspection only.
 
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Old 08-19-09, 04:51 PM
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durn I meant to add that without a strobotach or one those shaft tach type things..there really wouldn't be a way to tell the exact speed.
 
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Old 08-19-09, 07:39 PM
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Originally Posted by Gunguy45 View Post

buns...is the motor used? Maybe its just no good? Also, those speeds are pretty close together...are you sure its NOT running correctly?

btw kind of a cool setup..but whats it really for? Almost looks like a rock tumbler or something.

I bought the motor from a surplus store. It looked new, but even so, there was no gaurantee that it worked.

The machine is used to keep my mettalic ceramic header coatings mixed. They are kind of like oil and vinegar dressing. As soon as you stop shaking, the solids sink to the bottom.




Originally Posted by furd View Post
Have you actually tried to count the revolutions per minute? 800 is about 72% of 1125 and even with the double reduction drive I don't think that it would be immediately apparent that a speed change had taken place by visual inspection only.
Yes, your right. Even if the motor was spinning 200 RPM faster, the roller would only turn about 10 RPM faster. That wouldn't help much at all. Thanks for all your replies.
 
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