2 Speed Fan Motor Question -- No Diagram

[Waterlooboy2hp]

I picked up a 1/5th , double shaft fan motor to use on a project. On the tag, it lists it as 1600/1200 RPM. It uses a 10 mfd capacitor, which I already had. There are only 4 leads. 2 shorter ones, that are taped side by side, and 2 longer ones that are also taped side by side.

One pair appear to come from a set of field windings, wound with smaller gage wire. The other pair look to come from a set of field windings, that are wound with heavier gage wire. I could not figure out how they got 2 speeds from the motor. I only need the 1200 rpm speed.

A thought hit me the other night, that maybe one pair clip to the capacitor, and 115 vac feeds the other pair for 1 speed. Then, you reverse the hook-up to get the 2 speed. (all 4 leads have connectors on them). Does that make sense?? I just don`t want to use the "Tune for minimum smoke" method on this one. --- John

 

[Alan Douglas]

Doesn't seem likely. The heavier winding should be energized all the time, and normally the other winding would be fed through the capacitor. How they get the lower speed I don't know. I doubt if it's very well regulated, and I wouldn't expect to get 1/5HP at that speed either.

 

[UncleRuss]

Pretty straight forward my friend. Two speed, two windings, four wires. These split phase fractional horsepower motors are generally pretty smoke proof. You have to get the direction of rotation right when you purchase them as they are non reversible except by turning the whole motor end for end. There is no starting winding, you just put the leads across the line and the cap gets them going and helps regulate constant speed. These motors have a very high impedance so utilize this for overload protection and unless physically damaged very seldom burn out. Now get the air moving!

 

[Waterlooboy2hp]

Doesn't seem likely. The heavier winding should be energized all the time, and normally the other winding would be fed through the capacitor. How they get the lower speed I don't know. I doubt if it's very well regulated, and I wouldn't expect to get 1/5HP at that speed either.

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All`s well that ends well. I recalled an "Old School", 2 man motor repair shop in my area. I say Old School. because it has been there since god was an altar boy.

The owner was stumped a bit at first. He ran several wire combinations by me, but each time, he concluded that they were not right. Then he grabbed a piece of cardboard and drew a diagram for me. Said, this is what I think it should be, but I am not 100% sure. I wired it up this morning, and the man was Spot-On with his diagram. Here is the wire combo --

Brown to 10mf capacitor --- White to other side of Capacitor and on to L2 --- Black is Hi L1 --- Orange is Low L1 . Motor even turns in the right direction for how I want to mount it for my project.
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I want to be sure that the 10mf x 250 volt capacitor is the right type. I know it covers the number specs, but it came from a very tiny motor in a portable humidifier. Is there a better style of capacitor for this 1/5hp motor?? - John

 

[Ulma Doctor]

Sweet! Nice to hear you got it handled!!
I'm assuming it's a polyfilm cap....
in that capacity for a 1/5 hp polyfilm caps are fine.
if you want to overkill for service longevity, use a 10uf 250v oil filled capacitor- totally unnecessary but it would most likely last forever.
the cap in the video is an oil filled capacitor

 

[Wireaddict]

Some thoughts about the cap you're using: 10 uF [microfarads] sounds a bit small but if it runs the motor OK it's probably adequate. The other thing: you didn't say but I assume that your 10 uF cap is rated at 250 volts AC, not DC or it would've failed by now.