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Reversing rotation on split-phase motor?

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francist

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#1
We seem to have had a run on electric motor questions lately, any chance there's room for one more?

I've got a 1960's vintage Leland "KS" series 1/3 HP motor. Runs fine, just the opposite rotation to what I need so I'm wanting to switch the direction. I dug up an old Leland catalogue sheet and according to it this is a split-phase induction motor that should be electrically reversible. I'm just not sure how to go about it so I'm hoping some of you guys can help me out.

There's no start nor run capacitor involved, and it has a centrifugal switch to disconnect the start winding once it's wound up. Only three lug terminals accessible under the cover not including the chassis ground. Here's a photo. The terminal posts are not numbered on the actual motor, but I have given them numbers 1-2-3 on the photo so we know what we're talking about. The motor presently runs CCW with 110 VAC connected to posts 2 and 3.

image.png

When I disconnect both Red wires coming from inside the motor (as well as the AC leads) and measure across the terminals, I have continuity between all three terminal posts. There is no continuity from any of the terminals to chassis. There is also no continuity from any of the terminals to either of the Red wires, but there is continuity through the two ends of the Red wire itself. Resistances are as follows:
1 to 2 = 1.5 ohms
1 to 3 = 0.2 ohms
2 to 3 = 1.5 ohms
Red to Red = 2.5 ohms

From the above, I infer that the two Red wires are the start winding, and the run winding is 1-2 or 2-3. I'm thinking it can't be as easy as just interchanging positions the positions of the two Reds, so any ideas on what I need to do?

-frank
 

markba633csi

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#3
Try interchanging the two reds. Alternately, try applying power to 1 and 2 instead of 2 and 3
mark
 

Cooter Brown

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#4
Some single phase motors are not reversible..... You can try changing the connecting like you are thinking, you can't hurt the motor if you get it wrong, just make sure to label everything...
 

RJSakowski

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#5
Reversing a single phase motor requires reversing the leads on either the start or run windings. If one of the leads from a winding is internally tied to a lead from the other winding, the motor would not normally be reversible.
I have opened a motor up and found the internal connection, broke it and brought the separate leads out so I could reverse the motor. It is kind of iffy as sometimes the connection is not that easy to access but if the motor is not usable otherwise, it's worth a try.
 

francist

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#6
Try interchanging the two reds. Alternately, try applying power to 1 and 2 instead of 2 and 3
mark
Yes, this worked! Interchanging the positions of the two red wires, motor now runs in the direction I want. Arguably the most self-evident solution right from the get-go, I had convinced myself that it was just too easy to be true. I'm not the best when it comes to sussing the electrical stuff -- thanks Mark!

Thanks everybody, situation is remedied.

-frank
 

markba633csi

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#7
Good deal Frank!
M
 
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