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Thread: Why does my Leeson Three phase motor have wiring instructions for reverse?

  1. #1
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    Why does my Leeson Three phase motor have wiring instructions for reverse?

    My Leeson three phase 7.5 Hp motor has instructions to wire it to run on high or low voltage. It also says to interchange some leads to reverse rotation. Not to just reverse any two input wires.
    Is there any reason not to just reverse it by switching the leads at the wall. Maybe some efficiency thing?
    Bill D

  2. #2
    I'd like to know this as well. When initially setting up a few of my machines, they ran backwards. I just reversed two input wires at the extension cord or at the wall to change the direction.

  3. #3
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    I think it's so all ther motors that might get plugged onto the same outlet run the same direction. '
    The Plane Anarchist

  4. #4
    Quote Originally Posted by Bill Dufour View Post
    My Leeson three phase 7.5 Hp motor has instructions to wire it to run on high or low voltage. It also says to interchange some leads to reverse rotation. Not to just reverse any two input wires.
    Is there any reason not to just reverse it by switching the leads at the wall. Maybe some efficiency thing?
    Bill D
    No efficiency gains; resistance is resistance in either direction. Switching at the wall is easiest for 1 motor, but many industrial motor arrays are powered from the same distribution bus/feeder/starter. It might be tough to do a 2-wire swap (reverse) on the bus, or feeder, or even common starter, just to get one motor right, and not screw up 6 others.

  5. #5
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    I've seen machines that run in forward and reverse. If I'm not mistaken, Woodmaster has a drum sander that will run forward and then you can push a button and the material will run back the opposite direction so you can sand again. This keeps you from handling material that is long and heavy. I've watch several videos of these types of machines. This may be the reason you see this on the tag. All it takes is a switch to reverse the phase in the wiring to do this.
    My Dad always told me "Can't Never Could".

    SWE

  6. #6
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    My woodmaster drum sander just uses a dc motor for the feed and a simple reversing switch. No three phase on it.
    The Plane Anarchist

  7. #7
    3 phase motors can be ran forward or reverse in use, say a conveyor line. That is why they make reversing magnetic motor starters.

  8. #8
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    Quote Originally Posted by Darrell Bade View Post
    3 phase motors can be ran forward or reverse in use, say a conveyor line. That is why they make reversing magnetic motor starters.
    I though those just reversed two leads going towards the motor. Not any wiring inside the motor box itself. That is how my lathe did it.
    Bill D

  9. #9
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    DPDT a drum switch is an effective and affordable solution for reversing electric motors. I had electric power on the MerryTiller for a few years, reverse was a great feature. I could only till when Larry and Curly were over. The tiller motor is now on my buff, reverse is surprisingly helpful.

    IMG_0554.jpg Screen Shot 2022-05-25 at 7.48.36 AM.png
    Last edited by Maurice Mcmurry; 05-25-2022 at 8:55 AM.
    Best Regards, Maurice

  10. #10
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    Quote Originally Posted by Bill Dufour View Post
    I though those just reversed two leads going towards the motor. Not any wiring inside the motor box itself. That is how my lathe did it.
    Bill D
    You are correct Bill.

    I believe the OP’s motor had reversing instructions because the manufacturer decided to provide them, odd with 3 phase motors…..Regards, Rod

  11. #11
    Quote Originally Posted by Maurice Mcmurry View Post
    DPDT a drum switch is an effective and affordable solution for reversing electric motors. I had electric power on the MerryTiller for a few years, reverse was a great feature. I could only till when Larry and Curly were over. The tiller motor is now on my buff, reverse is surprisingly helpful.

    IMG_0554.jpg Screen Shot 2022-05-25 at 7.48.36 AM.png
    It's your shop and your body, but that uncovered belt and pully would scare me. It's so easy to get a piece of clothing caught in something like that.

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