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Joined: Jan 2021
Posts: 3
M
MCosta Offline OP
New Member
Hi everyone,
I am a mechanic with some basic electrical background knowledge but not enough for this small project.

I have just acquired a new three phase motor without capacitor. It has four wires going into the windings, black, red, blue and yellow.

To this motor I need to connect a forward/reverse switch with off position in the middle.

My question is of course, how do I go about doing this? Some easy to follow basic instructions would be very much appreciated.

Joined: Jul 2004
Posts: 9,677
Likes: 9
G
Member
What does the wiring diagram look like on the motor? Typically swapping any 2 phases reverses the motor but you need to identify which of those wires are phases. I suppose it is possible that this is some sort of wye winding (I have never seen it) and the blue is the neutral but I would not start hooking up wires randomly without knowing for sure what you are looking at. When in doubt, drop it on the counter at a motor shop and have them take a look.


Greg Fretwell
Joined: Jan 2021
Posts: 3
M
MCosta Offline OP
New Member
Hey, thanks for taking the time to help!
Much appreciated.
I should have mentioned that on this motor one swaps the red wire with the black to reverse rotation. And then there are the two line connections of course, L1-L2.
My problem is not knowing how to do the forward/reverse switch connections.

Joined: Jul 2004
Posts: 9,677
Likes: 9
G
Member
Let's make sure we are on the same page here. Ph A and Ph B are what you call L1 & L2 and you connect either red or black to Ph C to swap direction? The other stays unconnected? That sounds strange to me for a 3p motor but if that is how it works, you need a single pole double throw switch. Connect the Ph3 to the common and red and black to the other 2. That is just direction control, you still need a disconnect.


Greg Fretwell
Joined: Jan 2021
Posts: 3
M
MCosta Offline OP
New Member
Hi there again.
Here are some pics of the motor wiring. I hope they help.
As you know, when one swaps the red wire with the black manually, we reverse the rotation. But how the heck does one control that with a switch?

Thanks again for your time smile


https://photos.app.goo.gl/Hbxbrz9mK5jai3Sw5
https://photos.app.goo.gl/5zUH1V6H4JMM3xeQA
https://photos.app.goo.gl/eDuE96n6829D4zY77

Joined: Jul 2004
Posts: 9,677
Likes: 9
G
Member
Why do you think that is a 3 phase motor? It looks like a garden variety six wire single phase motor to me.
I bet there is a capacitor there somewhere.
At any rate you need a double pole double throw switch. They do make them that sit in a plastic bubble that replaces the wiring cover. If you can come up with a way to mount a "4 way" switch like a handy box connected to the threaded hub where the power comes in with a close nipple and feed the power cord through, you would extend the red and black into the box and hook them to one side of the switch, Bring out the other side to the terminal block. What they call a "4 way" is simply a reversing switch, typically used for "3 way" lighting circuits. Just be sure you buy one that will handle a motor load. (20a spec grade should do it)
Something like this

https://www.homedepot.com/p/Leviton...UgzoEAQYBCABEgLlufD_BwE&gclsrc=aw.ds


Greg Fretwell
Joined: Nov 2005
Posts: 826
J
Member
https://www.digikey.com/en/products/detail/nkk-switches/S43F/1007002
Welcome to ECN!
I believe that you would want to use a properly rated, 4PDT, Center Off, toggle switch. That's because you shouldn't leave one winding energized, when the motor isn't running. Wire the four motor leads to the middle poles, which we'll call "c". We'll call the 4 switch sections 1 through 4, and the 2 throws, "a" and "b".
Motor first:
1c to Black
2c to Red
3c to Yellow
4c to Blue

Cross Connects:
1a to 2b
2a to 1b
3a to 3b
4a to 4b

Power:
L1 to 1a and 3a
L2 to 2a and 4a

Hope this helps
Joe4


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