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tonyr417 10-25-2010 09:15 PM

Wiring Single Phase through 3 Phase socket
 
I have a woodworking machine that has a single phase motor. The machine has a socket mounted on its side so that a power feeder can be mounted and plugged in. However, for reasons that probably relate to ease of manufacturing (this particular machine is often manufactured with a 3 phase motor), that socket is a 3 phase socket, and when I open it up is fully wired for 3 phase (earth, neutral, L1, L2, L3). Also, the machine is used in my basement and I am 99.9% sure that I don't even have 3 phase power in my home.

My power feeder, which is single phase, has the standard 3 wire configuration, one ground and 2 hot (I believe its 2 hot, or is it 1 hot and 1 neutral? Colors are green/yellow, brown and blue).

How should I wire the power feeder into the mating side of the 3 phase receptical so that it will work correctly? Can I just wire the ground to earth and then wire the 2 hot wires into L1, L2 and L3 until a combination gets the feeder to work? Is there any risk in this procedure to either me or the machine(s)? Is it even possible to wire the unit given this situation?

Thanks for advice.

Tony.

nap 10-25-2010 09:43 PM

where in the world is tonyr417? the answers you need can be different depending on where you are.

joed 10-25-2010 10:25 PM

The manufacturer should have a wiring diagram for the machine. I would not guess. If you can't get a drawing then open the machine up and investigate how it is internally wired.

dmxtothemax 10-26-2010 12:29 AM

A three phase motor will not run correcttly on a single phase supply,
If you are sure its a three phase motor, then you will have to get a
three phase supply, or change the motor over to a single phase motor.

Quote:

Originally Posted by tonyr417 (Post 522976)
I have a woodworking machine that has a single phase motor. The machine has a socket mounted on its side so that a power feeder can be mounted and plugged in. However, for reasons that probably relate to ease of manufacturing (this particular machine is often manufactured with a 3 phase motor), that socket is a 3 phase socket, and when I open it up is fully wired for 3 phase (earth, neutral, L1, L2, L3). Also, the machine is used in my basement and I am 99.9% sure that I don't even have 3 phase power in my home.

My power feeder, which is single phase, has the standard 3 wire configuration, one ground and 2 hot (I believe its 2 hot, or is it 1 hot and 1 neutral? Colors are green/yellow, brown and blue).

How should I wire the power feeder into the mating side of the 3 phase receptical so that it will work correctly? Can I just wire the ground to earth and then wire the 2 hot wires into L1, L2 and L3 until a combination gets the feeder to work? Is there any risk in this procedure to either me or the machine(s)? Is it even possible to wire the unit given this situation?

Thanks for advice.

Tony.


tonyr417 10-26-2010 05:22 AM

I am located in westchester, NY.

To be clear, the woodworking machine is single phase, the home is single phase and the feeder is single phase.

The receptacle is a 3 phase socket wired with all 5 wires -- a manufacturing error.

The machine is large and complex, no way to open it up and follow the wiring. Is there a way I can test the socket to see which prongs are wired as hot and neutral? And then is there a way to confirm that the so-called neutral is in fact a grounded conductor?

Many thanks, tony.

a7ecorsair 10-26-2010 08:35 AM

Quote:

Originally Posted by tonyr417 (Post 523112)
I am located in westchester, NY.

To be clear, the woodworking machine is single phase, the home is single phase and the feeder is single phase.

The receptacle is a 3 phase socket wired with all 5 wires -- a manufacturing error.

The machine is large and complex, no way to open it up and follow the wiring. Is there a way I can test the socket to see which prongs are wired as hot and neutral? And then is there a way to confirm that the so-called neutral is in fact a grounded conductor?

Many thanks, tony.

It's large and complex? It could very well have a single phase motor but if it is complex, you will have to determine if the other phase legs are used to power other sections of the machine. Apparently you've found the motor tag, what size motor is it? What other electronics are in this machine?

joed 10-26-2010 08:52 AM

The only prong you can confirm is the ground. Measure from that prong to any metal part of the machine.
I would suggest you need to contact the machine's manufacturer. They don't usually make "mistakes" on the type of plug they install.

How about providing some details on exactly what the machine is. Make? Model? What does the name plate on the machine say as a power input? Did you open any of the panels? Some machines provide wiring diagrams glued to inside panels or in pockets located in the wiring box.

Edit:

I see you are refeing to the socket for a power feeder to ADD to the machine and not the actual plug. Does the machine currently operate? If it does then you could measure the voltages on the plug for the power feeder as the machine is running. It could be that the power feeder is speed controlled and the plug has nothing to do with 3 phase power. It could just be speed control functions. Give us more details on this machine.

nap 10-26-2010 10:26 AM

just a heads up everybody. The color scheme tony has given is a european color scheme.





Quote:

The machine is large and complex, no way to open it up and follow the wiring.
I suggest you obtain a schematic of the machine. If there is an error in wiring, then you have no idea what is connected to what. There could be connections that are not intended. You would need to be able to verify any wiring in place even to know if it can be used as is without rewiring some part of the machine.

Not being mean but, to me, this sounds like you need somebody that has a more thorough understanding of electrical systems do some hands on investigation of the situation.

mpoulton 10-26-2010 12:44 PM

Quote:

Originally Posted by tonyr417 (Post 522976)
How should I wire the power feeder into the mating side of the 3 phase receptical so that it will work correctly? Can I just wire the ground to earth and then wire the 2 hot wires into L1, L2 and L3 until a combination gets the feeder to work? Is there any risk in this procedure to either me or the machine(s)? Is it even possible to wire the unit given this situation?

This sounds simple to me. Turn the machine on and operate it so that the power feeder would be running if it were attached. Measure voltage between the L1, L2, and L3 terminals in the receptacle. One pair of terminals should have 240V between them (or whatever your line-to-line voltage is). It will be L1-L2, or L2-L3, or L1-L3. Wire the motor to those terminals and ground. The remaining "L" terminal will be unused.

If your measurements do not show line voltage between only two of the "L" terminals, then the machine's internal wiring may be more complicated and you may need to do some reverse engineering to figure it out.

AllanJ 10-26-2010 09:57 PM

A 120 volt single phase motor may be wired into a 3 phase plug using L1, neutral, and ground. A 240 volt single phase motor may be wired using L1, L2, and ground. But a single phase motor or appliance that uses both 120 volts and 240 volts should not be wired into a 3 phase plug. Instead a single phase plug should be substituted.

This way, if you actually or accidentally plug it into a real 3 phase receptacle you won't damage anything.

tonyr417 10-26-2010 10:09 PM

Quote:

Originally Posted by mpoulton (Post 523265)
This sounds simple to me. Turn the machine on and operate it so that the power feeder would be running if it were attached. Measure voltage between the L1, L2, and L3 terminals in the receptacle. One pair of terminals should have 240V between them (or whatever your line-to-line voltage is). It will be L1-L2, or L2-L3, or L1-L3. Wire the motor to those terminals and ground. The remaining "L" terminal will be unused.

I spoke with the technical service department of the importer of the machine this afternoon. The machine is a multi-function combination woodworking machine made by a defunct company called "knapp". The machine weighs about 4500 lbs and much of the wiring runs through internal cabinetry and is not accessible and they feed 4 separate single phase motors as well as the 3phase receptacle in question. But that is just additional background.

They told me today to attach the ground wire to the earth terminal and the 2 hot leads to L1 and L2. The said I could confirm that those were the proper connections using exactly the method you described above, but they said it wasn't necessary as they have seen this situation arise previously. I didn't ask why the manufacturer would have wired the receptacle in this manner in the first place.

In any event, I wired the feeder but will not be able to try it until the weekend since its mechanical elements are not yet fully assembled, but I think I should be set. I appreciate everyone's help.


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