3 phase wiring help needed

[TRPrecision/se3racer]

Just added a big used milling machine to the shop. It was wired for 440v 3 phase at the last location, I am going to run it with 230v single phase via VFD. The VFD i have covered, the motor votage change rewire is the problem. Upon opening the box on the motor, I found the terminal plate and wire tags missing, numbers were hand written on masking tape on the wires, but only legible on 2 of the 12 wires.
I need an electrician or electrical engineer / guru who understands 3 phase motor wiring well enough to determine what leads are what and can help me re wire to run 220v 3 phase.
Any suggestions would be greatly appreciated

 

[beaver]

Use a phase converter about a 100 bucks that’s what I done on my 12 foot lathe took less than 15 minutes to wire up works great

 

[moosensquirrel]

What is the motor rpm and HP? If you are certain that the motor is connected for 440v, the motor phase coils are wired in Delta. For 220v, connect the coils in wye (star).

The second diagram is for a 12 wire motor, 2 pole 3600 rpm nominal.

Easiest way is to take the motor to an electric motor shop that rewinds motors and have them identify the poles and lead connections, and make the 220v connections for you. A genuine industrial electrician can probably do this, but a construction electrician probably not.

YMMV do not attempt this at home if you are uncertain. Load current for the 220v connection will be about double the 440v connection and may require a larger circuit depending on VFD

 

[Dice]

Just added a big used milling machine to the shop. It was wired for 440v 3 phase at the last location, I am going to run it with 230v single phase via VFD. The VFD i have covered, the motor votage change rewire is the problem. Upon opening the box on the motor, I found the terminal plate and wire tags missing, numbers were hand written on masking tape on the wires, but only legible on 2 of the 12 wires.
I need an electrician or electrical engineer / guru who understands 3 phase motor wiring well enough to determine what leads are what and can help me re wire to run 220v 3 phase.
Any suggestions would be greatly appreciated

unless I've missed something lately the variable frequency drives are sold as single phase or three phase units. Changing the motor leads to run on single phase 208/240 will require a phase converter THEN a freq drive if you need to control speed of the mill.

 

[4ssss]

variable frequency drives are sold as single phase or three phase units.

They have all kinds of VFD's now. The 2 that I have on my machines convert 3 phase to single phase, but I stuck with the 220v. I can can control the speed, but I avoid that by changing belt pulleys. I heard that the slower a 3 phase motor runs from 60 hz it has a greater chance of overheating with the slower internal fan.

 

[TRPrecision/se3racer]

What is the motor rpm and HP? If you are certain that the motor is connected for 440v, the motor phase coils are wired in Delta. For 220v, connect the coils in wye (star).

The second diagram is for a 12 wire motor, 2 pole 3600 rpm nominal.

Easiest way is to take the motor to an electric motor shop that rewinds motors and have them identify the poles and lead connections, and make the 220v connections for you. A genuine industrial electrician can probably do this, but a construction electrician probably not.

YMMV do not attempt this at home if you are uncertain. Load current for the 220v connection will be about double the 440v connection and may require a larger circuit depending on VFD

View attachment 4773918
View attachment 4774045

The motor is 100% wired in 440v It came out of a machine shop that was upgrading to all CNC. We cut the wires from the 440v supply after seeing the mill run.
It is 3hp 1750 rpm. I might take it to a motor shop if I can figure out how to get it off the mill head...
here is a look inside the motor power box...

 

[TRPrecision/se3racer]

Use a phase converter about a 100 bucks that’s what I done on my 12 foot lathe took less than 15 minutes to wire up works great

I dont want to give up 1/3 of the power you lose with a phase convertor. I run VFD on my other equipment and it is the only way I will go.

 

[TRPrecision/se3racer]

unless I've missed something lately the variable frequency drives are sold as single phase or three phase units. Changing the motor leads to run on single phase 208/240 will require a phase converter THEN a freq drive if you need to control speed of the mill.

The VFD takes a single phase 240v input and puts out 220v 3 phase. Running the same unit on my other equipment

 

[TRPrecision/se3racer]

They have all kinds of VFD's now. The 2 that I have on my machines convert 3 phase to single phase, but I stuck with the 220v. I can can control the speed, but I avoid that by changing belt pulleys. I heard that the slower a 3 phase motor runs from 60 hz it has a greater chance of overheating with the slower internal fan.

The mill has variable speed head, not step pulleys. I will run the motor at full speed 90% of the time.

 

[roundhouse]

I have a few motors with the wiring diagrams on them for the different voltages but it will be a couple days before I can get to them to take a pic .

Usually they are able to use 220 or 480
Depending on which wires are tied together .
The wire numbers are universal
But if you’re wires don’t have numbers on them , that’s gonna be a problem