[How-To] Wire 440v mill for 220v

682bear

682bear

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Last week, I acquired on old Cincinnati #2ML universal horizontal mill. The company that was selling it had it advertised as a 220v 3 phase machine. After driving 353 miles to pick it up, I noticed a big '440V' sticker on the main power cutoff box...

The company maintenance guy was there, I asked him about it... he said it could be wired to run off of 220 3 phase, so I went ahead and loaded it up and brought it home.

I think I may have it figured out, but wanted some 'reassurance' before I blow something up...

20201109_094808.jpg

This is the transformer in the machine column... it is currently wired for 440v.

According to what I'm reading on the transformer, do I simply need to run a jumper wire from H1 to H3, and another from H2 to H4 to power it with 220v 3 phase?

The control voltage is 110v... if that makes any difference. If this is correct, is there anything else that I need to look at changing?

I'm trying not to burn my house down, any advise would be greatly appreciated...

-Bear
 
The photo you show looks like it takes either 230 or 460v input and outputs 115v.

You're reading things correctly re: rearranging the jumpers for 230v power

(1) Remove the jumper from H2 to H3
(2) Install a jumper from H1 to H3
(3) Install a jumper from H2 to H4


BUT!!!!!

This, to me, looks like only a transformer to get the 110V control voltage.

You probably need to do a similar re-wiring within the motor hookup box (attached to the motor). In all likelihood, the main motor for the machine can also be run on either 220 or 440v. You'll need to rewire the motor as well before you start everything up.
 
JRaut said:
The photo you show looks like it takes either 230 or 460v input and outputs 115v.

You're reading things correctly re: rearranging the jumpers for 230v power

(1) Remove the jumper from H2 to H3
(2) Install a jumper from H1 to H3
(3) Install a jumper from H2 to H4


BUT!!!!!

This, to me, looks like only a transformer to get the 110V control voltage.

You probably need to do a similar re-wiring within the motor hookup box (attached to the motor). In all likelihood, the main motor for the machine can also be run on either 220 or 440v. You'll need to rewire the motor as well before you start everything up.
Click to expand...

Yes, I forgot that part... I had also determined that I will have to rewire the motor for 220v... it is a 220/440 motor.

Is that pretty much all there is to it?

I've never rewired a motor before... there is a tag in the control box detailing how. I think maybe I can figure it out. Maybe...

Thanks!

-Bear
 
There's often a motor data plate also that shows how to configure it
-Mark
 
The info on how to wire the motor should be on or in the motor.

Check for any other motors that might also need to be changed. Look around for any other transformers that need to be switched.
The good thing is that if you do miss something it most likely will not work correctly, but you are not likely to let out any of the magic blue smoke that all electronics runs on.

When I got my mill they said the x drive motor was bad and had not worked for 30 years, I found the the main motor was correctly wired for 220 and the x drive motor was still wired for 440. Changed the wires and it worked fine.
 
Last edited:
A couple of other things to consider. If the machine uses a magnetic starter with overload protection (heaters) for the motor, you will need to change the heaters. The heaters for 220V will be double the current rating of the 440V heaters. Also, if your 3 phase power source is from an RPC (or other phase converter), do not use the generated leg to power your control transformer.

Ted
 
talvare said:
A couple of other things to consider. If the machine uses a magnetic starter with overload protection (heaters) for the motor, you will need to change the heaters. The heaters for 220V will be double the current rating of the 440V heaters. Also, if your 3 phase power source is from an RPC (or other phase converter), do not use the generated leg to power your control transformer.

Ted
Click to expand...

Ok, the magnetic starter would be a contactor, correct? If so, yes, it does have a contactor... how would I go about figuring out whether it has the heaters?

I rewired the motor for 220v this afternoon... I have not rewired the transformer yet. I still have some other things that need to be done before I can attempt to run it. There is a cracked sight glass that is leaking that needs to be repaired, I need to check and top off all the different oil reservoirs, and it needs new drive belts.

And a good cleaning... I started that this morning.

Thanks- Bear
 
Bear,
Yes, a contactor with an overload block attached. Here's an example:
In that photo, the heaters screw into the lugs you see on the bottom section of that starter (there are no heaters installed in that photo). The heaters have a specific current rating that you select based on the current rating of your motor. You may actually be able to get by with the heaters that are installed for the 440V application if you put very light loading on the motor. But with any significant load, they will trip long before you get to the capacity of the motor. Here is an example of a heater (thermal overload):

Ted
 
talvare said:
Bear,
Yes, a contactor with an overload block attached. Here's an example:
In that photo, the heaters screw into the lugs you see on the bottom section of that starter (there are no heaters installed in that photo). The heaters have a specific current rating that you select based on the current rating of your motor. You may actually be able to get by with the heaters that are installed for the 440V application if you put very light loading on the motor. But with any significant load, they will trip long before you get to the capacity of the motor. Here is an example of a heater (thermal overload):

Ted
Click to expand...

Ok, there are 2 General Electric CR-124 overload relays installed on the contactor... a quick google search tells me these are rated at 27 FLA, 10A contact rating... the motor should draw 8.4A @230V.

Do I need to swap these out?

I have a basic working knowledge of how all this works together, but I'm no expert...

Thanks-Bear

Edit: this is what the internet gave me:

Screenshot_20201116-145253_Chrome.jpg
 
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