# wiring an old milling machine,have some questions.



## rynox44 (Jul 9, 2014)

A company wanted to relocate an old milling lathe, that had previously been hooked up in their building. there is a control cabinet directly on the machine, with limited access, and a disconnect in between the machine and the panel. the wires had been removed from the load side of the disconnect before I had got there. the motor nameplate says 230v 3w+N, however there is no evidence of a neutral in the control box, nor in the wires that were on the load side of the disconnect. there is a simple 3 phase wiring diagram on the nameplate, but I don't know if I should wire it that way because the machine is foreign. I should also note that although the nameplate calls for a neutral, an undersized green wire entering the control box with the 3 phase wires is bonded immediately to the control cabinet before joining the other grounds and its clearly labeled with the ground symbol. also in the disconnect where the neutral should go, a bonding screw has been used to ground the lugs to the disconnect enclosure. im not sure the rotation of the motor, but I know it has a forward and reverse, so im not sure if I could cause any serious harm, by incorrectly phasing it, since I do not know how it was originally hooked up. I should also not that there is a high leg in the building. 120 on A, 202 on B, and 120 on C, 230 between the phases. I have never worked with a high leg before, so im a little uncomfortable. my question, is there anything I have to worry about damaging, or is it just a matter of switching the phases around to get the motor to rotate the right way. they don't use any of the auxillary features of the machine. also not sure if it is relevant but when I was indentifying wires on the contact block A,B,(phases) both ring through ground. is it because itsgoing through an e-stop or the windings on a transformer. c phase isn't like that. if you need an explanation or more into, id be happy to ablige, I would just like reassurance that I cant cause any major damage....also here is the only wiring diagram on the entire machine. I drew it up. to me, I would say the first wire landed would be on a C phase, second B phase, ect from left to right....but it from a different country so IDK....thanks! and sorry for the lengthy post, Ive just been doubting myself all day!


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## Pete m. (Nov 19, 2011)

Not trying to be a smart ass but there are things called paragraphs. 

Please try to break it down into individual ideas that members can dissect and understand.

Pete


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## rynox44 (Jul 9, 2014)

pete m I got a notification via email, but I don't see it here on the thread. im sorry, im terrible at verbally explaining things. but I just basically want to know is there any damage I can cause to the machine by messing up the phasing with a high leg. I have already ruled out the grounding/neutral issue. the motor has a forward and reverse.


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## varmit (Apr 19, 2009)

Without tracing out some of the machine wiring it would be difficult to give you a definitive answer. Almost all modern machine tools are strait three phase, but I have seem some old European equipment where the Wye connection point, on motors, that was connected to the neutral. this "neutral" can be deleted from the motor connection without causing any problem.

The thing to check, would be the control power source. If there is a control transformer, Then you SHOULD be OK with your existing power distribution. If the machine is using one leg of the three phase incoming power for the control voltage, MAKE CERTAIN TO NOT CONNECT THE HIGH LEG TO THE CONTROL CIRCUIT. 

Some of these old European machines have some really unusual control formats and voltages, especially some of the machines manufactured in East Germany in the USSR days.


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## rynox44 (Jul 9, 2014)

...I cant see posts until I post. why is this?


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## rynox44 (Jul 9, 2014)

varmit, thanks for the reply. it is an old foreign machine, and I figured they disbanded the neutral. however in the control cabinet the start stop button operates on 24v but I cannot tell which phase goes to the control transformer. the cabinet has no access to the controls, really, and Im having trouble tracing wires.


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## JRaef (Mar 23, 2009)

Varmit is dead on. The only thing worth adding is that if when you said "both ring through ground" you mean that you used an ohmmeter and read conductivity between A and G or B and G, then that's just because you are reading through the transformer windings themselves, and C is your "high leg" (not supposed to be, but different areas do it differently). If nothing inside of the machine is using the Neutral, then you don't need to worry about it and given that it previously did not have a Neutral wire run to it, it probably doesn't need it. In Europe, they always have Wye power, ie 380Y220. So for control voltage, they just used a phase and neutral for 220V controls. But when those machines ended up here, that doesn't work, so people would often change out the controls for 120V, or use a separate control transformer for 220V so that it didn't matter that there was no neutral.

As to phasing, sometimes if there is some sort of mechanical device that limits travel in one direction it can be a problem, but since it is a reversing tool, I don't see how that would play out as being able to cause any permanent harm. There is likely a "drum switch" with a big lever on it, that says something like Fwd - Off - Rev. Just make sure that what the USER considers as Fwd is turning the way he wants it, and you are done.


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## rynox44 (Jul 9, 2014)

......


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## rynox44 (Jul 9, 2014)

Jraef...yes, I was measuring continuity...just wanted to identify the wires. I spliced each wire on the one end to the ground (one at a time) and then touched the leads to the phase terminals and the ground. "A" and "B" terminals were both ringing out to ground no matter which wire I touched to ground, so I had to remove them from the terminals to verify them. and just to verify, your saying I should put the high leg on "C" phase? it comes in on B phase.


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## JRaef (Mar 23, 2009)

Wait, I think I may have misunderstood you. I was thinking that you were looking at the incoming supply, now I realize you are looking at the wires on the machine. 

So if A and B are ringing out to ground, then they may have transformers or power supplies connected to them internally, and those transformers are likely the original European ones that were expecting 220V from phase to neutral. That is going to mess you up big time, because you don't have a Wye system, you have 240V delta. You may have to get inside of that control panel and find those transformers, then remove the ground/neutral connection on the primary and take whatever wire went to the old neutral and connect it to another phase of the US 240V 3 phase you have.**

European machines can be a real mess for us electrically, people who buy them cheap and ship them here never think about that, then they're always pissed at us when we break the bad news.

** There is another possibility. 
It could be that someone already modified the controls here and installed some Switched Mode Power Supplies for 24VDC controls. Some of those can accept anything from 100-295VAC input, they are auto-ranging (so to speak). So if they did, then A to ground would be 120V, no problem, and B to ground would be 208V, which may still be OK for the power supply. If there is no Neutral wire run to the machine, that would have been a code violation, but we all know that DIYers do that all the time. Even with a Neutral wire, the B to G would still be a violation, you would have to find that one and move it to C, then you would have to run a Neutral conductor. It might be easier to just find them, see what you have, then do what I said first; re-wire them as 240V phase-to-phase to eliminate that neutral.


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