Need wiring advice for a 3phase cnc

Erstwhile · Feb 8, 2020

Need some help wiring up my cnc, the previous owner had a 3 wire twist lock plug on it. I have 4 wires including a ground coming out of my phase converter which is what I thought you had to have to run a 3 phase machine. The wires on the plug they have is a Green wire connected to the G terminal a white wire connected to the T, and a Black wire connected to the R. So did they have it wired wrong? I know very little about 3 phase I've attached pictures of the wiring, wiring diagram from the machine and the phase converter and the plug. I'd like to just directly wire from the phase converter and do away with the plug all together, any help/advice is greatly appreciated.

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Dan from Oakland · Feb 8, 2020

Lines T,S and R are your three power leads. The "G" is a safety ground. Take that twist lock and throw it away. That is a single phase 20 amp connector with ground. The previous owner was running the machine with only the phase conductors and no safety ground. From what you wrote, they were using 3 conductor cord rather than 4 conductor, and using the ground lug in the twist lock for a phase conductor.
If you are going to use a cord to connect the machine, get some 4 conductor cord. Just FYI, 20KVA at 220 volts is about a 50 amp load. A 50 amp load with rubber cord requires about #6 AWG conductors. You are probably never going to run the machine to its maximum rated load, so you most likely can get by with 8AWG cord that is rated for 40 AMPS.

Erstwhile · Feb 8, 2020

Dan from Oakland said:
Lines T,S and R are your three power leads. The "G" is a safety ground. Take that twist lock and throw it away. That is a single phase 20 amp connector with ground. The previous owner was running the machine with only the phase conductors and no safety ground. From what you wrote, they were using 3 conductor cord rather than 4 conductor, and using the ground lug in the twist lock for a phase conductor.
If you are going to use a cord to connect the machine, get some 4 conductor cord. Just FYI, 20KVA at 220 volts is about a 50 amp load. A 50 amp load with rubber cord requires about #6 AWG conductors. You are probably never going to run the machine to its maximum rated load, so you most likely can get by with 8AWG cord that is rated for 40 AMPS.

That's what I was thinking they weren't using a ground but one of the wires dose go to the G terminal, so how did it even run?

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Lakeside53 · Feb 8, 2020

The machine does not need ground to run; you need ground to stay alive.

If you have multiple machines, run it though a fused disconnect.

Erstwhile · Feb 8, 2020

I understand that but, I guess what I'm getting at is they only had a wire running to the R and the T, and then another to the G which is ground correct?

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Tryhard · Feb 8, 2020

Erstwhile said:
That's what I was thinking they weren't using a ground but one of the wires dose go to the G terminal, so how did it even run?

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Consider that the plug and wire in your picture are single phase power coming OFF of your CNC machine.
Probably for a pump of some sort.
Look for incoming L1 L2 L3 terminals on your drawings and on your machine. They shouldn't be shared with other wires. And 'should' go from there to a K1 K2 K3 contactor which is basically a heavy power relay for powering up your machine with a lil' button instead of a big ass Frankenstein looking switch.

Cheers!

Dan from Oakland · Feb 8, 2020

Ah- never thought of that- you are probably correct as that's a NEMA receptacle and not a plug!. T,S and R are still the phase conductor terminals for power into the machine along with the safety ground. Note the power schematic is also showing a neutral connection as well as the ground?

Erstwhile · Feb 8, 2020

Dan from Oakland said:
Ah- never thought of that- you are probably correct as that's a NEMA receptacle and not a plug!. T,S and R are still the phase conductor terminals for power into the machine along with the safety ground. Note the power schematic is also showing a neutral connection as well as the ground?

Ok that makes sense why it's a receptacle sense you wouldn't want the hot leads exposed. So is that connector just like a 220v single phase auxiliary connector?

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Tryhard · Feb 8, 2020

Ah- never thought of that- you are probably correct as that's a NEMA receptacle and not a plug!. T,S and R are still the phase conductor terminals for power into the machine along with the safety ground. Note the power schematic is also showing a neutral connection as well as the ground?

But what is on the previous page of your schematic?

What machine is that? Bridgeport R2E4?

Erstwhile · Feb 8, 2020

Tryhard said:
But what is on the previous page of your schematic?

What machine is that? Bridgeport R2E4?

Ite leadwell 1000 , I'll post more pictures in just a little bit, I'm guessing the terminals I pictured before aren't were you actualy connect the power supply now.

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Tryhard · Feb 8, 2020

Erstwhile said:
Ite leadwell 1000 , I'll post more pictures in just a little bit, I'm guessing the terminals I pictured before aren't were you actualy connect the power supply now.

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Follow some wires backward from those terminals and see where they go. Start with the heavy wires.

Tryhard · Feb 8, 2020

Erstwhile said:
Ite leadwell 1000 , I'll post more pictures in just a little bit, I'm guessing the terminals I pictured before aren't were you actualy connect the power supply now.

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But yeah, Look for L1 L2 L3 for the main power in lugs. Should be marked as such.
Who knows with the tiawan machiine though. Maybe T1 T2 T3 as main lines or contactors K1 K2 K3

Erstwhile · Feb 8, 2020

Tryhard said:
But yeah, Look for L1 L2 L3 for the main power in lugs. Should be marked as such.
Who knows with the tiawan machiine though. Maybe T1 T2 T3 as main lines or contactors K1 K2 K3

Alright here's some some pictures there aren't any terminals labeled with L or T but I think this is where you connect power, let me know if you agree

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Erstwhile · Feb 8, 2020

Erstwhile said:
Alright here's some some pictures there aren't any terminals labeled with L or T but I think this is where you connect power, let me know if you agree

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The lines connected to that terminal run directly to the on/off breaker on the outside of the machine

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Erstwhile · Feb 8, 2020

Tryhard said:
But yeah, Look for L1 L2 L3 for the main power in lugs. Should be marked as such.
Who knows with the tiawan machiine though. Maybe T1 T2 T3 as main lines or contactors K1 K2 K3

Got it running, thanks for all the advice everyone

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Tryhard · Feb 9, 2020

Erstwhile said:
The lines connected to that terminal run directly to the on/off breaker on the outside of the machine

Yeah, the on/off breaker is the L1 L2 L3.
If you are running a phase converter, then it may matter which lug the created leg is on.
Example, on a haas I'm told it would be created leg on L2.

Glad you got it working! Post some pics of it!

Cheers!

Erstwhile · Feb 9, 2020

Tryhard said:
Yeah, the on/off breaker is the L1 L2 L3.
If you are running a phase converter, then it may matter which lug the created leg is on.
Example, on a haas I'm told it would be created leg on L2.

Glad you got it working! Post some pics of it!

Cheers!

I'll post some pictures soon, having issues with the machine homing now, and it's only getting like half of its Y travel, hopefully it's just beacuse I haven't leveled it yet

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13engines · Feb 9, 2020

I may get some push back about this, but I ran machines for years like this in my garage.

The two wires from the single phase or house side of your system that are connected to L1 and L2 in your phase convertor, are the same ones you want to be connected to the R and S terminals in your machine that connect to the NC Transformer. This is the best way to do this. If you look closely in your rotary phase convertor cabinet, you may or may not be able to discern the true path of the two single phase wires after they leave the output side of the L1 and L2 connection block. I'm sure they head to the motor or capacitors, but there also may be a direct jumper from them to the output terminals of your phase convertor. If so, follow those and make sure they're what you use for R and S. That is if R and S are still connected as they are written in the manual. Though things look pretty messy in the bottom of your cabinet. Still connected as written could be doubtful.

I couldn't stand the sound of a phase convertor running while I was trying to think, so I put it in the basement remote controlled from the garage. I got the single phase power for the phase convertor off the sub-panel in the basement. Meaning all the machines in the garage were for all practical purposes, connected directly to the single phase system. I only brought back a single wire from the basement. Sometimes referred to and labeled as such as the Manufactured Leg by rotary phase people. This fed one rail in a 3 phase breaker box I had in the garage to feed the machines. You may be able to do something like this also.

Finally, pay attention to pumps of any kind on the machine and make sure they are turning the right direction. If not, swap R and S and no others to correct that. Many machines will turn the spindle in the proper direction regardless of how the thing is wired. Pumps and less intelligent motors don't have that luxury and need to be verified immediately on first time start up. If there is an oil pump supplying a reduction gear box or something like that and it's running backwards, it's going to have problems sooner then later. Typically if one pump is running properly they all are, but it never hurts to double check them all.

Not trying to be the barer of bad news, just hoping to help to get it done right.

Erstwhile · Feb 9, 2020

13engines said:
I may get some push back about this, but I ran machines for years like this in my garage.

The two wires from the single phase or house side of your system that are connected to L1 and L2 in your phase convertor, are the same ones you want to be connected to the R and S terminals in your machine that connect to the NC Transformer. This is the best way to do this. If you look closely in your rotary phase convertor cabinet, you may or may not be able to discern the true path of the two single phase wires after they leave the output side of the L1 and L2 connection block. I'm sure they head to the motor or capacitors, but there also may be a direct jumper from them to the output terminals of your phase convertor. If so, follow those and make sure they're what you use for R and S. That is if R and S are still connected as they are written in the manual. Though things look pretty messy in the bottom of your cabinet. Still connected as written could be doubtful.

I couldn't stand the sound of a phase convertor running while I was trying to think, so I put it in the basement remote controlled from the garage. I got the single phase power for the phase convertor off the sub-panel in the basement. Meaning all the machines in the garage were for all practical purposes, connected directly to the single phase system. I only brought back a single wire from the basement. Sometimes referred to and labeled as such as the Manufactured Leg by rotary phase people. This fed one rail in a 3 phase breaker box I had in the garage to feed the machines. You may be able to do something like this also.

Finally, pay attention to pumps of any kind on the machine and make sure they are turning the right direction. If not, swap R and S and no others to correct that. Many machines will turn the spindle in the proper direction regardless of how the thing is wired. Pumps and less intelligent motors don't have that luxury and need to be verified immediately on first time start up. If there is an oil pump supplying a reduction gear box or something like that and it's running backwards, it's going to have problems sooner then later. Typically if one pump is running properly they all are, but it never hurts to double check them all.

Not trying to be the barer of bad news, just hoping to help to get it done right.

Yea initially I had it wired wrong, chip augers filled the coolant tank lol. Switched one of the wires and everything is going good other than I cant get the x and y to home and the y only seems to make about half of its 20 inch travel before alarming out

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Hardplates · Feb 9, 2020

People are jumping to conclusions saying you always need 4 wires with 3 phase. There is nothing wrong with only 3 wires if you are running corner grounded delta. A 4th ground wire would be redundant. You also only need to run 2 legs through breakers so a simple single phase panel and breakers works for 3 phase.

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