AC power cable in the same cable carrier with motor cables

[bandtank]

Would there be an issue with running an AC power cable (to a router) in the same cable carrier as the motor cables and limit switch cables? I am wondering if there is any possibility of interference or damage resulting from the proximity of these various wires.

If it matters, the motor driver is a Gecko 540 and it will be driving three 280oz steppers. I don't know what kind of power supply I'll be using yet (linear vs switching) but if that matters please feel free to chime in. Also, and I know this isn't very related to the topic, but if you have any recommendations on which type of power supply to use I would really appreciate it. I've searched these forums and have no found any suitable answers.

[Al_The_Man]

Normally on a large gantry with a cable carrier there is not alot of choice but to run motor and control together, as long as all cables, including motor feeds are twisted together.
It would pay to run low level limits switch conductors in shielded cable, it can pay to adopt the industrial control method of using a higher voltage, 24vdc for example.
make sure you take a good ground conductor to the gantry and motor frame.
Steppers are usually low impedance devices and radiate more than pick up noise.
Al.

[bandtank]

I don't think I can change the voltage on the limit switches with the G540 unless I am reading the manual wrong. It looks like they are internally pulled high and you switch them to ground.

Are you saying I should screw a ground terminal connection into the frame of the machine or that I should a ground wire through the cable carrier with the others? My spindle is a router that will be running off of 120VAC just to be clear. It will not be VFD.

My motors will be running off of 40-50VDC. I forgot to mention that earlier.

[Al_The_Man]

You should run a ground wire through the carrier to the gantry from and the spindle motor frame, unless it is fed from 3 wire cable.
It pays to take one to the gantry frame anyway to bond the gantry to the common earth point you should have set up in the panel.
Al.

[D O N]

The two issues would be interference/noise, and electrical safety.

Noise can be addressed with shielded low voltage cables, with the shielding grounded at one end only (to prevent ground loops), usually not the gantry end.

Electrical safety is when the insulation fails and dangerous voltages become exposed. Generally not a problem, but putting the high voltage (120VAC) cable inside a secondary insulator (such as braided wire covering) can't hurt. This Link shows what this material is; surely there are hundreds of suppliers for this stuff.

Don

[johnmac]

I don't want to hijack the thread, But I am building a steel framed router table with a Porter Cable router for the spindle. The router has a ground wire in its power cord. How should this ground be connected to prevent a ground loop within the gantry?

John

[Crevice Reamer]

It's not the higher Voltage circuits where you need to worry about ground loops--Just the shielding on the low voltage homes/limits wires.

Personally, I would not mix 60 Hz AC (OR pulsing motor wires) with my low Voltage wires unless the AC was shielded.

CR.

[Al_The_Man]

There is some confusion about the difference between ground loops and bonding.
The difference is that on shielded cables that carry low voltage signals you do not want the shield to inadvertently carry a ground current through the shield, so in this case only one end is connected to earth ground to avoid any ground loop current.
The object of bonding, which is running a conductor to all metallic parts of the machine and motor frames is to try and achieve what is called a uni-potential bond, essentially what you are trying for is to make sure that there is no difference in potential between any part of the machine frame and another.
I have several references but most are too large to post.
You should also take a ground wire from the gantry itself to the central ground point in the enclosure.
Also power conductors that are twisted together tend to self cancel radiated energy.
Al.

[johnmac]

Thanks for the replies. My AC isn't shielded, but it does have a gentle twist. I have a 3" cable track with the AC fastened along one end, followed by an air hose, shielded stepper wires, then shielded limit switch wires. All wiring is run and clamped down. I'm ready to make the connections. If anyone sees a problem, speak up now!

John

[Crevice Reamer]

Originally Posted by johnmac Thanks for the replies. My AC isn't shielded, but it does have a gentle twist. I have a 3" cable track with the AC fastened along one end, followed by an air hose, shielded stepper wires, then shielded limit switch wires. All wiring is run and clamped down. I'm ready to make the connections. If anyone sees a problem, speak up now! John

I think you're adequately covered, John. Just be sure the shielded motor/limits drain wire is grounded on the driver end.

CR.

[johnmac]

Thanks, Crevice. I'm hoping not to have to back up and re-work, but now would be better than later!

Thanks, Al. Your reply helps a lot. It cleared a few things up in my mind.

I've played with electricity/electronics since I was a kid, but everything I know is self taught, so there are plenty of holes in my knowledge. Now there is one less.

I now return this thread to its rightful owner!

John

[Al_The_Man]

Originally Posted by bandtank I don't know what kind of power supply I'll be using yet (linear vs switching) but if that matters please feel free to chime in. Also, and I know this isn't very related to the topic, but if you have any recommendations on which type of power supply to use I would really appreciate it. I've searched these forums and have no found any suitable answers.

Although as a rule both types will work, switching and/or regulated is not really required for servo/stepper use.
I always use linear supplies, they are generally much more rugged, and in the event they do fail, are much easier to fix.
Switching are generally lighter and more compact. This is the only real advantage as far as I can see.
Al.