Centroid Community CNC Support Forum

There are a number of wires I will be connecting between the Acorn board and my VFD that runs a 2.2kw spindle. Do you have a recommendation on the type of wire to use? For instance, should I use a single cable with 8 18 gauge wires? Should it be a shielded cable? Or, is 20 or 22 gauge all I need? Would 2 cables with 4 wires each be better? Or what?

https://youtu.be/tGDFUtkd52A

https://youtu.be/bX7lBZ2HyJ8

cmorgan wrote: ↑Tue Sep 04, 2018 10:29 am There are a number of wires I will be connecting between the Acorn board and my VFD that runs a 2.2kw spindle. Do you have a recommendation on the type of wire to use? For instance, should I use a single cable with 8 18 gauge wires? Should it be a shielded cable? Or, is 20 or 22 gauge all I need? Would 2 cables with 4 wires each be better? Or what?

18 gauge shielded cable.
Ground the drain wire at one common ground tie point in the control cabinet.

Keith provided links to a couple of videos I did where I benchtested an Automation Direct GS1 drive and motor. On the benchtest I did not use the 18 gauge cable, but will when I permanently wire the control in the cabinet.

Marty

Thanks, Marty. I picked up some 4-wire, 18 gauge, shielded cable for the Acorn-to-VFD control wiring.
(I'm waiting on getting an order of 4-wire, 16 gauge, double-shielded cable for the VFD-to-spindle wires.)

cmorgan wrote: ↑Thu Sep 06, 2018 10:41 am Thanks, Marty. I picked up some 4-wire, 18 gauge, shielded cable for the Acorn-to-VFD control wiring.
(I'm waiting on getting an order of 4-wire, 16 gauge, double-shielded cable for the VFD-to-spindle wires.)

Generally, you need 8 conductor for VFD:

Analog 0-10VDC spindle out
Analog 0-10VDC spindle com
FWD
REV
RESET
FWD/REV/RESET COM
VFD FAULT OUTPUT
VFD FAULT COM

Why is 18 gauge wire being recommended? These are all signal lines. Should they carry very little power.

mikes wrote: ↑Thu Sep 06, 2018 8:41 pm Why is 18 gauge wire being recommended? These are all signal lines. Should they carry very little power.

Yes, they do. However I have experienced issues with using a small gauge wire for the spindle analog signal. I have noted others have as well. I believe Centroid recommends and sells 18 gauge wire for VFDs connection. Perhaps Keith can confirm.

I do what works reliably for me based on personal experience. It's not worth saving a dollar or two for me. Same with encoder cable. While I have used stranded shielded Ethernet cable, I now use the same cable that Centroid recommends and sells. They've proven it and stand behind it.

Certainly each individual can choose what they'd like to use and works for them. I'm doing too many conversions lately and need to stick with proven components. Including motors, drives and VFDs.

Marty

Marty, my supplier didn't have 8-wire 18-gauge cable. So, I figured I'll just use 2 4-wire cables to the VFD.

mikes wrote: ↑Thu Sep 06, 2018 8:41 pm Why is 18 gauge wire being recommended? These are all signal lines. Should they carry very little power.

Often a larger gauge is easier to work with. It also stands up better to abuse like vibration, over tightening, over stripping with incorrect tools, etc. Larger wire also has lower resistance, which can be significant for ground wires.

I would use the largest gauge that is easy to work with, even though it is overkill as far as current carrying capability.