Need Help!- Power Supply Basics

[54Oval]

I guess the only dumb question is the one not asked. I am finally getting back to my CNC project and I'm second guessing my grounds. I just want to be sure everything is OK before I smoke something expensive.

I'm using Keiling brushed DC motors, Gecko 320's and a homebuilt powersupply. Everything resides in a big steel enclosure. The ground wire from the wire supplying AC current is connected to the case. The power supply's negative terminal from the capacitor is also grounded to the case. Finally the green lead from each of my DC motors are connected to the case. Is this correct? Thanks for your help

-Dan

[Mr.Chips]

Don't forget to ground the shielded lines from the drivers to the stepper motors, but only at the driver ends. Don't ground the shielding at the stepper end.

OK it time to post some pictures for Show and Tell.

Good luck

[Monte]

Originally Posted by 54Oval I guess the only dumb question is the one not asked. I am finally getting back to my CNC project and I'm second guessing my grounds. I just want to be sure everything is OK before I smoke something expensive. I'm using Keiling brushed DC motors, Gecko 320's and a homebuilt powersupply. Everything resides in a big steel enclosure. The ground wire from the wire supplying AC current is connected to the case. The power supply's negative terminal from the capacitor is also grounded to the case. Finally the green lead from each of my DC motors are connected to the case. Is this correct? Thanks for your help -Dan

If I understand what you've said, it doesn't sound good to me. I don't think you really want to use your chassis ground as the ground path for your drivers or the neg term of the capacitor. Hook the neg term from the cap directly to the drivers (320's), a wire from each driver to the cap term. Ground the end of the cable shielding to the enclosure and the enclosure to the ground wire of the AC supply like you have done. I don't think I've seen a schematic with the neg term grounded to the enclosure.

Monte

[Al_The_Man]

Originally Posted by Monte I don't think I've seen a schematic with the neg term grounded to the enclosure. Monte

I do this all the time with the systems I install, I ground all power supply commons to a common ground plate, together with service ground and any local created neutral.
And all shields.
Al.

[Monte]

Originally Posted by Al_The_Man I do this all the time with the systems I install, I ground all power supply commons to a common ground plate, together with service ground and any local created neutral. And all shields. Al.

Okay. I wouldn't have thought that was a good way to do it. Seems like it would be a little more convenient for wiring.

Monte

[Al_The_Man]

Originally Posted by Monte Okay. I wouldn't have thought that was a good way to do it. Seems like it would be a little more convenient for wiring. Monte

It has been fairly common for a while, but the ground is NOT to be used used in place of a regular conductor path, it is used as a reference only, supply conductors are still run as normal.
All metallic structures and enclosures are all bonded together.
Al.

[Monte]

Originally Posted by Al_The_Man It has been fairly common for a while, but the ground is NOT to be used used in place of a regular conductor path, it is used as a reference only, supply conductors are still run as normal. All metallic structures and enclosures are all bonded together. Al.

I can understand and do bond the metallic structures and enclosures together, but I'd never have thought to ground the negative terminal of the power supply capacitor to the enclosure too.

I guess it's the same for house wiring, the ground and neutrals are bonded together.

Monte

[Al_The_Man]

Originally Posted by Monte I guess it's the same for house wiring, the ground and neutrals are bonded together. Monte

Yes, and the SERVICE neutral and ground should only come in contact with each other at the service panel.
I should point out this is my personal philosophy on Non-Isolated system, as opposed to complete isolation between systems.
After all safety concerns are addressed, it is a matter of personal preference.
I am not declaring either way as right and wrong.
Al.