24vdc power supplies

[craig_avanzar]

I know there are sandy parts of Texas where 3 rods in a loop would not be enough to achieve a 25 ohm path-to-ground.

Yes that is correct. I don't know of a way to check the system. You see during that talk w/ facilities guys part of their problem is that the rods are covered in the slab. Not the best idea I've ever heard but I'm no EE. I even asked if they had megged the rod points and they said that a certain car manufacturers' engineering dept. said to cover it over w/o a test. I don't know what they know.

Identify the noise source. That's what needs a ground.

Yes that is my objective I believe.

Subtract the square wave first, so you can see the noise.

I am not that proficient with the scope to understand what you are describing. Can you elaberate?

Can you scope the line unpowered?
Can you scope the ground?

I will try both of those in about an hour when the crew takes their break. Production.

Lancie1, Mordred, Keithkyll thanks for your help and responses. I will post back with my results.

Anxious in S.A.

 

[Lancie1]

You see during that talk w/ facilities guys part of their problem is that the rods are covered in the slab.

Then you have the deluxe Ufer grounding method, the best you can get for any soil type. Do a search for "Ufer grounding" and you will find that many cities in the sandy west have adopted this as the ONLY approved grounding method.

Now make sure that all your noise-producing equipment IS connected to the Ufer grounding system. I bet there was one motor that was overlooked, maybe only grounded through a conduit or other undependable ground conductor.

 

[craig_avanzar]

Will do. I'll also read up on the Ufer grounding while I wait for the machine time.

Thanks Lancie1,

 

[craig_avanzar]

Screen shot

screen shot didn't take. working on it.Just being curious I tried recording the wave form so I could post what I see. This is not the usual square wave pattern I view but going through the scan I noticed this. I had been trying to switch on different motors and record the effects on the wave. I believe this happened when the contactor pulled in for one of the servo motors on the robot. I do believe that we have a true grounding/noise issue. Still working on recording the square wave. Never did this before and the book is not helping me.

 

[keithkyll]

Subtract the square wave first, so you can see the noise.

I am not that proficient with the scope to understand what you are describing. Can you elaberate?

Figure of speech. You might be able to do such a thing with a storage scope, but I meant do it mentally, then try to find a source that looks the same.
We want to find a way to view just the noise.
The 2 examples that followed are ways to do this.
Sorry for not being clear.