More Questions on Grounding

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eldonb46

eldonb46
The Masso installation instructions implies that only one ground connection is necessary for operation, that ground pin is near the plus voltage supply pin, as per: https://docs.masso.com.au/getting-started-guides/installing-masso/powering-masso-g3

I have read the and understand the installation notes, and I have search other Documentation and Forum, but still have some questions.



Questions:

o To help with our noise problem, can we connect ALL of the other grounds to the same power supply ground is star ground arrangement?

o Is there any reason we should NOT connect all of the grounds together at the power supply?

o Should the power supply negative terminal be "earth grounded" or left floating as it is on many DC supplies?

o Similarly, can all of the Masso Red Plus Voltage terminals be externally connected to the same single 1 Amp Fuse? Would there be any harm/advantage?



Thanks,

Eldonb

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breezy

breezy

Moderator
@eldonb46

Eldonb,

The use of the term GND is a bit of a misnomer, it dates back to the early days of radio when you had to provide a "ground/earth" point to complete the antenna circuit, but in MASSO's situation it is the negative side of the power supply not a ground/earth connection.

All electronic devices that connect to MASSO should have their power supply negatives connected to MASSO's power supply negative. Use a negative busbar.

All grounds/earths should be connected together again use a busbar, this maybe connected to the negative busbar.

From MASSO's install documentation
CAUTION: Power and Ground terminals provided on the controller are only to be used for very low current signals. Connecting high current loads can damage the controller beyond repair.
Click to expand...

So the ONLY connections to the RED power & BLACK GND terminals on MASSO should be to signaling sensors and/or switches.

Ross Woolley (@ross) has created a video on how he provided the ground system on his plasma.

Regards,

Arie.
 
E

eldonb46

eldonb46
Arie,

Thanks for the info,

I think I understand and have previously implemented the "Negative BusBar" as suggested (I think). But I think the Masso System does not allow for complete "single point grounding" compliance.

That is: Because the VGA Display Cable Shield conductor is connected internally to the Masso GND and to a Display Monitor on the other end, which is maybe plugged-in with its own Power, Neutral and Earth system. Therefore stray ground currents ( or line or EMF noise ) will travel one-way-or-the-other on the VGA cable shield.

In my current Masso Configuration, the "Negative BusBar" is NOT tied to "Earth", and therefore my questions and because I thought it was floating. But actually, after much closer inspection (just now) it appears Masso is actually "Earth'd" via the VGA Display cable shield and which is connected (in our case) to another power receptacle, which maybe on the other side of the 110/110v split phase.

Due to a previous grounding accident, where I actually let the "smoke out" of three very small "grounding" resistors within the Masso, and because I have micro electronic expertise, I was able the replace the resistors and recover. While inspecting the Masso board it appears that there maybe several separate ground-sections on the board, that are isolated from each other via these very small resistors. The reason I proposed the multiple grounding BusBar questions is because I want to avoid another accident and I do not have details of the board layout and looking for advice. Also, I am currently fighting an occasional Noise and/or USB DropOut problem which shielding/grounding may solve.

So back to my question:

o Should the multiple Black GND connections on Masso be connected to the "Negative BusBar"?

----- if NOT, sections of the Masso Board are subjected to bad things if an accidents happens (as in my case), or some part of the system fails or shorted out (i.e. a monitor).

----- Because the Monitor may be connected to another receptacle (and may be not share the same Earth until the distant main breaker panel) any EMF or Noise picked up via the VGA cable shield may travel back through the Masso controller, across the board, to a single ground pin ( the power connection as show in the installation documentation ). From my previous repair inspection it appears that the USB connectors shares the same internal ground as the VGA Cable (details actually not known). Note: We have experienced some USB DropOuts and sill looking for a long term shielding/grounding solution.

o Should the "Negative BusBar" be "Earth'd"? -- At present our "Negative BusBar" is NOT "Earth'd".

----- if NOT, then with our current configuration, the Masso Negative (-ve) will be ONLY "Earth'd" via the VGA Display Cable Shield (which I think is a bad idea).

A picture showing all of the grounds, including the power supply, Negative BusBar, the ToolSetter, Tool Length Probe, Gantry/Spindle ground connections (or not), and the VGA Cable and Display Monitor, earth and ground connections, would be worth Ten-Thousand words.



Again, Thanks for the Info, and Thanks to The Masso Dev and Documentation Teams for their consideration

Eldonb
 
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lilow

Lilow
eldonb46.

I had a problem in plasma.

I took all power supply DC negatives, all stepper motor bases, all moving parts, gantry, Z axis, etc.

Plus the table positive cable connection, what you would call an earth, connected them all to a common point.

Then I added the same sized cable that was connected to plasma table, from the Plasma machine.

Put them all together and knocked a ground stake outside the building.

Make sure this stake is at least 3 metres from any building power ground stake and goes down deep.

If in a dry climate, a bucket of water on it helps.

There is no need to connect any Masso negatives as you have connected the PS negative.

Cheers.
 
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