Reply with QuoteYou should have proper/recommended earth grounding throughout the machine.
Search for equi-potential bonding also.
Do you have some form of shield for the motor conductors? As well as a earth GND to the motor?
Electrical noise? - Need for grounding?
Dear all,
I possess a 6040 Chinese CNC machine run with mach 3.
I tried to install a cheap webcam on the PC controlling the machine to watch the operations remotely.
However, when the spindle begins spinning, I get interference. [Image].
Would properly grounding the machine's chassis help me solve this problem?
Thank you for your help.
PS.
In the past, I have experienced problems with "lost steps" that were solved by reducing the speed, and I couldn't get to work my internet powerline extenders.
Now, only the controller is grounded.
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Last edited by christzerefos; 02-03-2023 at 09:25 AM. Reason: more info
Re: Electrical noise? - Need for grounding?
You should have proper/recommended earth grounding throughout the machine.
Search for equi-potential bonding also.
Do you have some form of shield for the motor conductors? As well as a earth GND to the motor?
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Re: Electrical noise? - Need for grounding?
A:
No.
Proper grounding (you should do) may or may not solve the apparent issue.
The correct solution is to separate webcams etc and all externals from the machine tool controller.
Easy cheap way is a 40$ old pc dedicated to the webcams etc alone.
See 5.xx for solutions ..
Based on 30 years experience, ..
early-on trying to integrate most-all stuff onto pc´s.. including industrial av ..
And dozens of production servers running tens of thousands of clients ..
And later-on as a world-leading cnc (Haas) sales manager overseeing hundreds of installations.
You might do proper grounding, and still have the issue, because some socket, some device (waterheater), creates major emi or ground faults, sometimes intermittently, and even sometimes the ground potentials on different sockets may have high or heavy potential differences, even over 100 V.
1.
2 devices properly grounded in the same locale may have grounds 100V+ apart, and connecting say RS232 serial ports between them will show sparks.
The only practical solution is avoiding the ground-potential issue and avoiding the sparks.
Isolate your stuff, use separate pcs.
Don´t use rs232, use ethernet only.
Fixing the ground-potential issue in a house or industrial installation is sometimes tremendously difficult and extremely expensive.
Often, because the installation may be up to code, properly done, but still have issues.
These may even be related to the neighbours installations - or the power supplier.
2.
Your device or another device might be leaking emi because it does not have a ground or does not share the same ground with the other device.
Often, anything emitting rf or video, may transmit emi that creates ground noise due to emi coupling .
Ground noise is usually harmless.
3.
High loads (industrial cnc) may cause instability in the grid - usually because the electrics provider skimped on "stuff" - because 99/100 of their installations work just fine.
4.
The electrical companies often skimp on very expensive stuff that they are legally and contractually obliged to have before offering services to users.
150.000 € in "stuff" required in their cabinets -- before they are really legally allowed to connect and sell power to consumers.
Happened to me.
5.
Solution.
(If issue persists, ) separate all extras to another pc.
5.1
Ground everything.
5.2
Using pc UPSs, even small, usually eliminates most or all emi.
5.3.
Old (useless) big UPSs that are off-line devices and will eliminate all RFI, EMI, and coupling from and to power lines.
They are somewhat big and quite heavy.
We sometimes sunk extra ground copper poles into the ground in industrial installations.
This is theoretically semi incorrect.
Power grids should not have them, but are allowed "in case of need".
They mostly worked very well.
Re: Electrical noise? - Need for grounding?
What is the spindle specs you are using, once we know what you are using than we can look at what needs to be done what control box do you have as this is where you will have to start, can you post some photos of the inside of the control box as wellOriginally Posted by christzerefos
Mactec54
Screen the webcam cable at cabinet end, keep cable away from any power cables, including drives.
Re: Electrical noise? - Need for grounding?
The answer for me has worked over many decades on installing systems, that is, do not use isolated areas, make everything common to one reference where possible, DO Not use SMPS, use equi-potential Earth bonding practice.
When you mix PC based CNC control with such as HV Plasma tables etc, it is very important.!
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Re: Electrical noise? - Need for grounding?
That will not fix this problem, you have to fix the source of the problem then look at the peripheral devices. these systems are prone to have next to no Grounding in place which has to be corrected for a safety stand point.
Mactec54
Re: Electrical noise? - Need for grounding?
This is the common and correct practice.
Ground everything to one point.
As You said.
In many instances, but only perhaps 2-3%, this does not work for mysterious reasons.
Sinking an extra dedicated ground copper pole near the machine has often solved the issue.
I know, it´s often seen as heresy and near-incorrect, since there should be only one ground point.
In theory.
But electrical codes allow other ground points "where required".
It´s useful to know that I am partly quoting experience from a company that employs 200+ support engineers on staff with 25.000+ machines installed over 30+ years.
And we also had, in my time, a mystery site that had ongoing electrical issues - blowing expensive VFDs at 7000€ each, and or servo amps.
The best techs with all the measurement gear could not identify the source of the errors ! -- true story --
And the mfct kept changing the kit for new, without a solution ..
And I heard similar stories elsewhere in the world -- where some sites were "hard" and new electrical grounds eventually cured the problem.
Previously .. 20+ years ago .. I also personally junked a PC chassis I deemed "cursed".
Changing everything including the PSU would not make it work and last beyond a week or two.
(Motherboard, all hard drives, all cards).
At the end, I gave the customer a new different chassis and PC and the issue went away.
It´s quite possible for a neighbour to have a ground fault issue, or a leak from the power company lines ..
and when they fire up big welders or similar equipment it affects yours, sometimes blowing it up.
But both the neighbours and your wiring and kit may be perfectly up to code, properly installed.
And if the leak is at the power co. they are usually very reluctant to do anything.
Their power co. big kit is very expensive, and 98% of the time it´s the customers stuff.
But 2% of the time, -- it´s not.
Been there, done that, fixed all the issues, usually at great cost in kit, hours, manpower, parts both expensive and cheap.
The answer for me has worked over many decades on installing systems, that is, do not use isolated areas, make everything common to one reference where possible, DO Not use SMPS, use equi-potential Earth bonding practice.
When you mix PC based CNC control with such as HV Plasma tables etc, it is very important.!
