Grounding and Noise

[SCHIDTHEAD]

I have recently moved my table from a shop with a conductive ground that took a while to condition and establish with one 8' rod, but once established,the set up ran flawlessly for 4 years.

Knowing what I had to go through the first time around with an earth ground, I should have looked at the soil around our new shop...but it is what it is and we are where we are and it never crossed my mind before moving on top of a sand box>>>kick myself...

Symptoms: We set up the system and started with a 8' rod near the table through the slab. Cut some test cuts and one larger file all went fine for a couple of days...then the ghosts started to show up. Glitches in the start/wait, pierces and no travel, stops in the middle of a cut...The machine runs without a flaw with the torch off; once turned on and fires, it pierces and doesn't travel, but progressively gets worse as if either RF or voltage is building in the table...I just can't figure out which one.

Did the lightbulb test for our ground resistance and found we were at nearly 2 volts; since then, we have installed 4 ground rods 10+ feet apart, with one stacked and welded and driven to 65' and soaked the rods which drank it up. This has brought our voltage reading down to .7V and our symptoms got worse.
Contacted Lyncole XIT Grounding in CA and they suggested to tie the earth gounding into the service bus bar and re-route all grounding to there. Done, and still no changes. They said all we have done should be a little overkill, but they could have someone out to test noise and resistance and remedy for $3200. He blames the symptoms on RF noise building in the table, where, I dont see RF in the glitches which I have seen and remedied in the past; I am leaning toward a voltage build up-- thinking we are still not properly grounded.--I know the lightbulb testing is not an accurate test, but it has worked for me in the past.
We have separated and spread out insulated control wires, the work lead out of the cable chains, moved and positioned and repositioned the torch in relationship to the computer and controller. The machine set up and floor configuration has not changed but by a few feet from the old shop, and we have even moved the Hypertherm further away from the control/comp. All wiring is shielded.

Any grounding or RF shielding suggestions or input would be greatly appreciated before dropping 32 bigguns to remedy this. Anybody need to take any extreme measures to acheive a good ground and how?

Thanks, and have a gr8 weekend everyone!
Steevo out!

[CNCCAJUN]

http://ecmweb.com/content/achieving-acc ... -poor-soil

Looks like some helpful info . . .

Steve

[jimcolt]

I don't know what brand and model cnc machine you are using....that may help. It is possible that the noise issue is coming back through the AC powerline. My tables both have the PC and all of the machine drive and electonics (all 120 volt) being fed through a good quality UPS (from an office supply store) that has noise filtering on the 120 volt outlets. When I installed my 4 x 4 PlasmaCam about 8 years ago I had similar issues as yours....the ground rod (one, 6" from the machine) made the issues about 50% better, the UPS solved them 100%.

You could be picking up noise from a different AC circuit...or from simply a different routing of the AC wiring. The noisemakers on the machine are: The plasma power supply......it is a pulse width modulated unit operating at about 70kHZ.....some of this noise can couple through cables....where (if the cables are shielded and grounded only on the end nearest the earth ground) it should naturally find its way back to ground. Some of the noise can get back into the inlet AC power for the plasma.....which, through the panel can find its way into the 120 volt AC lines as well. The other noisemaker would be the drives....(don't know what machine you have....whether steppers or servos), which also use pulsewidth modulation to control the number of steps or the speed.

Jim Colt

[SCHIDTHEAD]

I am runnning a ShopSabre power supply on a Dell PC with WinCNC controller using Sanyo stepper motors wth a Hyperthermonuclear 1100 with a RT80M. We have run the unit to a separate 20 amp circuit. Off to research and find a good UPS to try. Thanks Jim and Steve.

[Shane Warnick]

I second the UPS. I had a few ghosts when I first installed my machine, good grounds etc. Had all the grounding verified by some electricians I know that do that for a living, also have a buddy that does cathodic protection come out and check around, they all swore that it wasn't a ground issue, said it was a power issue coming in from the main. Bought a good UPS, not a single issue since. The way they explained it to me was that things like an add a phase, used in a shop near you, can feed back and send some funky junky your way. Also, if there are any big shops near you, or you are using some big 3 phase motors you could have a power factor issue. The really big motors stretch the sine waves out and reduce the power factor in the actual power, and when they are coming on and off they can affect the power for quite a ways. So much so that the power company actually charges customers who do this extra, and they make capacitor kits for power factor correction etc but they still send some funky junky down the line. Same thing can happen with 2 phase motors that are at or near max capacity running 240v. Just a thought. Anyways, a good UPS with a battery backup will condition the power and remove a lot of the trash in the power. Seems like overkill, but when you realize that you are dealing with a table that has a constant feedback loop, that is dealing with microvoltage and must be very fast to respond and keep up, you can kind of see where some issues could arise.
Good luck and let us know what actually fixes it.
Shane

[m79b01]

How big of a UPS is required? I have a power conditioner that is rated at 3.0 Amps. Would that be big enough? Do you run the UPS for both the computer (Mach controller) and the table (candCNC) or just one or the other?

[Shane Warnick]

I don't know what mine is rated at, I bought it at best buy when I bought the computer. Plugged my computer and the table into it, the torch is obviously 240v so it has it's own plug. Has a battery and says it will run up to 6 devices for 8 hrs if the power should go away. All I know for sure is that the twitchy issues went away when I started using it.
Shane

[CNCCAJUN]

I don't know what mine is rated at, I bought it at best buy when I bought the computer. Plugged my computer and the table into it, the torch is obviously 240v so it has it's own plug. Has a battery and says it will run up to 6 devices for 8 hrs if the power should go away. All I know for sure is that the twitchy issues went away when I started using it.
Shane

Any chance you could share make & model since you have something that has proven to work. 6 devices for 8 hours has to be a fairly large UPS.

Steve

[Shane Warnick]

Its really not that big I just remember that 6 devices for 8 hours deal because we were making fun of the salesman at best buy. I think he must have said that 15 times in 2 minutes. I won't deny that it will do that, but it wouldnt be a tv, a DVD player, the satellite, the wii, my laptop, and the table for 6 hrs. Might charge a phone or 4. It will keep that table and the computer running for 1 hr that I know, I unplugged it just to see. Got bored after an hour plugged it back in. I will grab the info and post it and a pic when I go back to the shop tomorrow.
Shane

[CNCCAJUN]

Its really not that big I just remember that 6 devices for 8 hours deal because we were making fun of the salesman at best buy. I think he must have said that 15 times in 2 minutes. I won't deny that it will do that, but it wouldnt be a tv, a DVD player, the satellite, the wii, my laptop, and the table for 6 hrs. Might charge a phone or 4. It will keep that table and the computer running for 1 hr that I know, I unplugged it just to see. Got bored after an hour plugged it back in. I will grab the info and post it and a pic when I go back to the shop tomorrow.
Shane

Sounds like all us plasma guys need . . .

Thanks,
Steve

[jimcolt]

You have to look at the specifications on the data tag on your computer as well as your drive and electronics boxes....look for wattage ratings. If the computer says it uses 150 watts and your drive electronics require 200 watts, add them together and you get 350 watts. To safely size a UPS I recommend getting one that can handle 2x (or more) of the required power of everything you plug into it. Some UPS are rated with wattage, some are rated with VA (which is close enough to the same number as wattage). So, for a UPS for the above calculated 350 watts...I would shop for one that can handle around 700 watts. A little smaller will work, bigger is always better.

My machine computer stays on continuously....has been on for 4 years. Power outages occur....and my computer never has had to shut down as the UPS keeps it on. Thunder storms have occured, brownouts have occured...no issues whatsoever. That is what a UPS id designed for....and it definitely helps to isolate from electrical noise that may be produced by a plasma, by the machine drives, or by other equipment in your shop.

Jim Colt Hypertherm

How big of a UPS is required? I have a power conditioner that is rated at 3.0 Amps. Would that be big enough? Do you run the UPS for both the computer (Mach controller) and the table (candCNC) or just one or the other?

[Shane Warnick]

Steve,

Sorry I forgot to get the info off the UPS today. Yesterday way a Monday from hell, today was yesterday squared. I will try to get the info and post it tomorrow while I am at the machine.

Shane

[drakus]

2x the power requirements is a normal rule of thumb. If you can afford to spend a few bucks more, go with 3x, it will condition your lines a lot better. Also, some devices do not like to be plugged into the battery back up plugs, so you may want to plug them into one of the normal slots, don't worry, it will still get the line conditioning, just wont run on the battery back.

Also, I would call an electrician and have him check your power lines and also the breaker box for potential problems.

[_Ogre]

with one stacked and welded and driven to 65' and soaked the rods which drank it up.

holy smoley! what planet do you live on?

we get mud when we drill anchor bolts.
currently there is water on top of the floor in one corner of the shop.
94 inches of snow melting hasn't helped...

can't suggest anything, try the ups
this is the way we tied everything together, i believe i read my 'how to' in a jim colt post

ground buss welded to table leg with #6 bare to everything


lug welded to table, work clamp to it

[Shane Warnick]

here is my current setup

[m79b01]

I "think" I may have solved some of the ghost issues that I was having with a power conditioner also. I currently have a powervar 3.0 hooked up on the CandCNC Bladerunner box and just cut approximately 900 inches on 14ga. All was cut with finecut some at the slow speed settings and some at the standard. This should not seem like a big deal, however this is the most cutting that I have been able to do at one sitting without having some sort of issues. No loss of arc!!!! Thank you all for the info. I may never have come up with this on my own.

[ColoradoWayne]

I know I'm getting in here a little late, but if I understand everything I've read in this thread it may apply to me too? I have just installed a LDR 4x4 w/water table and a PowerMax 65. After a couple self-imposed problems I managed to cut my first piece - proud owner of a 4 inch square with a real nice circle cut out of the middle.
However, when I went back the next day (after a nice little thunder storm rolled through) I got no joy. Torch fires, nothing moves, the torch goes out, air blows for a minute and then it just sits. Repeated this with a couple different things to cut. If I turn the torch and THC off the table runs through the entire process without error. I live in Colorado and it is a new service to the shop with two nice grounding rods - but it is all sand!
Does this sound like the "ghosts" I read about? Is a UPS in my future? This is all very new to me and I have a buddy driving several hours next weekend to come teach me whatever an old dog can pick up. I would like the table to be flawless when he gets here.

Thanks for your guidance
Wayne

[m79b01]

Sounds a little more extreme than I had but sure fixed my problems. I have about 2% of the problems that I had before the powerconditioner. Now it is small tweaks not "this worked once and now it doesn't".

P.S. I am also in sand. Put my ground rod in 10 ft by hand(i.e. not even a hammer just pushed it in next to the shed)!!!!

[ColoradoWayne]

If it has helped you and several others it is probably the right thing to do, regardless if it fixes everything or not. I was looking at Best Buy on-line and I see they have UPS systems and surge protectors. If it is really noise elimination that helps, I am wondering if it would work better to maximize the joule rating and noise filtering? Right now I have all my wires on the floor in a heap too, probably getting things cleaned up and separated may help too. I am just confused because it worked one day and then it didn't work the next day.

They have a surge protector for $39.99 that seems to have pretty high numbers:
4350-joule rating - Absorbs a high amount of energy to adequately protect and help prolong the life of your equipment.
12 surge-protected outlets
58dB maximum noise filtering - Helps minimize interference for reliable performance.
LED indicators - Show you the surge and ground status at a glance.

[weldor2005]

If it has helped you and several others it is probably the right thing to do, regardless if it fixes everything or not. I was looking at Best Buy on-line and I see they have UPS systems and surge protectors. If it is really noise elimination that helps, I am wondering if it would work better to maximize the joule rating and noise filtering? Right now I have all my wires on the floor in a heap too, probably getting things cleaned up and separated may help too. I am just confused because it worked one day and then it didn't work the next day.

They have a surge protector for $39.99 that seems to have pretty high numbers:
4350-joule rating - Absorbs a high amount of energy to adequately protect and help prolong the life of your equipment.
12 surge-protected outlets
58dB maximum noise filtering - Helps minimize interference for reliable performance.
LED indicators - Show you the surge and ground status at a glance.

Just FYI, Most if not all UPS are surge protectors too, but what you described as a surge protector is not a UPS.

[tnbndr]

Do all UPS/Surge Protectors have line conditioners? Most I have looked up say nothing about that.

[Shane Warnick]

I know I'm getting in here a little late, but if I understand everything I've read in this thread it may apply to me too? I have just installed a LDR 4x4 w/water table and a PowerMax 65. After a couple self-imposed problems I managed to cut my first piece - proud owner of a 4 inch square with a real nice circle cut out of the middle.
However, when I went back the next day (after a nice little thunder storm rolled through) I got no joy. Torch fires, nothing moves, the torch goes out, air blows for a minute and then it just sits. Repeated this with a couple different things to cut. If I turn the torch and THC off the table runs through the entire process without error. I live in Colorado and it is a new service to the shop with two nice grounding rods - but it is all sand!
Does this sound like the "ghosts" I read about? Is a UPS in my future? This is all very new to me and I have a buddy driving several hours next weekend to come teach me whatever an old dog can pick up. I would like the table to be flawless when he gets here.

Thanks for your guidance
Wayne

I don't know what software you are running, but this almost seems to me like the software is never getting the arc ok signal back from the torch so it never starts moving, as it doesn't know that a stable arc has been achieved. In short, it thinks the torch never fired and so never moves the gantry. That is probably why it works when you turn off the torch and THC as it knows they are not being used and you are just running a sim so it doesn't need to wait for the signal. Hard to say for sure but you could have inadvertantly changed a setting somewhere and not even realized it. Double and triple check them and then see what you can make happen.

Shane

[dhelfter]

Wayne, I sent an email explaining how to check the arc ok signal. If you need assistance please give me a call. I really doubt it is noise, I believe you are not getting a signal back for arc ok so no motion is happening, then the plasma times out and extinguishes the arc. Could be noise, but really doubt it. Again if problem persists please call.
Thanks
Dan
315-328-4315 shop
315-244-9669 cell

[ColoradoWayne]

You guys are exactly right. I did the check Dan directed and the equipment is spot on. I may have clicked something I should not have, but heaven only knows. We did confirm, with Dan's help, that my set-up for basics like pierce time and cut speeds are way off. Back to the drawing board for me. BUT - on the good side I did get a very nice surge protector from Best Buy with a very high surge protection and RF control rating - $40 can buy a lot of peace of mind with the number of thunderstorms we have around here. Thanks everyone for your help. I am checking out as I believe we've isolated that grounding and noise are not my problem. I think it is the loose nut behind the keyboard.

Thanks,
Wayne

PS - Quick update. I corrected tool settings and everything worked perfectly tonight! Wooohoooo!