Ground fault problem

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Hi Guys,  I seem to have developed a this new problem and I'm not sure how to fix it.  A little background.I have a new Vantage 300 on my rig.  It has about 30 hours on it.  I'm trying to use its 3 phase to run my new Miller XMT-350 inverter welder.  At home (trying everything out) I welded about 10 hours with this setup and it worked perfectly.  The first time I used it (only on one 16" weld) it tripped the GFI on my Vantage on the 120 volt grinder circuit 2 times.  Monday I used this setup again on 3 - 20" welds and it tripped the GFI's on my Vantage 120 volt receptacle (both of them)  every time I struck an arc.  It was even tripping the GFI I wasn't using.Needless to say this is a big disadvantage.    So what in the world could be causing this?The first time it had been raining so I assumed one of my 120 volt plugs must of been wet.  Monday, when it tripped every time I struck an arc,  I had washed my rig the day before, so I suppose some moisture could of been present in the 3 phase plug.  I couldn't see any water anywhere though. If its a ground problem then wouldn't my inverter be grounded through its 4 wire cord?  Its mounted to the same frame that the Vantage is bolted to so I'm assuming its grounded, but I don't have an actual ground wire that I've run.It didn't do it for at least 10 hours before this started, then it only did it twice on that one weld.  Now its every time I struck an arc.This has got me confused to say the least.  I hope you guys can offer me some suggestions to try this weekend to fix this aggravation.  BTW:  When I weld with the Vantage it doesn't do it.  I have yet to trip any GFI with the Vantage, its only happening when I fire up my Miller. lolThanks in advance for your help.Later
Reply:are both machines bolted to the truck bed?   the vantage should have a little lug on on the front for machine grounding.  You might try hooking that to a good ground rod and see if that works.    I run my XMT's off of the three phase plug on my vantage all the time.   but the XMT is usually sitting on the ground not on the truck bed.Vantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.
Reply:Yes, they both are bolted down to the truck.  But with a 4 wire cord I don't see how it matters.  That 4th wire is the chassis ground and even if the XMT were setting on the ground it would be 'grounded' to the Vantage by it.  Right?
Reply:I'd say your Lincoln is rejecting that Miller, isn't that sacrilege to try and mate a Miller to a Lincoln?   Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:A Ground rod does nothing in this scenario- really a Ground rod is only for Lighten Strikes.GFI's do not care one bit about that Rod stuck in to mother earth- they only measure Current coming in and going out- not if a Ground wire is hooked up. They'll work just fine with out a Ground wire.They are sensitive little bastards- as they should be-Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Very funny on the rejection theory, but I don't think thats it. By what I can find out it's not dangerous but a nuisance.  The 3 phase plug is upstream of the 2 - 120v GFI circuits on the auxiliary power supply.  Even with nothing plugged into either of the 2 GFI protected 120v circuits they trip when I start welding with the inverter.  While welding I can reset them and have power to the grinder cord but when I strike the next arc they both trip again.Power surge, noise, conductive ground (?),  voltage drop, or whatever.  Its got me stumped for sure.Judging by the fact it never happened when first rigging it up, then later it happened only 2 times, then now its all the time is making me think the GFIs are being effected by the surge on the 3 phase plug.
Reply:I'd prolly call the LWS where you go it and ask for the local Lincoln reps number and bounce the question off of the rep.The first year or so I had my PowerMig 300 I talked to the rep several times.I'd think Lincoln would take tripping ground faults very serious. A casualty loss suck rocks...Matt
Reply:Your GFI's are connected to one hot lead, and one neutral.Inverter welders (all inverters in general actually) create high amounts of harmonic distortion on their input side (no matter how clean their output is).Because of the nature of three phase wye systems, three phase triplen harmonic distortion (distortion in frequencies that are multiples of three, of the base frequency) travels on the neutral wire (even if there is no single phase current usage).  That's why neutral wires on three phase systems are sized for 150% (or even sometimes 200%) of the circuit current (when you would think that through phase addition, it would be limited to a maximum of 100% of the circuit current, with 0 current on the neutral in a balanced condition).While those currents carry no usable power (which is why they're called imaginary), they are still measurable, and with your Vantage likely bonding neutral to ground, you're probably creating ground faults.  Not dangerous, but possibly enough to trip a GFI.I'm not quite sure what a good solution would be, but removing the ground path between the Miller and the Vantage should stop any neutral and ground currents (forcing a delta connection).  I know that's a no-no with a welder that uses HF.  Not sure about how it would affect your XMT though.The best thing may be to contact Lincoln and Miller, and see if they can dig up some electrical engineer with a better answer.
Reply:Yes rlitman, it is bonded.  And thanks for the reply.  Very informative!!!The GFI modules my new Vantage uses are something new I think.  All the pics I can find must be of older versions of the welder which don't seem to have them.  They use the GFI receptacle type instead.Only an assumption but I'm starting to believe my problem is these new modules.  I think they are more sensitive than the other type.I'm guessing Dualie's machine uses the other type (the GFI receptacles) and not these GFI modules my machine uses, since his miller inverter works without issue.  lolLast edited by slowhand; 11-04-2010 at 06:38 PM.
Reply:Just a thought here Slowhand, but don't the newer Vantages have that Voltage Reduction Device when it's in the CC stick mode. Just wondering if that's what's adding to your problem?
Reply:Have you tried just setting the XMT on the ground and welding with it?Vantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.
Reply:Also note that GFCIs can and do go 'bad'.  As well as being sensitive to pretty small amounts of voltage differentials between the 120V hot and neutral lines (like they are supposed to be).  A little moisture, some HF, an 'iffy' or bad GFCI, or more than one of them could all lead to a tripped GFCI.New machine?  Call Lincoln and have them figure it out and fix it.  The best laid schemes ... Gang oft agley ...
Reply:Does it do it when you run the XMT through the Single Phase 14-50 Receptacle?Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Did some experimenting today and have an update for you guys.BTW:  No, I haven't tried the single phase 50 amp plug.  Only the 3 phase so far.-----------There seems to be a couple more variables to consider than I previously mentioned.  First is my cable routes.  When trying out the new setup at home I had one cable setup, then when I did the "dayview" so to speak, I had the cables rigged differently.  The GFI tripped twice on one weld.  By the next time I tried the rig I had did some cable rigging and had them all very neatly tucked away.  Now it tripped both GFIs every time I struck an arc.  This morning I remembered those facts and actually though it could be nothing but cross-feed by the close location of my power cable and the ground lead.  They were running parallel for at least 6 feet. First I setup the machine as it was when it was tripping on every arc and it held itself true and did trip every single time.  First I moved the ground lead and for a few rods I though I had it fixed, then it did a random trip for no apparent reason.  Next I moved the power cord as far from everything as I could get it, and again I though I had it fixed.  Then once again it did a somewhat random trip.  Then I noticed my scanner antenna.  Long story.That old scanner antenna is a magnet mount and it wasn't wanting to stay where I wanted it too and one day awhile back it fell off and I just tucked it down by the welder.  I now see it was right in front of those nasty GFI modules.  I moved it and once again I though I had found my problem...... then it tripped again.By this time I'm at my wits end so I started trying different settings.  To make it trip right now I had to crank it up to 280 amps - weld a few inches - long arc the heck out of it - rare back and Stick-It while hitting the grinder trigger - and it would trip every time.  Yea the engine would do a groan but after a couple tries I could make it trip like clock-work.At this point in time - my conclusion is - dirty power.  If that is the right answer then I'm not sure how I can fix it. lolI'm not done yet so please keep helping me. okAnd, the VRD only works in CC mode and a way to cut the OCV of the welder down to like 30 volts.  In downhill pipe mode it doesn't work.  To activate it you must hinge down the front panel and flip the VRD toggle switch.  Mine is "off".  I know because I seen it today.The 120 volt GFIs are on the X and Y leads of the auxiliary fields coils.  My miller is using the X, Y, and the Z fields of those same coils.  So this is where I believe the problem is.  lolLater guys.Last edited by slowhand; 11-05-2010 at 04:34 PM.
Reply:Fixed  (or at least it appears to be) Today I tore the bitch down.  My first intent was to just bypass one of the factory GFI modules and put in a  GFI receptacle and try it, but after seeing how hard that would be (machine is on my rig) I decided to just run a jumper out and use an inline GFI instead.  So that was the plan.I needed a good cord about 8' long so off to my junk box I went.  I found an old yellow 12g cord I used like 4 years on my 200d.  What was left of it was about 10' and a good factory female plug.  This should work.I wanted to run it in flexible conduit but didn't have any so instead I used a piece of old 1/2" white water line from my camper.  Its very thick and my cord fits nicely inside.I ran my new jumper through the oil drain hole on the other end of the machine, across the belly pan and through the fan housing bracing.  I wire-tied it best I could.  I split out my leads and ran the black (hot) to the 20A circuit breaker spade on "X" circuit.  There was an extra spade terminal already there and I could reach it easy.  I ran the white (neutral) wire to the neutral grounding lug on the auxiliary panel and the green wire (chassis ground) to the only place I could reach - the chassis ground lug on the tilt down control panel.  By the wiring diagram it has a jumper wire that goes to the auxiliary ground terminal so I felt it was ok to do that.  I just couldn't reach that lug from that side of the machine and the other side was out of the question today.  I'd need to pull the machine to do that.Now my new jumper wire comes out the oil drain hole and back to where my Miller XMT inverter is located.  There I plugged-in a new in-line class A GFI.  I connected my new 125' Miller remote which has a 120v GFI built-into it.  So my new jumper has a 20A breaker and 2 - Class A GFIs so I now feel my helper is safe.  (she's my wife btw) haha-------------  Now on to Testing ------------I find I now can't trip any of my 4 GFIs no matter what I do.  Its now like it should be.  .  I tried everything that worked yesterday but now none of them will trip, even the now unused modules on the front of my Vantage.  I even redressed my cables like they were before (neatly tucked away) and still none of my GFIs would trip.  As far as I can tell after welding with this thing for over an hour - - - Its now finally fixed!!!!!.  ----------I'm not electrical engineer but I can imagine at least 2 different things that might of happened to fix my problem.  #1.  That old 12g jumper cable I used (slightly black on the wires) is somehow acting as a filter and fixed it.   # 2.  The neutral lug wasn't making all that good a contact and by me adding that new neutral wire to it somehow fix that unknown issue.  Either way it seems to be fixed now.  Monday I'll put it to the real test - I'll try it at work on a really tough tie-in weld on a hill side.  hahaThanks for all your help guys.  LaterLast edited by slowhand; 11-06-2010 at 06:42 PM.
Reply:Well that's good news, hope it works! Nothing more aggravating than equipment not working properly.Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400