Recurring issues with welders

[Shaneyj]

The welding machines in my shop have had intermittent issues for the last 2.5 years (my tenure at current employer). Different brands, different types, they all eventually quit working, get serviced, quit working again, get serviced again- and the beat goes on.
The shop manager has finally decided to attempt to find the root cause.
I've never worked with power quality analyzing tools.
Any thoughts, ideas, or guidance would be appreciated.
If it is determined that we have power quality issues, is there a component that we can install locally at each welder to clean it up?
Thanks for your input.

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[kwired]

The welding machines in my shop have had intermittent issues for the last 2.5 years (my tenure at current employer). Different brands, different types, they all eventually quit working, get serviced, quit working again, get serviced again- and the beat goes on.
The shop manager has finally decided to attempt to find the root cause.
I've never worked with power quality analyzing tools.
Any thoughts, ideas, or guidance would be appreciated.
If it is determined that we have power quality issues, is there a component that we can install locally at each welder to clean it up?
Thanks for your input.

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It might be a big help to know if they are all failing in similar manner or if failures are seemingly random.

Is it usually same components failing on most of them?

Is duty cycle being exceeded on regular basis?

 

[Shaneyj]

Per our welding servicer, issues are predominantly circuit board related.
He didn't go into detail, just that there have been "board and logic" issues.
Our welders understand duty cycle and they are supposed to stay within constraints. I don't think that is the issue.

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[JFletcher]

Some initial thoughts... Are they being used / abused by the same people? Are these second hand or older machines, or cheaper units that may not last like you want? Do other machines, if applicable, have similar failures?

As for power quality issues, are they single or three phase? Really the only issues you can have at the plug are incorrect voltage which may be a spec error or too much voltage drop on the circuit supplying the receptacle. If you are laying down long thick weld beads with say a 240-volt machine, and you are feeding it with 208v and 500 foot of conductor, then the lower input voltage at the machine could be substantially off of what the name plate requires.

I would start by getting the information off the name plates, or if they are too illegible to read, look up the specs of what voltages the machines require, then go from there to measuring voltage at the receptacle, both with machine off and with machine on its maximum setting. If you had a euro-spec welder designed to run at 400 volts, and you have a 480 volt Services actually putting out closer to 490 or 500 at the plug, well that's pretty easy to figure out. Most welders are pretty tolerant, they even make adapters that can convert a 50 amp plug to a 15 for use on a 15 amp branch circuit.

 

[K8MHZ]

Per our welding servicer, issues are predominantly circuit board related.
He didn't go into detail, just that there have been "board and logic" issues.
Our welders understand duty cycle and they are supposed to stay within constraints. I don't think that is the issue.

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From what I am reading, you have changed everything but the welding servicer, correct? If correct, I would see that as a common denominator.

 

[growler]

Per our welding servicer, issues are predominantly circuit board related.
He didn't go into detail, just that there have been "board and logic" issues.

I don't know about welders but lots of things can effect circuit boards. Heat, vibration, dirt & dust, stray voltage.

I would first consult with the manufacturers and see if they think filtering power to the boards would do any good or if they think that is a possible fault.

I once worked on an industrial type compressor and finally gave up and called the manufacturer's tech rep and he knew right off what the problem was. Wasn't electrical at all but a manufacturing defect and the correction was simple.

My opinion is that no one knows more about a piece of equipment than the people that designed and built it. Not that they are always helpful but sometimes they are.

 

[Shaneyj]

Some initial thoughts... Are they being used / abused by the same people? Are these second hand or older machines, or cheaper units that may not last like you want? Do other machines, if applicable, have similar failures?

As for power quality issues, are they single or three phase? Really the only issues you can have at the plug are incorrect voltage which may be a spec error or too much voltage drop on the circuit supplying the receptacle. If you are laying down long thick weld beads with say a 240-volt machine, and you are feeding it with 208v and 500 foot of conductor, then the lower input voltage at the machine could be substantially off of what the name plate requires.

I would start by getting the information off the name plates, or if they are too illegible to read, look up the specs of what voltages the machines require, then go from there to measuring voltage at the receptacle, both with machine off and with machine on its maximum setting. If you had a euro-spec welder designed to run at 400 volts, and you have a 480 volt Services actually putting out closer to 490 or 500 at the plug, well that's pretty easy to figure out. Most welders are pretty tolerant, they even make adapters that can convert a 50 amp plug to a 15 for use on a 15 amp branch circuit.

480v machines. They don't discriminate with regards to the user.
Service seems stiff.
Morning voltage around 289 to ground and 490 phase to phase.
Afternoon never seen less than 278 to ground or 480 phase to phase.
Some of the issues revealed with older machines (4-5 years daily use), but also with machines less than a week old.
Most recently is 2 Miller tigs fresh out of the box.

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[Shaneyj]

From what I am reading, you have changed everything but the welding servicer, correct? If correct, I would see that as a common denominator.

Correct. The other common denominator is power supply to machines- ours.

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[Shaneyj]

I don't know about welders but lots of things can effect circuit boards. Heat, vibration, dirt & dust, stray voltage.

I would first consult with the manufacturers and see if they think filtering power to the boards would do any good or if they think that is a possible fault.

I once worked on an industrial type compressor and finally gave up and called the manufacturer's tech rep and he knew right off what the problem was. Wasn't electrical at all but a manufacturing defect and the correction was simple.

My opinion is that no one knows more about a piece of equipment than the people that designed and built it. Not that they are always helpful but sometimes they are.

Good point. I've yet to call manufacturers, but will make it a point to do so.
FYI, these are Lincoln and Miller migs and tigs.
On another note, our plasma torches have had zero issues.

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[kwired]

Per our welding servicer, issues are predominantly circuit board related.
He didn't go into detail, just that there have been "board and logic" issues.
Our welders understand duty cycle and they are supposed to stay within constraints. I don't think that is the issue.

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Knowing the details of what is failing on those boards could be useful for finding the cause. Could be power supply issues, could be user issues, could be bad equipment design or even combinations of those things.

 

[drcampbell]

What's the temperature, humidity and airborne dirt level in your shop? I see you're in south Texas, maybe your circuit boards need more airflow—bigger fans & filters, or more-frequent filter cleaning.

 

[Shaneyj]

What's the temperature, humidity and airborne dirt level in your shop? I see you're in south Texas, maybe your circuit boards need more airflow—bigger fans & filters, or more-frequent filter cleaning.

Dirt/ dust level: high
Temperature: always hot (Houston)
Humidity: air consistency about the equivalent of yogurt
These issues are year round though. Even in milder winter climates.

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[FionaZuppa]

Hobarts(ITW) and Lincoln's?

Are the TIG units inverters or transformers?

Are they welding DC or AC or both?

Try introducing a ESAB or Everlast unit to the mix, see if the problem reaches across to these other makers.

Perhaps also scope the EGC of the ckt's while welding is in use to see if there are any odd harmonics on them. harmonics could (could) cause havoc to other equipment

 

[Shaneyj]

Hobarts(ITW) and Lincoln's?

Are the TIG units inverters or transformers?

Are they welding DC or AC or both?

Try introducing a ESAB or Everlast unit to the mix, see if the problem reaches across to these other makers.

Perhaps also scope the EGC of the ckt's while welding is in use to see if there are any odd harmonics on them. harmonics could (could) cause havoc to other equipment

Miller's and Lincoln's.
Tigs are inverter.
Not sure AC or DC.
I've heard that high frequency harmonics can destroy circuit boards, and these frequencies can be injected from one machine to a other via ground.
Our welders ground to their respective pieces while welding. No common ground point from one work piece to the next.

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[FionaZuppa]

Miller's and Lincoln's.
Tigs are inverter.
Not sure AC or DC.
I've heard that high frequency harmonics can destroy circuit boards, and these frequencies can be injected from one machine to a other via ground.
Our welders ground to their respective pieces while welding. No common ground point from one work piece to the next.

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You might try adding an inline inductor to the EGC near/at the receptacle that each machine uses. Or use a hefty ferrite ring wrapped many times with appropriate sized wire. If it's hard wired gear then its a tad more of a challenge.

Perhaps ground loop (common mode) currents are being generated when certain combo of gear is being used at the same time.

I would attempt to find ground loop currents on egc, and, scope the egc with FFT function to see what harmonics are being produced.

MIG and TIG are all sorts of noisy due to arc and frequency overlay. How are the TIG units being used, DCEN or DCEP ?? Are the pieces being welded on a table? Many times metal tables are "connected" to egc via GES as the metal tables are tied into the concrete floor. Using isolation pads may help if tables are being used. Heavy metal parts just on the concrete floor can also make the connection, so even using a welding blanket under the metal parts can help keep it isolated from the concrete (or some other form of isolation pad).


see https://www.aticourses.com/sampler/IntroductionToEMI_CourseSamplerR.pdf
and http://web.mit.edu/jhawk/tmp/p/EST016_Ground_Loops_handout.pdf