Idle thought raises query.

[Debs.]

Possibly a daft question, but here goes:

When working multi-process` on a metal welding-table; does it risk damage to the electronic/inverter based machines by leaving just their work clamps attached (with those machines switched off) to the table at the same time when using MMA?......or, would it be better to remove the clamps of Plasma/TIG/MIG units from the table when not using each process?.....I was thinking about 'stray' currents.

 

[shenion]

My MIG, TIG and Plasma machines are all tied together or clamped to the bench. However, all 3 of mine have no electronics.

In theory, when you break a DC MMA arc the voltage goes toward infinity due to the reactor. Could arc to anything (mine will maintain over a 1" arc if you pull the rod away slowly.) So could arc to case, through supply grounds then through another machine to get to the common return lead.

Good idea to disconnect and I have seen it recommended in at least one user manual (TIG with HF start.) Probably a rare problem but still better to be sure.

 

[scarecrow]

excellent question Debs but I'm afraid I don't know the answer under the theory of what comes out go back in the same way as the on and off switch only isolates the input to machine

 

[tigler]

Damage is *HIGHLY* unlikely but not impossible. The process by which it could remotely happen is by stray induced fields from inductor exitation or EHT radiation.

 

[oilcooled :)]

just want to add a bit more two it, can i have my 2 oil cooled arc welders earthed to the one bench and run the two off them at the same time, or is that dangerous,

 

[tigler]

I would say not. No electronics to be damaged. Also , they are effectively isolation transformers.

 

[pidgeon chit welder]

I would say not. No electronics to be damaged. Also , they are effectively isolation transformers.

I would say the opposite ( awkward B are'nt I? ) If there is any leakage Debs as you say Mr Eddie Currents & his friends could cause you great damage to your elecronics.

During my electronics apprenticeship as a Radar Technician I was alway taught to tie any unused ends to an earth to stop spurious eddie currents and induced currents affecting circuit boards elsewhere.

For the sake of either unclipping or getting a true ground bonded earth to the bench it is not worth the risk of leaving them there all together.

 

[tigler]

I would say the opposite ( awkward B are'nt I? )

Yes

I was answering the Q on oil cooled arc welders.
But , with my previous answer I was pointing the same finger as you , it is only remotely possible though with the potentials involved in welding secondary circuits.

 

[Debs.]

I would say the opposite ( awkward B are'nt I? ) If there is any leakage Debs as you say Mr Eddie Currents & his friends could cause you great damage to your elecronics.

During my electronics apprenticeship as a Radar Technician I was alway taught to tie any unused ends to an earth to stop spurious eddie currents and induced currents affecting circuit boards elsewhere.

For the sake of either unclipping or getting a true ground bonded earth to the bench it is not worth the risk of leaving them there all together.

I must admit that pidgy`s comments seem to chime with my gut feelings....e.g: `thinking about the trouble that 'ground-loops' can cause in audio/video systems and having a variety of AC and DC high current devices effectively sharing a connected/common return clamp and a common mains supply, seems like asking for trouble....although I agree it`s (probably) less-so where isolation is provided (effectively) by a transformer.

I will be de-clamping equipment from the bench when it`s not in use from now on.

 

[Weldingartisan]

Well I don't know the do's and don'ts of it, but I do and haven't suffered any damage yet. As to paralleling two transformers you would have to connect the rod holder ends together as well as the earths to get double the current. W/A

 

[Robotstar5]

Just to add to the fun, we have 6 machines at work where two robots quite happily weld the same component at the same time with seperate weldsets and no problems!