welding adjacent to electronic equipment

[davva]

A specification for some control equipment has a statement "welding within 10m vicinity of control equipment disconnect power otherwise supply filters might be damaged and control system function can be jeopardised."

Is this common? it is fairly important equipment and I have not come across this statement before and could lead to drafting operational restrictions on welding near this equipment.

Is there an emc immunity standard that can be referenced that would offer some protection?

any advise would be gratefully received.

 

[Skogsgurra]

First, gas welding and arc welding usually isn't a problem. TIG and other inert gas welders generate HF interference and that can be a problem over longer distances than 10 m.

There is no cure-all for this. You have to see where cables go. How ground leads are connected and such things. Then try to avoid creating return paths that go close to any part of the electronic equipment or the cables connected to it.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[Comcokid]

Arc welding could be a serious problem as the very-high intermittent DC currents and the long welding cables if the cables end up strung close and parallel to the power lines to the control equipment could induce some nasty low frequency currents directly through magnetic field coupling.

What Skogsgurra is concerned with in his post is E-field interference, which will get into high-impedance circuit points of equipment that is ON and operating. But given that the warning specifically refers to "supply filters", the concern is most likely magnetic field which will couple into very low impedance connections, and into possibly, directly into the magnetic components of the filters themselves. This is probably why they use the word "disconnect" rather than just have you turn-off the control equipment. When you disconnect, the input power filters circuits will be high-impedance with no complete path for currents to circulate.

Given that your discipline is listed as "Marine/Ocean", I can only imagine you are referring to welding going on at the end of very long cables supplied by very high current diesel-motor driven welding supplies.