External EMI filter for MIG welder?

[fubar.gr]

I have a MIG inverter welder, and when it is in use, the fluorescent tube lights will flicker and one of the computer UPS goes rapidly into and out of overvoltage protection, making its relays chatter.

I suppose this is due to insufficient EMI filtering on the welder. So far I haven't noticed any other problem, but I don't feel comfortable with all that noise on my wiring.

Is there some type of external EMI filter that I could use on the welder? Like something that goes between the wall socket and the welder power cord?

[SeanB]

More likely the supply is on the same outlet, and this has poor connections. Use the welder on a different circuit, and if this does not cause interference then you need to check the circuit the lights and UPS is plugged into. There likely is a poor socket ( very likely with the Attic socket system, it easily loses tension in the sockets from age, use and overloads) on the supply, or the supply itself has high impedance connections there.  As you do live in a complex it likely is they skimped on cable size, and it might be poorly sized to run the 16A load of the MIG welder or the connections to the breakers might be loose or arcing.  time to call an electrician to inspect the system, and verify it is still compliant with regulations.

[Kleinstein]

Arc welding is notorious for poor EMI. If you choose EMI filtering, take into account that they often stretch the limit of the fuses up to the limits, so even if meant to be used on a 16 A fuse, they might well use up to 20 or 25 A, because the fused will tolerate it for 1 minute or so. So prefer filters made for 20-25 A or so. For the same reason make sure the outlet is connected with good size wiring (e.g. 2.5 mm², not 1,5 mm²).

Sometimes with a longer distance to the distribution transformer, the grid voltage might just drop to much because resistance is to high. Here a filter can not help as the problem is at 50Hz not in the kHz range.