Welder Power Supplies

[jclarke4]

Hi,

In an installation there are 6no. Eurarc 420 welders supplied from dedicated 40Amp single phase RCBO's housed within a dedicated distribution baord. The welders can be operated as either single or three phase via a selector switch. The current arrangement is single phase with ABB 32A plug/socket connections. The rated max load in single phase is 93Amps. The users of the welders only use up to 3.25mm electrodes which the manufacturer tells me that using these types of electrodes would only use max of 35Amps.

The RCBO's are 30mA C type and keep tripping out once welding commences. It will be a big job not to mind expensive to change out to hard wired connections via isolators and MCB's so I was proposing to change the RCBO's to D or even K type as the issue may just be in-rush current but I suspect that there may be a problem with earth leakage.

Anybody any thoughts???

John.

 

[itsmoked]

The problem is that a lot of these are giant switching power supplies. Often their required filtering includes a capacitor to earth. This then ships some current off to earth tripping the breakers.

Not sure what you should do to remedy it. Have you talked to the maker? Gotten the leakage current spec for that welder?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jclarke4]

Thanks itsmoked.

I did speak to the manufacturer and he said that 40A Single Phase RCBO's would work but they didn't. I don't have any details on the earth leakage.

The only solution I can see is changing the RCBO's to D Type MCB's but then I will have to remove the plug/sockets and hard wire with isolators to conform to the regulations as portable equipment using plugs/sockets require RCD protection. Also, I am not 100% sure if these units actually can operate from 230Volt single phase. Although the nameplate says 230V/400V, from reading other forums, welders either operate at phase/phase i.e. 400V and not phase/neutral i.e. 230V.
I have attached the welder spec...

 

[richardgb]

I am not an electrician but I have an electric arc welding permit and worked as a welder for about one year in an industrial environment.

Looking at your specs of 35 amps for each welder, my guess is that the starting current might be a lot more than 35 amps, even if only temporary.

The electrode frequently gets stuck on the work creating a short circuit, and the electrode has to be broken of because it stays welded in place. This happens when the electrode metal is naked, without the flux.


What six of these units will do on a single phase supply,
even if individually wired to the board, could be another problem, judging from my own experiences.


Nobody in his right mind would use single phase for six of these. But I am not an electrician. Just talking from plenty of industrial experiences.