Mig welder

[Nemises]

Hi guys, I've gone to a job and the customer has a 5-5 split Rccb board, and there shed is wired from a 32amp mcb. But when the welder is in use it trips the RCcb the welder is brand new. What could be the cause?
Cheers

 

[Pete999]

What type of breaker is tripping?

 

[Bobster]

I've got a motor that will not start. Any ideas?

We need quite a bit more information before any sensible answer can be given.

 

[amlu]

get a earth leakage clamp meter and do some tests.

 

[Nemises]

Sorry for the lack of information. It's tripping the 80amp 30mA rccb.

 

[Lucien Nunes]

Is the welder an inverter type or wirewound transformer?

 

[Nemises]

It's a
SIP Autoplus 250ST Mig Welder
I think it's wirewound.
Thanks

 

[Lucien Nunes]

Does the RCD trip as soon as the welder is connected or only when you squeeze the trigger?

 

[Nemises]

He can actually do a bit of the weld before it trips.

 

[snowhead]

Does it trip every time?
What's the current rating (230v) of the MIG?

What's the load on the 80a Rccb that's tripping at the time it trips?

Does it trip after the same amount of time every time?

 

[Lucien Nunes]

Specs a 42A supply but seems to run on 30A, might be much less on thin sheet work. Agree it's not inverter driven. Leakage current measurements would be helpful as no single immediately obvious cause. RCD may already be near threshold.

 

[Nemises]

Yes the rating is 230v. Basically just the welder which is in use in time of tripping. If it's earth leakage, if I run a supplementary earth will this cure? Otherwise I will have to try and do away with being on a rcd.

 

[Nemises]

Just found out its not when it's striking its when he does continues welding

 

[Lucien Nunes]

if I run a supplementary earth will this cure?

I'm not sure why you would think that at all.

The fact that it happens during continuous welding, and that the welder is probably the largest single load, suggests that there may be a neutral-earth fault somewhere in the installation, rather than anything wrong with the welder. If that is the case the RCD would trip with another load of the same size or greater, it just happens that it is only the welder that uses enough current to reveal the problem.

No more guessing, you're going to have to take readings.

 

[Nemises]

Ok thanks for the advice

 

[Nemises]

What readings shall I get? Test the entire board?

 

[Lucien Nunes]

Anything relevant to the RCD that trips. We don't know the nature of the problem at all yet - it could be an N-E fault that is only revealed when the welder load is high enough to drag the N far enough away from earth, it could be a genuine fault in the welder or that the welder has very high leakage by design, it could be that some high leakage equipment is taking the RCD to near its trip threshold even if that other equipment isn't in use. Insulation tests will find wiring faults but if the cause is aggregate suppressor leakage or something else that only occurs with AC or when energised, only a leakage clamp will give you useful data.

 

[PEG]

I would also ask the following;earthing arrangement,cable run distances bench welding,type of socket,how near is board to welding...

 

[bigspark17]

Can you put welder circuit on its own rcbo in the house consumer unit.?