Welder tripping circuit breaker at high setting

[ABBEY]

Hi All.
hoping someone can help. I have a 3 phase FRO system-mig 400 mig welder.

It has 6 course settings and 6 fine settings. when i turn the course setting up to 6 it keeps blowing the circuit breaker. i have used other sized plants on this circuit breaker and its fine and have used the machine on different breakers and it keeps blowing them. So i'm thinking it must be the machine

i have cleaned the contacts on the contactor and have removed the rectifier from the machine and it is still tripping. All that remains are the two power switchs ( huge amount of wires) and the transformer.

Do transformers normally give trouble??

thanks

 

[Luke]

Transformers are inductive, depending on the curve on the breaker, the in-rush will trip it. Ideally, you want a D curve, but a C may well be ok. A standard B curve is likely to trip with an inductive load.

 

[ABBEY]

Transformers are inductive, depending on the curve on the breaker, the in-rush will trip it. Ideally, you want a D curve, but a C may well be ok. A standard B curve is likely to trip with an inductive load.

Thanks for the reply. It is a C class breaker and its a 20amp fuse/breaker.Will i change it to a D class? i'm nearly positive its the welder.

 

[Luke]

The insulation on the transformer winding may have failed. Have you tested for a short circuit to earth?

 

[mike 109444]

What does it do on one down from max (5!)

 

[ABBEY]

i have checked it with a multi meter and using an insulation tester and it looks fine.

on the course setting down one notch it is tripping but not as frequent.

there are 36 settings (6x6) and it goes from 15.7v to 29.7v ( diagram on the front of the welder) . Any setting above 24v is tripping the 20amp C class circuit breaker. I have now removed the two power selector switches and found out that there is a place locally that builds them. I might send the switchs to them and see are they ok. Other than that i'm only left with the transformer. Can they be replaced/ rewound?

Ive removed the wire feed motor and rectifier so there is not much left in the circuit

thanks for all the help

 

[piman]

Hello Abbey,

if it doesn't trip on lower settings then that indicates the machine is OK. What is the KVA rating and or the input current rating from the name plate?

Alec

 

[tlovatt]

Does the supply trip as soon as you select the top setting, or is it when you try and weld

You need to look at the rating plate on the machine, but I would expect a 32A 3 phase supply assuming the 400 in the name standds for a 400A MIG unit?

 

[AndyStobbs]

400A is a big ask from a 20A supply

 

[tlovatt]

On the positive side, if it is a 400A mig unit we can confirm that your 20A breaker appears to be working ok !!!

 

[Jim Davey]

The machine is very likely 100% ok, 400 amp output on a 20 amp breaker is not likely to work. Putting it on a D type breaker may not be the answer. Post up a picture of the rating plate on the machine (if it's legible/present) and I'll advise you on it's pwer supply requirements.
DON'T JUST UPRATE THE FUSE/BREAKER, it was specified for a reason by whoever installed the cabling for your premises and fitting a larger one may lead to melted wiring, voiding your insurance and a fire etc.
Ensure you seek advise from a qualified electrician with experience of industrial equipment and its requirements before you attempt to alter the supply circuit.

 

[ABBEY]

Firstly, thanks everyone for the help

i will have a look at the input plate again to see can i make out the rating. It was difficult to see it today. The machine has always worked on a 16Amp 3 phase plug and only started giving trouble last week.

Having it turned up to roughly 95%, not welding any thing, it trips if i switch on the contactor repeatadly 3-4 times. At 80% it trips after 7-8 times. At 100% it trips after 1-2 times

i'm not welding anything and even have the wire feed motor unplugged

 

[ABBEY]

I looked at the plate and this is what i can make out