old stick welding m/c

[Gerbilsquasher]

+1 on D curve circuit breaker

I'm no expert, but I have been here before. Changed breaker from a 20 amp C curve to 25 amp D curve and it has drastically reduced most (but not all!) of the annoying breaker trips when you first turn the welder on. This mostly occurs with my transformer Transtig 275 which is essentially a big single phase welder running on the 415V between two phases. OTOH I also have a true 3 phase mig welder with a higher current demand that never trips the 25 amp D curve breaker- something to be said about loads balanced across all 3 legs? Do even D curve breakers trip at inrush current on only two legs? Maybe a question for the boffins....

My sparky at the time (who has now proven himself to be complete tool) was reluctant to go bigger than a 25 amp D curve breaker because he reckoned he was trying to save me money. Nothing to do with the cabling- I ran 6mm cable to all outlets when he said I could 'get away with' 2.5mm. Next time, I'll go bigger than 25 amp.

D curve (or 'motor start' breakers) are designed to handle heavy inrush currents for a little bit longer. Get as high a current rating as your cabling can handle- the extra dollars you spend now will be paid back in no time through reduced frustration.

Also, on cabling size: I'm not sure about the mathematics (I could Google this) but cabling which is too small will have increased resistance under load thus requiring more amps to push the same amount through, which might be contributing to your problem. Also the long run you mentioned (80m) might also be a factor if the cabling is too small. There might be a voltage drop under load- as voltage decreases current increases.

Don't dig it up until you have eliminated all other variables

Maybe you can plug in the welder at the non-shed end and see if it trips the breaker there?

[gpigeon]

I still haven't got around to moving the m/c back to the old shed nor checking kA ratings of the breakers.............BUT, after reading the Hager tech bulletin on MCB's regarding inrush current to transformers, I think that this will be the problem. I have not matched the devices and have the wrong "curve' fitted.

I have however got my second welding m/c up and running without problems in the new shed. It is a Transtig 180.

Can anyone advise if there is a problem using the Transtig 180 as a normal "stick" welder?

Thanks for the help rec'd. so far.
Rgds.
Bill.

[Gerbilsquasher]

Can anyone advise if there is a problem using the Transtig 180 as a normal "stick" welder?

My Transtig 275 work great as a stick welder, I think all Transtigs were designed this way. However, if I am not Tig welding I usually get lazy and just use the Mig. I know I should practice my stick welding

[Chas]

If your moving the welder back to the old shed does not eliminate the problem, you might consider posting some photos of the welder and a close-up of the connector block. Someone might recognise what you have and be able to offer more help.

Chas.

[Chas]

I have an old unknown brand stick welder which has worked for many many years without a problem. The other day I moved it to a new shed and when I switched it on it dropped out a 30A breaker.
I have checked the line conns to the plug (4 pin - 3 ph + E) and socket and they are correct. The m/c was running on 2 phase. That is line to line - NO neutral. (checked at 457V)

The machine terminal block has 3 pairs of 2 conns.
The first pair is "hand" marked 240, the second pair is marked 480 and the third is 415. There are 2 copper link bars supplied.

Line 1 and Line 2 conductors are connected to the 240V terminals and both copper link bars were across the 415 terminal screws. The 480V terminal screws were unconnected.
Has anyone got a machine with a similar setup with an "original" connection diagram? (as opposed to my hand written one) If so, does the above connection appear correct
I realise this is "sparky" territory but I am one for trying to work out things for myself first!!!!!
Any suggestions as to why the unit is now dropping the breaker out?
Thanks.
BW.

Hello Bill,

After considering the information in your post, I have put together a diagram of the probable configeration of your primary connections. You would need to verify by removing all jumpers and metering the coils. It is possible that the manufacturer may have :
a) Only tapped one coil at a 175v point instead of both at 208v for the 415v option. In that case Terminals #5 and #3 will be common.
b) Terminals #3 and #6 might be reversed from the diagram I have drawn. In that case read #6 for #3 in para a)
c) In view of your measured supply voltage of 457v, you might consider the 448v connection option shown below the 415v connection diagram. This will work ONLY if both primary coils are tapped. If you have the situation in para b) then for 448v the jumper would need to connect #5 to #3, not #6. In that case, the links provided will probably not reach, requiring a made-up jumper.

I hope this information is of some use to you.

Chas.

[gpigeon]

Chas,
Thanks very much for the diagram. That was exactly what I was after. I presently have the machine completely pulled apart for a general service. Minor rust in the steel cabinet, cleaning dust out, etc., so it is a good opportunity to meter the coils as you suggested.
I still have not moved the machine back to the old shed because even with the cabinet off it is one heavy "mother" and is just beyond my "safe" lifting limit (maybe 60kg+). I originally moved it on a carryall on a tractor but the current wet weather is dampening my enthusiasm to repeat the effort.
However, I should get the chance to meter the windings today as you have suggested.
Thanks again.
Bill.

[brightspark50]

Is the new shed a new electrical installation, if so RCD`s will be fitted to the power outlets older machines tend to have higher earth leakage which could be causing the trips

[gpigeon]

Finally got back to this job.....
The MCB in the new shed is a Merlin Gerin 3 pole C32N 6KA 16A. So, this translates to a "C" curve 16A breaker.
From what I gather I should have a "D" curve 20A MCB fitted. As some of you have recommended!!!!!

I also had a look at the windings. Chas, they are different what you suggested and I will attempt to att a schematic.
With ref to that schematic (if it works) L1 & L2 go to terminals 1 & 4.
Terminals 3 & 6 are handmarked 415 and terminals 2 & 5 are marked 480. This kind of makes sense because if the links are across 3 & 6 (415V) , all four windings are in use. If the links are across 2 & 5 (480V), only two of the windings are used.

Rgds.
Bill.

[Chas]

Finally got back to this job.....
The MCB in the new shed is a Merlin Gerin 3 pole C32N 6KA 16A. So, this translates to a "C" curve 16A breaker.
From what I gather I should have a "D" curve 20A MCB fitted. As some of you have recommended!!!!!

I also had a look at the windings. Chas, they are different what you suggested and I will attempt to att a schematic.
With ref to that schematic (if it works) L1 & L2 go to terminals 1 & 4.
Terminals 3 & 6 are handmarked 415 and terminals 2 & 5 are marked 480. This kind of makes sense because if the links are across 3 & 6 (415V) , all four windings are in use. If the links are across 2 & 5 (480V), only two of the windings are used.

Rgds.
Bill.

Hello Bill,

I beg to differ on part ot the above; according to my reading of your schematic, if the links are across 3 & 6 (415v) then only two of the windings are in series, they are the 208v windings giving 415v. If the links are across 2 & 5 (408v), all four windings are in series, giving 208v + 32v + 32v + 208v = 480v. If you connect a link between 1 & 2 and another link between 4 & 5 the two coil pairs will be in series/parallel, ie 208v + 32v parallel with 208v + 32v = 240v. The 448v option is available to you if you link either 3 & 5 or 2 & 6, giving three coils in series, 208v + 32v + 208v = 448v.

Regards,

Chas.

[gpigeon]

Chas,
Yes you are correct. 35 years of home brew must be dulling my grey matter!!!!
Thanks for your input. It all makes more sense now.

I still have not moved the m/c back to the old shed but I do think that the problem stems from the long conductors (80m of 16mm2) and not having a "D" curve MCB.

For the moment I will be content with operating my Transtig 180 as a stick m/c although, it does not seem to have the output of the stick m/c.
Rgds. Bill.