old stick welding m/c

[gpigeon]

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.

[Grandad-5]

I know nothing about 2 phase power so cannot help specifically, but it seems to me that there are 3 variables here. The old power point, the new one and the machine itself.

The unit was working on the old PP but not on the new. Is it possible to take the machine back to your old shed and try it there?
If so, and it works, the problem is in your new shed PP.

When something works ok in one environment but not another, it seems logical to look at the new environment first.

I can only see 3 possibilities.
1. Something happened to the machine in transit.
2. New PP is wired incorrectly.
3. Old PP was wired incorrectly but matched the machine that was wired to suit. (Either intentionally or by quirk of luck)

Jim

[gpigeon]

I can only see 3 possibilities.
1. Something happened to the machine in transit.
2. New PP is wired incorrectly.
3. Old PP was wired incorrectly but matched the machine that was wired to suit. (Either intentionally or by quirk of luck)

Jim

Jim (Grandad 5)......very logical thinking! How come I'm older than you but didn't think so logically?
I looked at the more difficult solutions first! However, I had checked the outlets and they are both wired up correctly.
I will move the m/c back to the old shed tomorrow in order to eliminate the damage in transit, but methinks that option is unlikely so really I'm back to square 1.

Thanks.
Bill.

[Grandad-5]

You're very complimentary Bill, which I appreciate even if its not 100% warranted.

I will move the m/c back to the old shed tomorrow in order to eliminate the damage in transit, but methinks that option is unlikely so really I'm back to square 1.

One of my favourite authors is Sir Arthur Conan Doyle.
Through his character of Sherlock Holmes he states.

"When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth"

You seem to have eliminated two of the three options.

Cheers
Jim

[inverter_weld]

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.

H i,

Have you checked for differences in the circuit protection between both sites? You may have a HRC fuse block at the old site but an MCB (mini circuit breaker) at the new one. As a result there may be differences in KA rating of the protection and this will manifest as sensitivity to tripping on high inrush currents when turning on. You can overcome this by using breakers designed for high inrush such as motor start types.

Basic KA Rating Explanation: KA rating of protective devices increases up the supply line so that a short circuit at the end of the line trips the first upstream breaker. If you had the same KA rating for all protective devices on a supply line, a short circuit in the kitchen on the 20th floor of a building would take out the main breaker in the basement. KA rating is not the same as trip current. For example a 20 amp breaker with a 4KA rating will trip before a 20 amp breaker with a 10KA rating. The KA rating is the absolute max current that will flow for the microsecond during fault conditions.


Regards
Pete (Tokentools Welding Machines)

[Chas]

Your line to line voltage should be 400-415, not the 457 volts you say you have measured. Are you sure this is the actual voltage and not a typo? If so, it might explain your tripping circuit breaker.

Chas.

[danielhobby]

i cant give you specific info but your machine can possably be wired to run off of 240volt single phase,also 2 phase supply or three phase supply depending on the placement of those links you mention,i also have a couple of similar machines.try checking how many phases are present/live in your old outlet.please speak to an electrician.regards danny

[gpigeon]

Your line to line voltage should be 400-415, not the 457 volts you say you have measured. Are you sure this is the actual voltage and not a typo? If so, it might explain your tripping circuit breaker.

Chas.

Chas,
Rechecked the line voltage. Ph to ph is definitely around 450-455V and phase to N is 258. 2x grid feed inverters on same system also show line voltage of 258VAC. Does seem high! But still, that does not explain why the welder worked fine in the old shed on that voltage and will not work now in the new shed 80m away on a sub circuit.

Haven't had a chance yet to move the m/c back to the old shed for a re check.

No HRC fuses fitted! All CB's.

[inverter_weld]

Chas,
Rechecked the line voltage. Ph to ph is definitely around 450-455V and phase to N is 258. 2x grid feed inverters on same system also show line voltage of 258VAC. Does seem high! But still, that does not explain why the welder worked fine in the old shed on that voltage and will not work now in the new shed 80m away on a sub circuit.

Haven't had a chance yet to move the m/c back to the old shed for a re check.

No HRC fuses fitted! All CB's.

Did you check the KA rating of the breakers? There should be a number followed by KA.

Cheers
Pete

[Dan]

Basic KA Rating Explanation: KA rating of protective devices increases up the supply line so that a short circuit at the end of the line trips the first upstream breaker. If you had the same KA rating for all protective devices on a supply line, a short circuit in the kitchen on the 20th floor of a building would take out the main breaker in the basement. KA rating is not the same as trip current. For example a 20 amp breaker with a 4KA rating will trip before a 20 amp breaker with a 10KA rating. The KA rating is the absolute max current that will flow for the microsecond during fault conditions.


Regards
Pete (Tokentools Welding Machines)

I don't think this is correct.

ka rating refers to maximum fault that the cb can safely interrupt without damage.

[inverter_weld]

I don't think this is correct.

ka rating refers to maximum fault that the cb can safely interrupt without damage.

Hi Dan,

The technical explanation can be found here.

http://download.hager.com/Hager.ie/f..._Technical.pdf

Goto page 129 of the pdf.

You may have missed my post about the relevance of the KA rating from yesterday.
Cheers
Pete

[Dan]

G'day Pete,

If you go to page 132 of that PDF you linked you will see the explanation of discrimination. I think this is what you are referring to with your 20 floor building explanation. Ka ratings are not used for discrimination.

[RustyArc]

kA ratings for breakers are all about fault currents, not inrush currents. For a device that has an particularly high and/or long intial current draw, a sparky may choose to use a breaker with a different trip *curve* - ie. most are C curve, but he may choose a D curve for example.

[inverter_weld]

Thanks Rusty and Dan,

You are both right.

Cheers
Pete

[Jekyll and Hyde]

Jim (Grandad 5)......very logical thinking! How come I'm older than you but didn't think so logically?
I looked at the more difficult solutions first! However, I had checked the outlets and they are both wired up correctly.
I will move the m/c back to the old shed tomorrow in order to eliminate the damage in transit, but methinks that option is unlikely so really I'm back to square 1.

Thanks.
Bill.

What about the other end of the cabling - by which I mean the switchboard end? Perhaps the phases got flipped on at the switchboard end of the run to the new shed (or the old one is incorrect). My first thought, like Grandad (that's kind of weird to say...) is that someone somewhere has mucked up a connection. While you're at that though, definitely have a look at your breakers as has been said by a few others.

I have a 250amp transformer tig that, like your machine, can run on 2 of 3 phases as well as 240v. I have mine running off 240v, through a 40 amp (was supposed to be 50, but anyway, I'll sort that one day) circuit breaker, and quite often just turning the machine on instantly trips the breaker. If I turn the switch on very slowly, it seems to happen less. Yet, once it's on I can weld up to about 175amps on AC without tripping the breaker, and more on DC. I can only assume that its due to current required to 'saturate' (would that be the right term?) the transformer/s so that they are ready to go when you start the arc.

I'm interested by comments here about a 'D' curve breaker though, mine (aside from being a 40amp instead of the 50 it was supposed to be, something I only realised recently after 2 years) appears to be a 'C' curve. Do the gurus think changing to a 'D' might help this mildly annoying situation (as I want to get a 50 amp put in anyway)?

Assuming a reasonably careful move, the only thing I could really see happening to the machine on the move is a break in one wire in the lead (maybe at the plug) that's allowed a short to occur.... I suppose all will be revealed when you move it back...