leads which way round?

[magnet]

Hello. I have just bought a second hand arc set, unlike others that I own it has no + or - marked on the terminals where the welding supply leads go.My question is, can they go either way round, and if they cant how can I find out which is which. Thanks in advance Magnet

 

[scarecrow]

is it ac or dc I have seen a couple of inverter with no positive or negative markings if it is ac it will only work one-way quickest way is to try it

 

[magnet]

is it ac or dc I have seen a couple of inverter with no positive or negative markings if it is ac it will only work one-way quickest way is to try it

Cheers Scarecrow I already tried it and it works both ways round, my concern was weather I would be doing any harm to it with the leads in the wrong place? cheers Magnet

 

[SwissTony]

Is there a make/model number on the welder?

 

[decepticon]

i was under the impression that with AC it does'nt matter which way round the leads were and that would explain why there is no +/-
doubt you could do any damage if wrong way round though
cheers

 

[trevatxtal]

Welder polarity.

Hello Magnet
1 With a true AC welder the polarity does not matter as heat dissipation is 50-50 due to the current alternating both ways.
2 However if your machine is pulse controlled modern type then polarity may be important. (converter welders)
3 A DC welder is different approx 60 percent of the Energy is dissipated on the + and 40 percent on the - .
So for deep penetration the + is connected to the work and weld rod to the -.
For thin sheet work reverse the connections and then there is less chance of blow through.

Source of this information is " Electric Arc Welding published by Newnes Technical Books ISBN No 0 408 00132 1"
Hope this helps
Trev

 

[oilcooled :)]

travatxtal you deffo have that the wrong way around. dc flows from (x amount lets say 100v) from + to 0V at -, so when you set up your weld dcep (direct current electrode possitive) you can put more heat into the rod and therfore around the area where your welding has more heat hence better penetration. if you do it vicia versa DCEN (direct current electrode negative) more heat can be dissapated across the piece, and this enables less heat at the end of the rod and less penetration. this was gone through 1000 on this forum, and its still getting mixed up, there it is written in stone, although someone will try and prove me wrong, it aint rocket science, its common sence. sorry for the rant.

 

[magnet]

no longer confused

Thanks one and all for your help. Its funny i am quite a competent welder and have been at it for over 20 years but I now realise i know nothing about the plant itself! Once again thanks for your input . Atb Magnet

 

[trevatxtal]

Polarity on MMA welding.

travatxtal you deffo have that the wrong way around. dc flows from (x amount lets say 100v) from + to 0V at -, so when you set up your weld dcep (direct current electrode possitive) you can put more heat into the rod and therfore around the area where your welding has more heat hence better penetration. if you do it vicia versa DCEN (direct current electrode negative) more heat can be dissapated across the piece, and this enables less heat at the end of the rod and less penetration. this was gone through 1000 on this forum, and its still getting mixed up, there it is written in stone, although someone will try and prove me wrong, it aint rocket science, its common sence. sorry for the rant.

Sorry Oilcooled
For the polarity heating I have only quoted the most respected experts in the field of welding.
Kenneth Leake, and Norman J. Henthorne
I do not believe they have been proved wrong.
You may make your own tests as to which is the hottest + or - by timing two identical weld rods. The one that burns the fastest is the hottest.
This test/experiment is done by most students in welding institutes and training schools.
The "So for deep penetration the + is connected to the work and weld rod to the -.
For thin sheet work reverse the connections and then there is less chance of blow through." is mine from personal and colleagues experience, it to can be tested by experiment.

 

[Sid]

For the polarity heating I have only quoted the most respected experts in the field of welding.
Kenneth Leake, and Norman J. Henthorne
I do not believe they have been proved wrong.

The exact ratio of heating on either side of the arc varies depending on your source, but the +ve side receives the greater amount. This is why Tig welding is normally carried out DCEN, and the balance you use on an AC machine would consider this disparity in heating either side of the arc.

You may make your own tests as to which is the hottest + or - by timing two identical weld rods. The one that burns the fastest is the hottest.
This test/experiment is done by most students in welding institutes and training schools.
The "So for deep penetration the + is connected to the work and weld rod to the -.
For thin sheet work reverse the connections and then there is less chance of blow through." is mine from personal and colleagues experience, it to can be tested by experiment.

The burn off rate does confuse on a 'heat on either side of the arc' basis, but it is probably not the only thing affecting burn off rate. DCEN consumes the rod faster, but it also has the shallower weld penetration. DCEP makes the rod side hotter, and it has a deeper penetration. This is universally agreed. See this link http://en.wikipedia.org/wiki/Shielded_metal_arc_welding#Power_supply

Also what you must remember, unlike Tig, where no material flows across the arc, with MMA the rod is melted and is fired across. This has the consequence that all the heat ends up on the weldment side. With DCEP, the spray of metal is hotter, and so the weld penetration is deeper. With DCEN, the sprayed metal is cooler, and so creates wider shallower welds.

 

[oilcooled :)]

thanks sid knew i wasnt talking threw my ****