Lincoln AC 225 AMP, What does it take to burn it up?

[npalen]

I picked up this item on ebay and getting around to seeing how it works today. My concern is what amperage I can safely run without burning up my Lincoln AC225 "tombstone". I tried it on 90 Amps for a a minute or so and it does produce a lot of heat with 1/4" electrodes on a piece of 3" Ibeam. I know there is a max duty cycle for a given amperage but not sure if the Lincoln has a thermo switch of some kind to protect it or what. I don't have a large oxyfuel torch so needing this twin arc for miscellaneous straightening etc.
Also wondering what is maximum diameter electrodes I should be using for maximum heat output. All help is appreciated.


Edit: Disregard the stinger shown in the picture. Apparently the seller thought it was part of the "package". It's an antique for sure.

 

[k0ua]

I picked up this item on ebay and getting around to seeing how it works today. My concern is what amperage I can safely run without burning up my Lincoln AC225 "tombstone". I tried it on 90 Amps for a a minute or so and it does produce a lot of heat with 1/4" electrodes on a piece of 3" Ibeam. I know there is a max duty cycle for a given amperage but not sure if the Lincoln has a thermo switch of some kind to protect it or what. I don't have a large oxyfuel torch so needing this twin arc for miscellaneous straightening etc.
Also wondering what is maximum diameter electrodes I should be using for maximum heat output. All help is appreciated.
View attachment 337918

Editing again... I misunderstood what you said

the AC225 will run 75 amps continuous. so your 90 amps is not hurting it any. Although I don't see how you would weld much with 1/4 inch electrodes at 90 amps. That is 1/8 inch electrode territory for most electrodes at best, and some 3/32 need to be run in that region. 1/4 inch electrodes. depending on what they are would run at much higher amperages. I don't think the AC225 needs to be thinking about any 1/4 inch electrodes, Did you try the millerwelds website, they have a nice calculator for recommended amperages and electrode size.

James K0UA

 

[k0ua]

Here is what the lincoln manual says about duty cycle looks like 20% I was always told that they would run continous at 75.. but I guess not.


Duty Cycle
(For Codes 11604 and below). The 60 Hz welders are rated
20% duty cycle and the 50 Hz welders are rated 15% duty
cycle for the welding current shown on each switch position.
(For Codes 11674 and above). The 60 Hz welders are rated
20% duty cycle and the 50 Hz welders are rated 13% duty
cycle for the welding current shown on each switch position.
Duty cycle is based on a ten minute period. This means that
the arc can be drawn for 2 minutes out of each ten minute
period (with a 20% duty cycle unit) without any danger of
overheating. If the welder is used for more than 2 minutes
during several successive ten minute periods, it may overheat. Be sure to leave the unit “on” during each 10 minute
period to let the fan motor run for adequate cooling.

3/16 is the largest electrode show, at 200 to 225 depending on which electrode is chosen. Most welding is going to be done with 1/8 or smaller electrodes with that machine.
Overheating reduces welder life.

 

[npalen]

Guys, I'm trying to heat metal rather than weld but I do understand that amps output capability would be the same for either. I appreciate the info on duty cycle for the 225AC Lincoln. I'm testing the twin carbon arc torch shown below. I thought I had read somewhere that 5/16" is the maximum carbon arc electrode (not welding electrode) recommended for 225 VAC. I wonder if there is any advantage of 5/16" over 1/4" other than longer consumable life?
My main question is what happens if you exceed duty cycle? Catastrophic failure or shortened life? I take it that there is no thermal overload protection on the Lincoln?
Here's a better picture of the twin carbon arc torch:

 

[k0ua]

What I can read in the manual on their website, the AC225 does not have a secondary thermal overload shutdown. The AC/DC one does, but not the AC.. my guess is when you exceed the duty cycle, it lets out the "magic smoke". I am guessing possible transformer winding damage could occur. I don't know a lot about the carbon arc torch. But I always wanted to try one. I have heard you better cover everybit of your skin, as it makes a LOT of UV light, way more than normal welding. Also it needs to be done outside as there are some interesting fumes and gases given off. Let us know how it works out please.

James K0UA

 

[npalen]

Demonstration of The Carbon Arc Torch - YouTube
James, I appreciate your input. This is a good video for anyone unfamiliar with a twin carbon arc torch. I have some repair to do on my box scraper consisting of straightening some 5/16" steel and needed the torch for heating the metal. I'll try to post some pix in a few days.

 

[Arc weld]

The older models had a circle around the 75 amp setting indicating it had a higher duty cycle specifically for things like a carbon arc torch or for thawing water pipes. Lincoln used to make a special attachment for thawing water pipes but it has been discontinued. Probably because of the fire risk. It was never sold in Canada because it didn't meet CSA approval. Lincoln older manuals on their website explaining the 75 amp setting.

 

[npalen]

My Lincoln 225AC has the circle on the 75 amp setting. Would have never known what it was for.

 

[DXN1EL]

npalen how did it go? is the carbon arc torch bad for welders like it is gouging?

 

[Soundguy]

i'm surprised at the low duty cycle. must be individual taps.. as opposed to the continous xformer tpe like hobart has. 90a is still in 100% duty cycle on a hobart 235XL AC