110v or 220v plasma cutter choice

Hello again. I work on lots of plasma cutters and I never seen one that will run on less than 100 output volts. At 50 amps that comes to to 5ooo watts. A 120 volt input at 30 amps makes only 3600 watts and we have not yet allowed for any resistance losses. Now I'm curious, what make and model is your machine?
 
I recently bought a Hobart 250CI plasma cutter. It is 110V only and completely self-contained. It is rated to cut 1/4" crs, but, it is a struggle. I am wondering if there are any tricks to cutting at the limits of the machine. I move the cutter head very slowly watching the sparks to get them through the metal and not coming back at me. I use the wheel accessory to maintain the distance above the metal, approximately 1/8 inch. I have even run 2 and 3 passes through the cut slot to see if that works. It does somewhat. Anything else I should try? Also, I keep the ground clamp as close to the work as reasonable.
Thanks
NodakGary
 
NodakGary said:
I recently bought a Hobart 250CI plasma cutter. It is 110V only and completely self-contained. It is rated to cut 1/4" crs, but, it is a struggle. I am wondering if there are any tricks to cutting at the limits of the machine. I move the cutter head very slowly watching the sparks to get them through the metal and not coming back at me. I use the wheel accessory to maintain the distance above the metal, approximately 1/8 inch. I have even run 2 and 3 passes through the cut slot to see if that works. It does somewhat. Anything else I should try? Also, I keep the ground clamp as close to the work as reasonable.
Thanks
NodakGary
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Hi NodakGary,

unfortunately the 110v plasma units need to be run on a 20 amp circuit or you will not get full potential from the machine. A clean,constant, regulated air supply is also essential. some smaller air compressors have a hard time maintaining nominal 60 psi at flow rates compatible with the plasma unit.

they are great for sheet metal and an occasional cuts in thicker gauged materials.
it may cut 1/4" stuff,
but, it's going to look like a beaver chewed it off and you'll need to do a lot of cleanup work afterwards.

none the less they are most useful on lighter gauge stuff.
 



Hi Micke

I don’t mean tobe argumentative but here is a sample of the plasma cutter advertisements. The mathematicsdoesn’t work.

AirInverter Plasma Cutter Welder. 110V OR 220V

Plasma Cutter Specs:
208/220vac 50/60HZ InputSingle Phase 1PH
110/120vac 50/60HZ InputSingle Phase 1PH
50amp cut draws 25Amps
230V No Load Voltage, 100-115V Working Voltage

So the outputvoltage is practically the same as the input voltage. That would require 50-60amps of input at 120 AC. Notice that they cleverly don’t tell you the voltagein this statement “50amp cutdraws 25Amps”


 
Hi, no problems and there are good reasons to put a big question mark after cheap cutters specs. as you do. The math is not in favor to the 110 V mode and the advertised figures are not terribly realistic.

The output voltage from Plasma cutters in this class is normally only around 95 V and the length of the arc will also came into place to determine the actual voltage. It would take 40+ amps on the 110V side to deliver 50 amps continuously. I don't think the amp rating on plasma cutters is continuous current delivery. The voltage on the torch is not pure DC so the average current will be lower, hence explaining the possibility to run so called 50 amps on 110 V on a 30 amp fuse. The average continuous current is most certainly lower than 50 amps at the 50 A setting. The output waveform and current is however probably the same though on cheap machines independent of 220 or 110 V power.

I personally have a 3-phase 400 V cutter since this mains power is available here and I'm sure a 110 V single phase cutter is a lot weaker even it is has the same output current rating.

But based on the thoughts above I am quite sure TS question about if he could use the 110 V tap for the plasma is - yes. What I would do in the same situation since he has both 110 and 220 V available would be to switch between them and see if it makes any significant difference for him.
 
Thank you all for the comments. I really appreciate the input. Please let me digress a little bit.

I am a retired mining engineer with degrees from Colorado School of Mines and others. I am basically a dirt dauber with a desire now to take big pieces of metal and make them smaller.

My question was really one of basic understanding. It is now clear to me that the specs may not present a total picture of the abilities of the plasma cutter. During my research I looked at several plasma cutters and weighed the reviews.

Not wanting to spend ~ $1500 for the "BLUE" standard I opted to spend, say, $400 for a LOTOS LTP5000D from the USA distributor which will arrive on Monday. I believe, if it works, it will be satisfactory for me. Just as the Harbor Freight 135 amp dc welder is doing as I teach myself to weld.

So back to my original question, if the electronics truly do what the specs say it will do why would I want to change the plug to run it on 240 volts? I understand the wattage math.

I will make an adapter cable to test for differences in performance, if any.
 
Hi
If you try it on the same material, same torch parts, and air pressure ( suggest 3/8 mild steel plate ) I think you will find that it cuts much faster when wired for 230 volts. Out of curiosity let us know how you make out. Hope that answers your question.
 
Good suggestion.

I thought I would start with 3/8" and then test it on 1/2" steel of the same type keeping all the variables the same. Using an adapter the switch should be achieved quickly.

I suspect, as I think you do also, there will be better cuts at 240 volts at least on the thicker material.

I am not sure how valid my observations will be because I have no experience with these tools, unless it becomes an obvious cut or no cut scenario.

Your comment about cutting faster at 240v is very helpful and does answer my question.

Does that then also translate into cutting thicker material but at a slower rate?

I believe this unit has a severance rating at 3/4". I really don't know how severance differs from any other cut other than by the rate of speed at which one makes the cut.
 
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Hi
I suspect that it won't cut 1/2" material at all on 120 Volt AC, and it will cut 3/8" much faster and cleaner. Good Luck.
 
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