What is "good" arc voltage?

Well, made my first cuts with the Pro yesterday and I am more than pleased. I was cutting 16 gauge hot rolled with the Razorweld 45 at 30 amps. My nominal voltage was right in the 113.4 range. THC appeared to work exactly as designed. Question…. What would be “normal” arc voltage? Should I expect it to change with varying thicknesses / types of metal and / or amperage? Also…. If it can be explained simply, what exactly is the “arc voltage” and how does it differ from the amp setting of the plasma cutter.

Awesome to hear. I 've had my Pro since November and have been enjoying it very much.

Nominal Arc voltage listed on your cut charts as Voltage in volts is determined at the manufacture’s testing stage. The manufacturer sets up repeatable test scenarios to provided the best quality of or best production cut . From these tests they prove their engineered math and populate the cut charts for our use. So we do not have to guess at the voltage’s value or use a system like SMART voltage to set it for us.

On this cut chart page 113 out of the service manual
shows the voltage target as 125 volts @ 45amps
very close to what your SMART voltage registered at 113.4 volts @ 30amps

Yes, Changes to Resistant or Amperage will effect the Voltage.

Your machine wants to maintain the Amperage that it is set for.

The Voltage is only measured by us and used to tell the THC how to act.

Arc Voltage is the difference in potential between two points in a circuit that contains an Arc. Pressure.

Attached is a Clip from Page 345 of the service manual

the points for raw arc voltage J22 and J9. This is one place where this potential difference could be measured

Also shows J17 to the voltage divider then out the CPC.
port this is where the Langmuir measures its voltage from.

They are two separate measurements.

Voltage. Potential Difference or Pressure of the Circuit

Amperage. Volume of Electrons

As a side note under the the THC Settings it notes the " *SMART Voltage only for 14ga and thicker"
Attached screen shots from Fire Control .


I’ve been trying to run close to book cut chart and I’ve been entering my nominal voltage when set to 45amps.

Also a note reaffirming that voltage is condition dependent from the 45xp service manual.


Langmuir system THC manual

Powermax45 XP Service Manual (809230 revision 2)

To answer the title Question " What is “good” arc voltage?"

The one that produces a repeatable cut in quality for all the repeatable variables.



well done!!..
that is a reply worthy of respect… !!!


Thanks for a great explanation! Your reply was well worth the read:+1:

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Hey Brian check out these 2 videos from D & N Custom Creations they are very good.


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Thank you very much for your detailed response. As with anything, I think the more I get to understand how this works, it will make troubleshooting that much easier if (when) the time comes. Thank you again!

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Thank you very much for forwarding these videos. This guy did a great job explaining how the system works. Thank you again!

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