Volts vs. Amps when welding

   / Volts vs. Amps when welding #1  
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joshuabardwell

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I just watched this video.


I was surprised to hear him say that, in general, a low OCV is more desirable. I have heard that a higher OCV is needed to run 6010 properly. Maybe this is a case of "Goldilocks"--not too little, not too much, but just right? The other thing that surprised me was that a higher OCV is conducive to sticking the electrode and snuffing the arc when short-arcing, whereas a low OCV is more conducive to "digging" and keeping the arc going. This just seems backwards, since I would think high voltage = more energy.

Thinking about the second point: I = P / V. If 40 in gear 2 and 70 in gear 1 produce the same current output, then:

I = P2 / 40 = P1 / 70
P2 / 40 = P1 / 70
P2 / P1 = 70 / 40
P2 / P1 = 1.75

This 1.75 number is not actually correct, since 70 and 40 are not actually voltage values, but are an arbitrary representation of voltage on a 1-100 scale. Nevertheless... 40-in-gear-2 produces more power (heat / watts) at the same current (amperage) than 70-in-gear-1. This helps explain why the arc is harder to snuff, but then why does the lower-voltage setting produce a faster-solidifying puddle? It seems like putting more heat into the puddle would cause the puddle to be more liquid, not less.

Can anybody help me make sense of this?
 
   / Volts vs. Amps when welding #2  
As the arc length changes, the voltage accross the arc changes.
Longer arc = higher voltage.
Shorter arc = lower voltage.

So at a lower overall voltage from the machine, the change in voltage from the change in arc length will be of a greater proportion. This is part of what some call 'dig', or 'arc force', or 'soft/crisp' arc, etc.

As far as how this effects how the puddle solidifys, I'm not sure.
 
   / Volts vs. Amps when welding #3  
Shield Arc posted a good explanation from an SA 200 manual. As far as open circuit volts for shop machines, it depends a lot on the individual machine. A lot of inverters only put out about 60 OCV yet strike and hold an arc 100 times easier than an AC buzz box. If a buzz box only put out 60 OCV it would be very hard to strike and maintain an arc. The 7018AC rods are listing as being for low OCV machines yet buzz boxes often have the same or higher OCV volts than other machines. Volts don't give heat, amps give heat. Maybe it's like HP and torque, High OCV is like high HP low torque and low OCV is like high torque low HP and the high torque is what keeps rods from sticking? Lincoln figured this out eons ago but it can be complicated to understand. I don't have my book from school anymore but it had a whole chapter on Lincoln Dual Continuous Control machines such as SAE 300's and 400's. The Lincoln manual goes into some detail on the affects of varying the OCV volts while keeping the amps about the same.
 
   / Volts vs. Amps when welding #4  
Actually neither volts or amps give heat by themselves. Wattage is translated as heat and that is VxA.
 
   / Volts vs. Amps when welding #5  
For welding, heat is generally referred to as amps because the voltage isn't nearly as adjustable. A machine like an SA 200 will have about 55-95 OCV but 40-300+ amps. A shop machine won't adjust the voltage anywhere as much unless it's an old generator. Voltage is the flow and amps is the push. It's kind of like the debate over how you get electrocuted. Some people say high volts kill you and some people say high amps kill you. It is the right combination of both that will kill you.
 
   / Volts vs. Amps when welding #7  
Can people get killed by a welding machine?
 
   / Volts vs. Amps when welding
  • Thread Starter
#8  
DXN1EL said:
Can people get killed by a welding machine?
Click to expand...

Yes, but not exactly how you might think. Generally, the OCV is low enough that you might feel a tingle, but you probably won't get electrocuted. The way people get killed is if, for example, you are laying on the ground, and the ground is wet, and your stinger lead is frayed, so you get shocked. It's important to remember that you need to insulate yourself from the stinger, but also the ground, to avoid any stray currents accidentally going through your body.
 
   / Volts vs. Amps when welding #9  
joshuabardwell said:
Yes, but not exactly how you might think. Generally, the OCV is low enough that you might feel a tingle, but you probably won't get electrocuted. The way people get killed is if, for example, you are laying on the ground, and the ground is wet, and your stinger lead is frayed, so you get shocked. It's important to remember that you need to insulate yourself from the stinger, but also the ground, to avoid any stray currents accidentally going through your body.
Click to expand...

Or use one of our new digital units with VRD.
 
   / Volts vs. Amps when welding #10  
I read somewhere the reason for using amps was to prevent that?

The other day I was welding scrap, I had one hand on the table but I am not sure if I was touching the stinger (I accidentally broke the back side the metal is exposed) any way I felt a little current.
Was that the welder or do I just felt something and the welder has nothing to do with it?:confused:

Like I said i read somewhere that that why amp are used so people don't get electrocuted?? :confused3:
 
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