Voltage Sensing Wire Feeder

Date 05-31-2003 23:31

In theory, that is exactly what they do. In actual practice, you will find that the range of adjustment on the wire speed is so narrow where a good bead can be made that keeping things exactly in adjustment can be somewhat of a problem.
In my experience, the larger of a machine you use, the less the voltage will vary.I have had OK results using a Lincoln LN-25
with a 600 amp CC machine.
Short arc performance will not be as good as can be had with a CV power source.
Also, no weldments that need to be inspected and certified to code will be made with a non- code power source.

By Niekie3 (***)

Date 06-02-2003 19:35

Hi Supermechanic

Just a small clarification. It is not possible to weld short circuit with a CC power source using a voltage sensing wire feeder.

Regards
Niekie Jooste
Fabristruct Solutions

By supermechanic (**)

Date 06-03-2003 04:49

Niekie, you should see what can be done with a 15 farad capacitor bank on my 600 amp CC. welder. (How many joules does that work out to at 21 arc volts?) I have enough instantanious current to vaporise a Hobart 600 amp gun.(No, I didnt do that on purpose).
That big of a cap bank has a strangely curious way of straightening out the droop on a smaw rig.

Back to the subject, I really don't know why certain manufacturers claim that a feeder will work on CC, as the applications for it are rather narrow. I was merely expressing the fact that a voltage sensing feeder is a compromise, and not a very good one at that, as I learned the hard way.

PS. I've quailfied my power source and process for my application (architectural free-form arch structures).

On a far horizion I see some new equipment, for now, money dictates that I keep the present set-up.
supermechanic

By Niekie3 (***)

Date 06-03-2003 17:13

Hi Supermechanic

I must agree - A voltage sensing wire feeder is very much a plan "B". A poor plan B at that!

Regards
Niekie Jooste

By Fred Alvarez Date 06-03-2003 21:03

Thanks for the replies. It makes sense that voltage sensing wire feeders would work better with larger diameter wires and bigger power sources. Slight variations in the voltage at higher volts would have less effect, percentagewise, than at lower voltage. Just as a guess, I imagine self shielded flux core wires that use DC+, which typically require higher voltage, would run better in the voltage sensing units.

Hey Supermechanic, I like the "in theory" part. You know the difference between theory and reality? "In theory, there is no difference. In reality, there always is."

By supermechanic (**)

Date 06-04-2003 12:40

Fred , flux core runs OK. One time it was explained to me that the arc with flux core is more like a spray-type transfer than anything else, as that, it works with a voltage sensing feeder.

By Michael Sherman (***)

Date 06-04-2003 12:52

My LN-25 voltage sensing wire feeders work very well on CV machines. We were never able to achieve anything other than spray transfer when used with a constant current machine. We only tried once or twice but that was enough for us to update our gas drives so they all have CV.

Mike Sherman
Shermans Welding

By ScottV

Date 06-04-2003 13:05

I have tried using a Miller s32s feeder,and a Esab mobliemaster IV auto voltage sensing feeder using a cc/dc inverter.It will not work at all,only Spray tranfer with that setup.I do know one thing,it's not worth wasting your time.

By 357max

Date 06-10-2003 22:14

You are correct the voltage is monitored and the wfs is fluctuating to the voltage. Remember on a constant current machine you are setting current and it stays "constant". When you weld with the GMAW-S (short circuit metal transfer) process with 0.035" wire it takes about 350 amperes (current) to clear the short circuit. Well if you set 125 amps on the machine it will only give you that. The wire gets hot and noodles on the plate. There is not enough amperage to clear the short circuit.
If the machine has constant voltage. The machine will produce enough amperage to clear the short circuit plus more and the voltage remains constant. You would set 17.5 to 20 volts on the machine which would determine the arc length and transfer mode. A voltage sensing feeder is great if you want to eliminate a control cord back to the machine.
Constant voltage is easy to understand. It is what our house wiring is all about. The voltage stays constant and the current (amperage) changes with the load. Granted the fuses or circuit breaker is a limiting device. Hope this helps.