Graveltech
New Member
I noticed there are some welder experts on here. Awesome site!
I purchased a used Lincoln CV 250 Mig Welder (same as CV 300) at auction. I made a big mistake and read the voltage selection guide, but didn't realize that it was 3 phase only. So, I built a 10 hp phase converter. Seemed to work, but as I learned to Mig weld, something never seemed right. I realized that the voltage was all over the map, but usually high. I could turn down the heat setting, and it seemed to work but then when the welder was shut off and back on again, the display would display a low reading (as set) but the output was much higher.
I realized that there was a right way and wrong way to hook up the three phases. One connection worked better then another, depending on where the manufactured phase was.
Anyway, I figured it was just a bad connection internal to the welder. But found none, and after cleaning all internal connections and checking for obvious problems on the PCBs, no improvement.
So, I started taking measurements and thought I was on to something. The tip voltage was much less then the displayed voltage. And yes, with the phase connected improperly, it was MUCH worse. I see that two phases at about 13 Volts are fed into the Voltage Control Board. So it is important, that the fake phase not be one of these. And by the way, for what it's worth, this is a Constant Voltage Welder.
Before I did anything else, I loaded the welder onto my truck and took it to a friends with a large 600 volt 3 phase generator, possibly to take my phase converter out of the equation. But alas, same thing. Now, I should add, I NEVER did take readings while welding, only no load readings.
There is a big cap and resistor on the output, by the way.
Well, I thought I was onto something. But before I left, I thought out of curiosity, I would measure one of their welders. It was another single phase lincoln, around 250 amps, but not constant voltage. To my surprise, it behaved exactly like mine, when comparing no load panel voltage to measured tip voltage! Oh, and I used a Fluke True RMS digital meter.
Now, I am totally confused and would like some input.
One other thing. The MOVs on the 600 volt line were blown up when I got the machine. They are totally absent, and I am curious what values to use. They must be different, depending on the chosen operating voltage, I would guess.
Thanks
I purchased a used Lincoln CV 250 Mig Welder (same as CV 300) at auction. I made a big mistake and read the voltage selection guide, but didn't realize that it was 3 phase only. So, I built a 10 hp phase converter. Seemed to work, but as I learned to Mig weld, something never seemed right. I realized that the voltage was all over the map, but usually high. I could turn down the heat setting, and it seemed to work but then when the welder was shut off and back on again, the display would display a low reading (as set) but the output was much higher.
I realized that there was a right way and wrong way to hook up the three phases. One connection worked better then another, depending on where the manufactured phase was.
Anyway, I figured it was just a bad connection internal to the welder. But found none, and after cleaning all internal connections and checking for obvious problems on the PCBs, no improvement.
So, I started taking measurements and thought I was on to something. The tip voltage was much less then the displayed voltage. And yes, with the phase connected improperly, it was MUCH worse. I see that two phases at about 13 Volts are fed into the Voltage Control Board. So it is important, that the fake phase not be one of these. And by the way, for what it's worth, this is a Constant Voltage Welder.
Before I did anything else, I loaded the welder onto my truck and took it to a friends with a large 600 volt 3 phase generator, possibly to take my phase converter out of the equation. But alas, same thing. Now, I should add, I NEVER did take readings while welding, only no load readings.
There is a big cap and resistor on the output, by the way.
Well, I thought I was onto something. But before I left, I thought out of curiosity, I would measure one of their welders. It was another single phase lincoln, around 250 amps, but not constant voltage. To my surprise, it behaved exactly like mine, when comparing no load panel voltage to measured tip voltage! Oh, and I used a Fluke True RMS digital meter.
Now, I am totally confused and would like some input.
One other thing. The MOVs on the 600 volt line were blown up when I got the machine. They are totally absent, and I am curious what values to use. They must be different, depending on the chosen operating voltage, I would guess.
Thanks