AC to DC
AC to DC
(OP)
I have to change single phase AC 220V welding machine into DC welding Machine. I have used full wave diode bridge rectifier but the output voltage and Current are not smooth. Is it possible to add inductor in series and capacitor in parallel to get better results, and how to calculate the parameters.





RE: AC to DC
RE: AC to DC
RE: AC to DC
An inductor in series is essential to smooth out the welding current but with a single phase rectified power source you have little to no chance of getting a continuous output current from your welding set.
Big welding sets were once built using a motor generator set that gave good smoothish DC for the welding supply, it is immaterial what the prime source of power (single phase motor, 3 phase or IC engine) is in these sets since the output current comes from the torque applied to the generator shaft.
A three phase supply can be rectified and produce an EMF that only falls to 86% of the peak AC voltage at 6 times the input frequency (50/60Hz in ,300/360Hz out)this in association with an inductor (choke) will provide a suitable source of welding current for DC welding.
If the same rectifier/filter is used with a single phase input the source EMF will fall to zero twice per input cycle and result in a discontiuous weld current.
By installing an inductor you will improve the smoothness but will not eliminate the high ripple current, an increse in rectifier input voltage will be required to accomodate the voltage drop over the inductor.
If you can use a 3 phase input for the power source if you require a very smooth welding current. Its a wee bit more complex but it will work.
RE: AC to DC
The DC welding machine's AC characteristics are critical in how well the welding machine welds.
When Glenn Pacific was building welders, the procedure was to design the welder and then make changes to improve the welding characteristics. A change would be made and if it improved the characteristics good, if welding characteristics were worse, the an opposite change would be made and tested. And so on.
RE: AC to DC
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: AC to DC
RE: AC to DC
RE: AC to DC
What brand and model,(mostly),are they? Maybe we can figure out a solution...
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com