Mig upgrade idea

[Amit]

I was doing some googling and it apears that the better welders have large capacitor banks in them.

I have a sip turbo mig 170 at home.. and also a couple of large 1F caps rated at 20v left over from my car audio days.. They are also available fairly cheapley of ebay and the like..

Would these help the mig? if so, how, and where/how would I wire it up?

Amit

 

[shenion]

MIGs run at 17-30V RMS (for 180A.) If you add a big cap it will filter to the peak value of 24-42V. Your low-V caps will promptly go poof.

If they would work, they would go after the rectifier and before the reactor coil. It will add a large surge at startup that will probably destroy the relay conacts. SIP's alread have relay failures as they don't use a proper contactor.

The cap will also increase the minimum output current considerably.

 

[GeorgeB]

If they would work, they would go after the rectifier and before the reactor coil.

So, with a single 50V electrolytic capacitor, does it go in line (in series) just before the reactor? The reactor is one wire in and one wire out, I assume.

With 2 capacitors, would the capacitors be wired in parallel?

How are they wired-in by Butters, Portamig and other MIG producers?

 

[shenion]

I have 2 30,000uf 80V caps on my CP-200.

The go across the rectifier output and are in parallel. I added them as this was originally a 3-phase MIG and I converted it to single phase.

It probably draws over 60A on the AC line when the contactor closes. I had to upgrade to a better 50A breaker as the cheap ones would trip. The MIG is 40A/3 phase so at single phase it is more.

Most are across the rectifier output. Better MIG's use SCR control rather than a contactor and they use zero-cross detection to minimize the surge on the line.

I would not try it on a cheap MIG as it will probably damage the diodes or relay.