what is the difference

[PWTEngineering]

between the ls 200p and the 200pi?

[WookieWelding]

the p is mosfet technology
the PI is IGBT Technology

[gilly]

I would choose the 200PI if contemplating buying one or the other.

[LONGEVITY]

To sum it up, IGBT chips can handle higher voltages and are seen in the top leading manufacturers. Our PI models use IGBT chips and our discontinued WeldAll 200p featured MOSFET technology.

Our on live site there is an article about MOSFET vs IGBT

IGBT Welder | Longevity Welding Equipment.

[tigqk]

The IGBT cuts down on the number of long tailed mosfets needed on a board and can handle power better than the mosfets can from 250-1000volts, but don't right off the old mosfet technology yet because mosfets are better than IGBT's at high frequency switching.IGBT's are also more robust in handling of transients and hard switching errors.From a mfg standpoint it probably is more expensive to use IGBT's but you have less DOA's from shipping hazards as their are less components to deal with.
I have the Weldall 200PI multifunction(mosfet) and love the machine and could not be with out it and the 256 PI will be my recommendation, I have seen the cuts made with IGBT version of 200Pi and they are more consistently powered in my veiw.