Plasma cutter powered by generator?

[lynx85]

Not really knife related question, but I hope you all can help me. I am looking to buy plasma cutter, mostly for farm work, to be specific - demolition. I started to build my own hydraulic press last year and during that process I realized I have quite a lot scrap metal. Not to mention, plasma cutter would really be useful in that press project.
I have looked some time for make/model what I can buy locally (Eastern Europe, Latvia), used and new. I want 3 phase 380V, because I have some old tractors, truck frames etc., where inch+ thick cut is almost half the job. I'm looking up to 70-80amp cutters. With all that in mind - my home electricity is 25A 230V, and I have 3phase 8kw kubota diesel generator and 3 phase 17kw diesel generator trailer. I would power plasma cutter from one of my generators and air compressor from house, since that is how I used compressor all the time and that works. Is it reasonably to expect normal plasma cutting work if power comes from generator? What are the weak links to look, before buy anything? Have never had plasma before. Transformer type or inverter? I looked about generators, automated voltage regulators, I think my generators don't have that. Well, maybe smaller kubota has, it's made in 2006. Bigger one is from 1983, so, safe to say it is without fancy electronics. What else I don't know and should look into?

 

[Stacy E. Apelt - Bladesmith]

Your generator may be a bit too small. An 80-amp plasma cutter running from 380V three-phase split into 240 volts (two legs) draws 72 amps current ... which is 17.3 Kw. Most generators are rated at full power startup current and only deliver a continuous current of about 80% of the rating.
It will probably work if you don't do long burns, but the generator breaker may kick out occasionally. Another issue is that a generator may be rated 17Kw, but that is split between the various outlets. My 16Kw/240V generator has a 50-amp outlet as its largest available power (12Kw). My 40-amp welder will occasionally kick the breaker on the generator.
Your generator may be different.

 

[lynx85]

I look for true 380V cutters, as for example this one - https://www.netbid.com/images/13824/V13824-57_2_slide.jpg?w=569&h=427&404=default
Max draw 28Amp, at full power. This is european 3 phase, I don't really understand phase split and two hot legs because that is not our system. For ratings and difference between kva and kw I know. But I also have heard mentioning that generators are "dirty" power - is that voltage or frequency fluctuations? Or is all problems just because people try to run industrial machines from garden generators?

 

[JV Knives]

I look for true 380V cutters, as for example this one - https://www.netbid.com/images/13824/V13824-57_2_slide.jpg?w=569&h=427&404=default
Max draw 28Amp, at full power. This is european 3 phase, I don't really understand phase split and two hot legs because that is not our system. For ratings and difference between kva and kw I know. But I also have heard mentioning that generators are "dirty" power - is that voltage or frequency fluctuations? Or is all problems just because people try to run industrial machines from garden generators?

The “dirty” power thing on non-inverter style generators results in an inconsistent electricity flow that some sensitive electronics do not like. Example: cell phone charging not recommended for them…I’ve charged my phone for them many times. If it blows , shame on me. I don’t think that will have so much impact on a plasma cutter. By nature, most plasma cuts are “rough cuts” so I don’t think fluctuations will matter much at all as you blow away molten metal. If your units has a sensitive control panel that may be another issue.

My 2 cents
John
JV Knives

 

[lynx85]

That's the case - I don't know how bad is electricity from generator and how sensitive is plasma cutting units. Water pumps run just fine, light and heating too. Not that I used them much, my smaller generator is backup for farm work when mains are off, biggest one - well, I just got that, like much else in the farm.
If I buy new plasma cutter, then there really is just inverter type machines available. With lcd displays and such - should I consider them sensitive? Or look for transformer type, even if all units available locally are used? Or buying used, especially for first plasma cutter, is dumb idea?

 

[A.McPherson]

If it's an older transformer type, it's probably fine to use with a generator, but I wouldn't use a newer inverter style one. Lots more sensitive electronics...