Do I need an inverter with my 7000 watt generator

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I have a Thermal Arc Fabricator 211i 220v 30 amp welder and I need to be able to run it off of a generator. My understanding is that a good rule-of-thumb is to use a generator that provides at least amps x volts' worth of wattage. In my case thats 30 x 220 which is 6600 watts so I'm looking for a 7000 watt generator.My question is - do I need a pure sine wave to run the welder? In other words, do I need an inverter on the generator output? Or can I just use the 'modified' output the generator produces?I am a hobby welder, a 'weekend warrior' -  I don't work with welders and I'm basically a beginner. I cannot run this off the electrics because the landlord won't let me.I appreciate any advice on this
Reply:According to nearly every manufacturer you should only run their welders on Pure sinewave. But I hear of people using modified with no problems just don't say anything if you ever need to sue the warranty.
Reply:What generator are you looking at that has a modified sinewave? If you are looking at the inverter style generator  Why not look for a simple standard rotary one that put a normal sinewave in the first place? Here is something about generator that most do not realize that the inverter style ones are a DC generator that use an inverter  to make 220 volt or 110 volts. Just like the newer welders do. Except they do the opposite taking dc voltage and producing ac voltage.Klutch 220si mig , stick, and dc tigHobart 140 AHP ALPHA 200X 2016Lotos LTP5000DSmith O/P
Reply:Originally Posted by tinker001What generator are you looking at that has a modified sinewave?
Reply:Dunno about your generators in the States, but 8Kva units hear usually run dual 15amp outlets (@ 240 volt) and have built in RCD's . This is a good starting point for any industrial use, smaller and it will likely be only 10 amp outlets (which will hardly run a hobby welder) and you will have to put your own RCD in line, so most everyone wanting a serious generator goes 8kva. Might be a similar threshold in your market?For example I have a 3.5kva unit, that theoretically should run my hobby welder easily, (240 volt 10amp) - not a chance. I wouldn't even look at connecting my go to welding unit (240 volt 15amp).   I rent an 8Kva generator when I need remote power and it is beautiful compared to mains power! It's like my welder is worth another $1000 bucks in quality!
Reply:Generally speaking and IMO, the generator should be sized larger than the max kW consumption of the welder to prevent wild voltage dips.  Most welders should state an "Imax" or "I-inrush" amperage.  Kinda like how a heavily loaded compressor motor temporarily needs more to start up than when running---well same for welders, but not as severe.  If a welder consumes 30A @ 230V at full-tilt, it may need closer to 35-40A if the arc initiation is at full-tilt at the instant welding begins.  I have a Troy-Bilt 7000W generator, that I don't use for running my welders.  But I did choose it because Troy-Bilt claims less than 6% THD even though it is not an "inverter" type generator.  That said, I did try out both my HTP 221 and my Miller 221 inverter welders on it, just for the heck of it.  I'm just a hobbyist (and probably a dumb one that that to take the chance ), but both worked just fine.  Although I didn't run them full-tilt, I think it could handle it with 10.5kW of peak output capability. 1st on WeldingWeb to have a scrolling sig! HTP Invertig 400HTP Invertig 221HTP ProPulse 300HTP ProPulse 200 x2HTP ProPulse 220MTSHTP Inverarc 200TLP HTP Microcut 875SC
Reply:I may be crazy but I have probably put an hours worth of welding with my 211i on a Champion 7500 generator and no problems. The Tweco runs perfect on the generator power.Thermal Arc 210 - Tweco 211I - Cutmaster 52
Reply:You need a generator that has 25% more than your welder at max. This their rated continuous output but not the max output you have to look at specs not advertised output. For instance a 7000 watt peak is the max that it could produce  for 10 to 30 seconds. In realty it would only do 5000 watt on a continuous output.   You need to do some serious reading about the items that you are putting together to see what is you can use what ti stay away from.Klutch 220si mig , stick, and dc tigHobart 140 AHP ALPHA 200X 2016Lotos LTP5000DSmith O/P
Reply:I have the troybilt 7kw and it runs my old miller spectrum 625 on all but the max setting.old Miller spectrum 625 Lincoln SP-135 T, CO2+0.025 wireMiller model 250 and WP-18V torchCraftsman 100amp AC/DC and WP-17V torchCentury 115-004 HF arc stabilizerHome made 4 transformer spot welderHome made alternator welder
Reply:I run a 252i and a Miller Maxstar on a 10kw generator (not at the same time) I have no power limitations and can run them both full power if needed. My cutmaster 52 plasma I run max at 50 because I have a compressor going also. I don't think you will have any problems but spend some money on a good generator with as clean of power as you can find and one that will put out real power not just surge as other have said. My generator is actually rated at 9500 even though it's advertised as a 10kw.I forgot to add my generator has less than 5% thd advertised if that makes any differnce.Last edited by Jawslandshark; 03-29-2016 at 01:08 AM.ESAB Rebels 215 and 235, ESAB HELIARC 281i, ESAB ET 301i, Hypertherm 85 and 45XP, Thermal Arc 185, TD 60i, HTP PRO PULSE 300