Help choosing 240v generator for MIG welder?

   / Help choosing 240v generator for MIG welder? #31  
Like Bukitcase, I have not scoped a generator but ever notice that small engines are usually governed to 3600 RPM. Directly spinning a generator = 60 Cycles \ sec (60Hz). I have a 7500peak 6250 running on a 13HP engine. Using the so called 30 amp 120Volt plug powering my SP125 (use it at home on a 20 amp circuit though spec is for 25 amp) the generator will pop a breaker from time to time. Probably comes down to quality of generator so do you buy a cheap 10K or an expensive 7.5 K?
 
   / Help choosing 240v generator for MIG welder? #32  
Like Bukitcase, I have not scoped a generator but ever notice that small engines are usually governed to 3600 RPM. Directly spinning a generator = 60 Cycles \ sec (60Hz). I have a 7500peak 6250 running on a 13HP engine. Using the so called 30 amp 120Volt plug powering my SP125 (use it at home on a 20 amp circuit though spec is for 25 amp) the generator will pop a breaker from time to time. Probably comes down to quality of generator so do you buy a cheap 10K or an expensive 7.5 K?
Good comment Dave... I learned to buy quality if I wanted to use it for more than a few times.
 
   / Help choosing 240v generator for MIG welder? #33  
Make sure you get a genny that has less than 5% THD, if you want to run a PA200 (or any electronics) on it. Ask Mark about it.
 
   / Help choosing 240v generator for MIG welder? #34  
Where do you find that info per a generator? I've been looking at various makes/models and cannot seem to find %THD listings anywhere? Should they be listed in the machine specs? What am I missing? Thanks for pointing me in the right direction if you can. Greg
 
   / Help choosing 240v generator for MIG welder? #35  
If it does not advertise it, it is not going to be clean...usually. That is a major selling point, and any generator company that doesn't state that it is clean, IF it is clean is loosing sales to others that do.

So if you don't see it stated, don't worry with it. Usually inverter generators are clean power. Most if not all of them first generate 3 phase power before it is "inverted" into a clean sine wave.

Total harmonic distortion % sometimes can be found in the manual specs or pdf/brochure specs. Or you can call the customer service line and they will tell you if it is a company worth their salt.
 
   / Help choosing 240v generator for MIG welder? #36  
Okay and thanks Mark. I wasn't sure if I was missing looking someplace special; I thought it should be listed within the specs, but it wasn't on the gens I was then looking at.
Also - I'm a bit of a dummy I guess - but, I don't really know what an "inverter" means/is. Could you sorta splain it some. I know that my Lincoln arc welder is an old transformer welder and I'm quite impressed by the PA models just don't understand the inverter reference. Greg
 
   / Help choosing 240v generator for MIG welder? #37  
Inverter generator or welder? There are both. I even have an inverter microwave.

Layman version as best as I can make it. Inverters take AC power, and break/chop it down into tiny pieces of DC power and then reassemble it into the wave form with the use of diodes/rectifiers and transistors (usually Mosfet, IGBT, or some sort of thyristors). In essence a big filter that lets power only pass in one direction instead of changing polarity. Most AC/DC welders that are transformers use some sort of rectifier to achieve DC power. Think of an AC sine wave then chop the tops off the sine wave close to the top and discard the rest. Then the top of a long sine wave resembles a long, flat dotted line...which is essentially DC but with some gaps. Most inverters goes further. It chops the tops and bottoms (positive and negative parts) off and "inverts" them to fill in the gaps somewhat. The transistors then takes this and reassembles this wave, into a straight (er) wave form switching at 10's of thousands cycles per second. It is usually then run through some "conditioners" such as capacitors, small transformers or special coils that smooth the DC out even further and creating even more of a straight line. Or it can take this DC wave and turn it back into AC sine wave that can be adjusted to any desired frequency (within reason). All of this is electronically managed of course.
One point I'd mention is that whether an inverter or transformer, you really don't have a 100% true DC straight line "wave". It's chopped up into many tiny little pieces of DC power. It's sort of like having a long line that at regular resolution looks solid, but as soon as you start putting it under a magnifying glass, you can see the tiny little breaks between each part of the line.
The difference in a rectifier system on a transformer welder is the smoothness of the DC and the shape of the AC wave form. The rectifier of the transformer has only 60 cycles per second to operate on and it leaves larger gaps between each component of the sine wave. An inverter provides cycle times is several hundred times faster than that, which can create a smoother, less noticeable gaps in the DC output. A DC generator like an SA 200 works off even a more pure DC output because of it's design. Some of your cheaper modern engine drive welders (cheaper ones) use an alternator basically and then convert it to DC for DC output.

An inverter generator produces AC power first, in 3 phases. The more phases used, the better the quality of power will be put out because there are more sine waves to work with creating a more consistent line of DC that can be converted back into a stable AC output.

This probably got a few errors in it as I am not an electronics engineer...
 
   / Help choosing 240v generator for MIG welder? #38  
Ooookaaay Mark, Like you - I am in no way an electrical engineer - but thank you much for laying it out in somewhat layman terms.

I did a search using "inverter - what is" - and got a shaky understanding of the idea after I'd already posted my question. So thanks for further clearing my cloudy head.

In reality, I have no clear understanding of the function except that they (inverter welders) come in a "small" package and can pack as much punch as an older model buzz-box for example. After I purchase an acceptable (less than 5% THD) generator to power my current AC 225 Lincoln stick welder, I will be in touch to inquire about a PA200 or PA300. I do like the idea of being able to use either 110 or 220 as a power source. Although my limited experience with welders has been with 220 powered buzz-boxes and stick welding thick metal.

I just wanted to glean some idea of what an inverter actually does and how it manages to do it. Thanks, Greg
 
   / Help choosing 240v generator for MIG welder?
  • Thread Starter
#39  
Greg, how many amps do you want to weld with? If you need the full range (225) you may need something like 11,000 watts.

It's my understanding that with about 7200Watts you can weld at about 150Amps. For my needs I'm planning on 8000W , maybe 10,000w generator. I'm not too worried about THD because the Miller tech said my MultiMatic 200 (an inverter welder) can tolerate almost any power source. He said any generator over 7200Watts will run the MM200 at the full power settings. Thats just my miller, I cant make any guesses about other inverters.
 
   / Help choosing 240v generator for MIG welder? #40  
After I purchase an acceptable (less than 5% THD) generator to power my current AC 225 Lincoln stick welder, I will be in touch to inquire about a PA200 or PA300. I do like the idea of being able to use either 110 or 220 as a power source. Although my limited experience with welders has been with 220 powered buzz-boxes and stick welding thick metal.

I just wanted to glean some idea of what an inverter actually does and how it manages to do it. Thanks, Greg

Greg, generators to run your Lincoln buzz box have to be big - to run an inverter they can be much smaller.
I run my Maxstar 150s inverter off a 5000/6250 generator for example.

But here is what Lincoln says about running the AC 225:

"It does appear (if you do the math) that you should be able to use 1/8 in. and smaller diameter electrodes with an AC/DC 225/125 powered by a 5000 or 6000 watt generator. Unfortunately, the design of the transformer on the AC/DC 225/125 is not efficient enough to be powered by a small generator. If you try and weld with this combination you will most likely experience the electrode being hard-to-strike and also the electrode frequently sticking to the work.

If you are fortunate to establish an arc, the arc will tend to pop out frequently. Also, there will not be adequate heat input to the work, resulting in low weld quality (poor fusion), and poor bead appearance.

To successfully run your AC/DC 225/125 welder you would need a minimum of a 15,000 watt AC generator."
 
 
Top