welders an run off generators?

[jtybt]

Just had a thought. Are the inverter type welder able to be used off a generator. How about the new solid state circuitry etc and generators?

[performance]

The units can be run off generators. However, with that said, a quality sine wave must be provided. Mike can chime in on what he thinks is best, but a squarewave won't do it I don't think. There are generators out there that are clean enough to work just fine, especially the newer engine drive generator welders from Miller and others.

[jtybt]

I have an old Sears, alternator gas generator(2000 amp) would that work?

[performance]

You'd probably need to get it tested for phase performance and checked on an oscilloscope for correct wave characteristics. I would doubt that it would though, but you never know.

[use2farm]

A engine powered generator produces a pure sine wave. No problem there.

I have run my Power Tig 250EX and my Power Plasma 50 off of my 7000 watt generator exclusively except for maybe 2 hours when the welder was connected to the power grid.

I will say that 8 kw. would be better at the full output of the 250EX.

A 2000 watt gen set will output about 16 amps at 120 volts and half that at 240 volts. That would only power the smallest of welders.

[performance]

No,

Unfortunately they don't. There's a lot of variables that go on with that, but they don't. Not even the power company produces a 100% pure sine wave. Even name brand generators don't always do it. A lot of them produce impure or dirty sine waves with a lot of interruptions or a pure square wave.

Another issue is actual voltage output. Some generators fluctuate in their power output. A few rpms can make a huge difference between 240V and 200.

But here are a couple of links you might find interesting:

http://www.jkovach.net/projects/powerquality/
http://www.millerwelds.com/resources...=story109.html

Maybe we need a thread of our own discussing the pros and cons of portable generators. Even our own generators do not produce a good sine wave acceptable for some kinds of electronic equipment with out a filter.

A word to the wise: Running our welder or any electronic inverter on an untested, uncalibrated generator can cause harm to your machine. And in such case the warranty may not be honored. Of course, this will speak volumes about the customers honesty level....Who will know? But we have our ways...lol....Really please don't run your unit on a suspect generator. As long as the sine wave is good, I don't have a problem. But to plug it into an unknown unit...I do have a problem with that.

This goes also for under powering your welder with a generator not capable of producing enough wattage to handle the load or a "loping" or unstable generator that is not capable of producing fairly constant power within our welders 10% limit. Though using it in a lower range is fine, it is hard to determine exactly what you are pulling in amps. Heavy loads also reduce engine rpms which reduce voltage.



A simple way to figure out if your generator will match your welder requirement, is V X's A = Watts. So for a 250 EX which draws a MAX inrush current of 45 A and a 220 V input would look like this 45 X 220= 9900 watts.

So a 250EX needs 9900 watts to operate properly at a wide open start. Though its normal operating amperage is only at 36A, or 36X220=7920watts, it can demand a generator to supply up to the max watts depending upon the load on the welder.

Any way you look at it, 7k is low. I'd feel comfortable operating my 250EX on my Lincoln Ranger 8 as it can go to 8500 watts, as I wouldn't ever operate it wide open anyway, but a new Ranger 10000 or Ranger 250 or Miller Bobcat 250 is better since the produce over the 10k requirement.

The older G7 Lincolns are a little short on power and they did not produce good power for operation by and large, though I have heard a good going over will bring them up to speed.

[Jeepster0000]

Okay guys, I am sorry to resurrect an old thread, but I have some questions.

I own a miller bobcat 225 welder generator. It does a great job of welding and makes a fantastic generator. The rated output is 8500 watts continuous and 11000 watts peak. I do do not own an Everlast product yet, but I am looking to purchase one soon. I have been looking at the Everlast 250ex powertig unit.

I do some portable welding and would like to incorporate a tig into my toolbox. I know what the last posts have said, but can I run a powertig 250ex off my bobcat if I do not go to max amps and do it with out ruining my tig unit?

I am hoping that I can, if not, I am going to have to sell my generator to buy my tig unit, then I am going to save up for a new trailblazer diesel. I am hoping I do not have to go though all of that.

Thanks for you replies,
ADAM

[Ray]

Well I thought I’d jump in here as I run Everlast products off generators a lot.
What I’m using most is a Chinese made gas gen set. I’ve ran a PowerPlasma 60 of a Bobcat as well, worked great.
Here’s some of what I know or have learned over the years.
Most fairly modern gensets produce true sine wave single phase power. With the frequency controlled by engine rpm via the governor. The exception is the inverter units, they produce square wave power (like the welders) frequency controlled electronically. Inverter generators are very efficient but due to the square wave there is more RMS voltage, not going to get into a big technical discussion about this here but generally this puts a strain on the power supply of any electronics and is not recommended.
The Voltage on a normal genset is controller by a voltage regulator connected to the field windings, and are adjustable. However seem to always be set to 250 Volts, I assume to squeeze as much surge power as possible out of the units, most things will run fine with a little overvoltage. The Everlast units are designed to run off 220 – 240 V. So I generally adjust the AVR to 240 volts , or as close as possible, then adjust the frequency (engine warm under a load) to as close to 60 Hz as possible. This is where a Diesel genset shines, the larger flywheel will help smooth out the transitions when putting on a load better than a gas unit.
Other than the initial (arc) start the voltage and freq seem to remain pretty constant as long as everything is working right (warm engine, clean gas etc.).
If stating a Plasma Cutter I found it useful to start with a little lower amp setting until you start then ramp it up, otherwise you might get a false start with the pilot arc. Tig you normally ramp it up anyway. Stick and mig just be prepared to have a second or so at first to let everything stabilize.
Now, Knock on wood, haven’t damaged anything running them off the generator, maybe Mark or Mike have had deferent experiences. But I think it’s OK as long as you have a big enough set, and it’s kind of like welders bigger is usually better. The one I use mostly is 7KW. But I had no trouble with the Bobcat at all.
Not trying hold myself out as expert on Generators , just the school of hard knocks, and field work.

[performance]

Any welder generator built in the last few years should be fine. Older ones may not.

Still, a lot of discussion can be found about generator quality on the net. But if you'll see companies like Generac, you'll find that they have units that they admit are not acceptable for electronic items. They sell a higher priced unit that they say is "safe".

[Jeepster0000]

Ray and Mark,
Thank you for the fast replies, I am looking at purchasing the TIG welder in the next month or so. I have been reading a lot about the power output of the bobcat vs trailblazer vs ranger. I do a lot of welding off the bobcat, and have had no issues with it, so I just want to expand my capabilities with the TIG.

My welder / generator was built in 2001, is that too old? Now the big question, should I keep the bobcat or sell it to get a trailblazer or bobcat diesel? Or, should I keep the bobcat, and run it off that? Remember money is an option!

Thanks
ADAM

[everlastsupport]

You have a couple things to deal with when running a solid state welder off a generator. In rush current, ramp up and a clean running sine wave.

If the unit you have is 8500 watts, that's enough power to run a 200 amp TIG (35 amps of power). If your unit has a clean sine wave, but no AVR, you can start the amp low and ramp it up via the 4T or foot pedal. Automatic voltage regulation (AVR) is key in starting the unit, but a good sine wave is more key far as damage to the power supply.

Call Miller and ask if the Bobcat will run their new solid state units. If they give you the go you're probably fine.