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jtybt
02-18-2010, 10:16 AM
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
02-18-2010, 04:12 PM
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
02-18-2010, 06:19 PM
I have an old Sears, alternator gas generator(2000 amp) would that work?

performance
02-18-2010, 06:30 PM
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
02-18-2010, 11:57 PM
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
02-19-2010, 12:35 AM
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/articles/index?page=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.

everlastsupport
02-19-2010, 01:34 AM
Mark's right as well as Use2farm.

You need a lot of power for the inrush to fire a units up. Enough power will make it work (power = watts). But I would recommend a good clean sine wave as well. That's not most generators on the market.

An old water pump is not a solid state welder, but the water pump will handle the weak inrush, so will an old transformer buzz box.

If you have a true alternator/generator (not an inverter) that can produce the power and no major drops on the initial load you will be fine.

use2farm
02-19-2010, 04:29 AM
Let me see now. You say that my 7kw (continues) 9kw inrush is too small for my 250EX at full power, which I donít use it at. Typical amps are 35 to 170. Also now I find that your warrantee may be void because I did not first have my generator certified by a generator God or who ever does that sort of thing.

Perhaps I have made a mistake by not buying Miller in the first place.

By the way, the first link is mostly about modified square wave inverter power supplies (UPS) and such. The engine driven generators all outputted true sine waves. Admittedly, some have more ripple then others as shown.

I am a retired EE, owned my first oscilloscope in 1948 or 49, have used the ohms law once or twice and I am older than dirt.

And that is all I have to say!

everlastsupport
02-19-2010, 12:04 PM
Let me see now. You say that my 7kw (continues) 9kw inrush is too small for my 250EX at full power, which I donít use it at. Typical amps are 35 to 170. Also now I find that your warrantee may be void because I did not first have my generator certified by a generator God or who ever does that sort of thing.

Perhaps I have made a mistake by not buying Miller in the first place.

By the way, the first link is mostly about modified square wave inverter power supplies (UPS) and such. The engine driven generators all outputted true sine waves. Admittedly, some have more ripple then others as shown.

I am a retired EE, owned my first oscilloscope in 1948 or 49, have used the ohms law once or twice and I am older than dirt.

And that is all I have to say!

If this was to aimed at me.

First scope was in 1977, BSEE also. It was a Tektronix 314, nothing as nice as the ones we had at work though.

My response was to a post that said 2000amps and I assumed (and we know what that means) they meant 2000 watts, that is too small.

I'm not sure why you state you use your Everlast products off a 7kw unit, so I would think you are happy, but then state maybe you should have bought another brand?

performance
02-19-2010, 02:21 PM
I recognize the first few were UPS devices, but that wasn't the point of my post.

Miller does not recommend the running of their units on dirty power either. Show me any literature that states they do. They had issues themselves. If you are running one of their welders with a dirty generator and they find out about it after a fail, you will be holding your head between your hands. I am not saying our machines won't run with less than perfect power, but they are sensitive electronic equipment, essentially a computer.


Being in the welding industry myself, I can tell you there is a lot of private discussion regarding the use of inverters on generators. This has been an issue and its my responsibility to stay up on top of the ball with it. The trend is that a lot of guys are starting their own portable repair businesses and trying to do it on the cheap by buying a small inverter welder and using a generator to power it. Its a smart idea, if the generator is a quality generator.

But a lot of generators now are inverters so the danger exists that it can cause damage.

Rodsmachineshop
03-01-2010, 05:31 PM
Hooked a smaller plasma cutter I had to a 12000 k gen and my plasma fried itself , so I will never hook anything like a welder or plasma cutter to one ever again The gen was a good quality generator . had a friend fry his mig welder a couple of month ago also on large onan he learned just like me don't do it.






Let me see now. You say that my 7kw (continues) 9kw inrush is too small for my 250EX at full power, which I donít use it at. Typical amps are 35 to 170. Also now I find that your warrantee may be void because I did not first have my generator certified by a generator God or who ever does that sort of thing.

Perhaps I have made a mistake by not buying Miller in the first place.

By the way, the first link is mostly about modified square wave inverter power supplies (UPS) and such. The engine driven generators all outputted true sine waves. Admittedly, some have more ripple then others as shown.

I am a retired EE, owned my first oscilloscope in 1948 or 49, have used the ohms law once or twice and I am older than dirt.

And that is all I have to say!

performance
03-01-2010, 05:54 PM
The quality is in the wave, and voltage output not the brand. Name brands aren't always what they appear.

Rodsmachineshop
03-02-2010, 05:36 PM
Thats true . I have a freind that ownes a large welding bussness and he uses his tigs and other welder on generators , I asked him about generators and he told me he only use diesel generators since not so noisy and produce a smoother power wave and use less fuel. also there rpm dont change much under load. he also uses a generator double the amps requird to run welders .

Jeepster0000
08-27-2010, 07:56 PM
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
08-27-2010, 09:56 PM
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
08-27-2010, 11:09 PM
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
08-28-2010, 06:18 AM
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
08-28-2010, 12:22 PM
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.

Ray
09-01-2010, 01:03 AM
Jeepster,

If you do contact Miller I'd be curious what theyíre response was.

Ray

Jeepster0000
09-02-2010, 01:30 AM
I did contact Miller. He said that my year of bobcat will be good to run the miller dynasty 200 and any other solid state units like a plasma cutter. Though he did stress that I should not run the dynasty 300 off of my unit.

But I think the Everlast Tig should run great :D

everlastsupport
09-02-2010, 02:02 AM
Well, the 300 will pull more power. If the generator can hold with AVR 40 amps. You should be fine.

sschefer
10-22-2010, 02:35 PM
A generator that is not designed to be a generator for a welder or a generator that is not incoroporated in to a welder like the Bobcat or Ranger are not good choices for running a welder unless you are very critical about the generator that you buy.

Generally, an inexpensive generator (under 4000.00) that has no load/load rpms (wattage ratings) is not the best choice. The RPM of them motor determines the frequency of the phase and at no load it could be as low as 30 cycles per second on some of the inexpensive models. I deally you would like noload/load condition to be at 58-62 cycles per second. Most good gen sets do not actually increase RPM but instead they increase developed shaft HP to maintain a constant RPM.

An inverter TIG requires very little current when it is not welding. The minute you strike an arc the current demand is instantly much greater and the generator will still be in a no load condition. The time it takes for it to ramp up to meet the current requirement will be a period of insufficient voltage and current will rise rapidly resulting in excessive heat and unit failure.

I think if you look at the Miller and Lincoln, they have welders that can be run on generators but they also state the wattage requirement. Ideally, the minimum wattage (no load) should be adequate (P=IxE) to meet the startup input power requirement of the welder. In otherwords, for a 250EX to be run off a generator the no load current needs to be somewhere between 0-100amps. The welder is a 220v and if it ever started with a 100amp requirement you would need a 22,000 watt generator and that's 22,000 watts in the no load. (P = 100x220)

As was mentioned before, you could us the ramp up/ramp down feature of the welder, if it has it, in order to decrease arc start input current requirements but you're playing a guessing game as to wether the generator can ramp up quick enough and where the upper end of the low limit would fall.

I've left out a lot of the particulars because this post would be way to long to read if I detailed it all out.

My advice would be to buy a welder generator and leave the inverter in the shop. Besdies, TIG welding outside is a hard way to make a living. The setup time eats up all your labor profits and people just won't pay you to do it.

footboarder
03-02-2011, 08:05 AM
Years ago I worked near the film crew for 'Runaway Train'. The cycle was so important to them that they welded rigs on the side of the locomotive not visible to the camera so they had platforms to mount their own generators for the moving scenes lighting. These generators had a 'cycle' control and maintainer. This was so important to the film crew because the cycle affects the temperature of the lights (Kevins). This in turn affects the color (Techicolor) as to how the film (negative) reads it. I imagine a rectifier machine is not using DC only. Especially when it is a AC/DC machine. Even a straight DC machine may have controls on the AC side that are affedted by the 'cycles'.