Page 2 of 2 FirstFirst 12
Results 26 to 36 of 36

Thread: Running welder off generator?

  1. #26
    Join Date
    Sep 2012
    Location
    Knoxville, TN
    Posts
    859
    Post Thanks / Like

    Re: Running welder off generator?

    I am not an electrician or electrical engineer or welder designer or power-supply designer, but (I did stay in a Holiday Inn last night!) here is the conclusion I have come to, and maybe someone who is smarter than me can comment on whether it is right or wrong.

    People always talk about how "sensitive electronics" like computers must have a "pure sine wave" or "clean" output, such as is more typically created by an inverter-generator. I'm skeptical of this claim. If you think about a computer's power supply, the first thing it does is convert the incoming AC to 12v and 5v DC for use by the internals. Assuming the PSU is worth a darn, the PSU should be the only thing that will be affected by "dirty" power. But the components that go into building a PSU, like voltage-limiting diodes and stuff, tend to be pretty robust, and my hunch is that they are pretty resilient even in the face of "dirty" power.

    Will a transformer-generator be hurt by "dirty" power? In this case, the answer seems even more clear to me. A transformer-generator is built pretty much, if not entirely, from passive components (transformer, rectifier, inductor). It basically passes the mains AC straight out the welding leads--rectified in the case of DC welding. If the incoming mains signal is "dirty", then the welding arc may be affected, but again, it's hard to imagine how that is going to hurt the machine.

    An inverter welder, on the other hand, is more like your computer's PSU than like a transformer welder.

    When I think about the number one thing that is going to kill a PSU, it's not "dirty" signal. It's under- or over-voltage. You will burn up a voltage-limiting diode in a real hurry by driving it over the voltage it was designed for. Even if the diode can take the voltage, if it doesn't have an adequate heat sink, it'll fry. But over-voltage is never really the problem you're thinking about with a generator--it's under-voltage. The worst thing you are likely to do to "sensitive electronics", IMO, is run them in an under-voltage condition.

    Welders have a huge inrush current when you strike the arc. When the welder tries to draw this current, it bogs down the motor of the generator. If the generator cannot respond fast enough to get the motor back up to speed, then line voltage will drop, and you will get an under-voltage situation. In an extreme case, you just won't be able to strike the arc. I once tried to run my welder on 110v mains power through a 50-foot extension cord and had a similar situation. I could literally hear the welder's fan slow down when I tried to strike the arc! In less extreme cases, you may be able to strike the arc and keep it going, but weld quality will suffer, and more importantly, you may be constantly running your welder in a low-voltage condition. This will cause permanent damage--no question.

    When people ask me about running "sensitive electronics" off of a generator, first I give them the disclaimer at the top of this message, and then I tell them that my opinion is that as long as you keep your line voltage consistently around 110-120v, and your frequency around 60 Hz, you should be okay. Don't fret too much about "pure sine wave" power or not. You will hear a million stories on the Internet from people who say they fried their computer by running it off a non-inverter generator, but IMO, 99% of those people were really running off a generator that was too close to, or over, its rated load, and was running under-voltage, and they just didn't know it, because how many people run generators without bothering to confirm that the voltage and frequency are correct? Most of them.

    With a welder, there is no question that you must over-spec the generator to handle the welder's inrush current. This is more of an issue with transformer welders, which have a larger inrush, than with inverters. But IMO, as long as you have adequate generator capacity to handle the inrush, you don't need to worry about whether the generator is producing a "pure sine" output or not.

    That's my opinion. I'm open to corrections, but so far, each time I have shared it, even smart people who should know better than me have basically agreed.
    Everlast PA160-STH
    ... and that's about it!

  2. #27
    Join Date
    Sep 2012
    Location
    Knoxville, TN
    Posts
    859
    Post Thanks / Like

    Re: Running welder off generator?

    One more comment: why do you hear so much noise about "sensitive electronics" needing "clean power" to operate? Try this: next time you read an article about "sensitive electronics" needing "clean power" to operate, look at who the author is, or who their sources are.

    All of which is not to say that there aren't some issues with running some electronics off of "dirty power". Just that those issues tend to be over-blown (IMO) by folks who are selling "clean power" generators. How many people have run a laptop or desktop computer PSU off a "dirty power" generator for weeks at a time (e.g. people running at construction sites or outdoor concert venues) without any adverse effects whatsoever? A. Lot. So this whole "dirty power" thing must not be as cut-and-dried as it's made out to be.
    Last edited by joshuabardwell; 09-23-2013 at 02:02 PM.
    Everlast PA160-STH
    ... and that's about it!

  3. #28
    Join Date
    Sep 2013
    Location
    Upstate NY
    Posts
    2,356
    Post Thanks / Like

    Re: Running welder off generator?

    "Sensitive Electronics" are often just a way of saying "too small power supply"

    Computers and most comsumer elctronics run on low-volts DC. After passing through some filter capaciters.

    "Dirty" power is dropouts of 1 and 2 cycles or spikes beyond 200% of nominal voltage.

    A portable generator does not normally have these issues.

    However, for the purposes of running welding equipment, the amount of power available to the welder must not fluctuate significantly thruough the welding process.

    If the welder draws enough power from the generator to slow the engine or drop the voltage, the arc will be very unstable and create a poor weld.

    So, if you are going to need 4,000 watts to weld, make sure you have at least 5,000 continious available. Cutting things too fine will create an exrcise in frustration.

    Imagine driving a 8,000lb truck+load up a hill. You can do it with 300HP. But you will do it slow and be overheated at the top. With 450HP under the hood, you'll be better able to hold speed and won't destroy the engine.

    Always have plenty of power available when smoothness it required!
    Be wary of The Numbers: Figures don't lie,. but liars can figure.
    Welders:
    2008 Lincoln 140 GMAW&FCAW
    2012 HF 165 'toy' GTAW&SMAW
    1970's Cobbled together O/A

  4. #29
    Join Date
    Jul 2011
    Location
    Bossier Parish La.
    Posts
    5,824
    Post Thanks / Like

    Re: Running welder off generator?

    So, now we know what MIG you are wanting to run on this genset, but now you have answered your own question. I think the "step up" you are hearing is the engine loading up due to the resistance draw of the welder, just like adding lights, heaters or any other electrical load to the generator. This is normal function to hear. As far as the cycles goes, yours sounds a little low, unless it comes up to the 60Hz. rating under load. If not, then there should be an adjustment screw on the governor to be able to raise the RPM to bring the cycles up to 60 or close enough to it. You don't want to run anything for extended periods on lower cycles than it is designed for. Some things may not matter, like lights, but the electronics will benefit from having the cycles right on the generator. Like forhire said+/- 5%, but I would rather be more like 58-62 range. That is, 58Hz heavily loaded, 62Hz no load.

  5. #30
    Join Date
    Sep 2013
    Location
    MA
    Posts
    57
    Post Thanks / Like

    Re: Running welder off generator?

    Some very good info here. I will look in my generator manual to see if i can adjust the HZ. I agree with what you are saying joshua. I like the generator i have for running power outage situations because it is relatively small and efficient. I may want to think about something larger for my welding needs though. I eventually want to get a miller xmt anyway. maybe i can get a deal on some military style diesel gen. For now i will check the voltage and HZ under load and go from there.

  6. #31
    Join Date
    Sep 2013
    Location
    Upstate NY
    Posts
    2,356
    Post Thanks / Like

    Re: Running welder off generator?

    Just a reminder on the adjustments:

    The engine's speed determines the output frequency

    The governer's job is to keep the engine speed constant under changing loads.

    The electronics inside the generator determine the output voltage.

    So, adjust the governer for 60Hz (or as close as will hold) and then find and adjust the regulator.

    The sequence is important since the amount of power being sent into the generator also changes the output voltage.
    Be wary of The Numbers: Figures don't lie,. but liars can figure.
    Welders:
    2008 Lincoln 140 GMAW&FCAW
    2012 HF 165 'toy' GTAW&SMAW
    1970's Cobbled together O/A

  7. #32
    Join Date
    Aug 2013
    Posts
    25
    Post Thanks / Like

    Re: Running welder off generator?

    Quote Originally Posted by Broccoli1 View Post
    It is not that simple with loads like welders, motors etc
    sorry i have i guess been lucky using that math, just doing simple repairs where stuff wasn't welded right to begin with
    most of the time the company had generators or i rented them ,i have used some small dinky cheap things for work under hundred amps mainly around 60 amps. i know that the start is the hardest draw so i always went for the max of the machine rating and it worked...

  8. #33
    Join Date
    Sep 2013
    Location
    Upstate NY
    Posts
    2,356
    Post Thanks / Like

    Re: Running welder off generator?

    Quote Originally Posted by gypsywanderin View Post
    ... i know that the start is the hardest draw so i always went for the max of the machine rating and it worked...
    So, you calculated the MAXIMUM draw you welder could do and chose a generator that would provide at least that much power?

    That'll work great while you are under 75%-80% of the maximum capacity of the welder (99% of the jobs).

    If you just happened to need to run your welder near it's maximum potential, your welds would suffer as the engine bogged down und the load.

    Like you said, "...lucky using that math,...", but when you start getting near the boundries, the work will suffer.
    Be wary of The Numbers: Figures don't lie,. but liars can figure.
    Welders:
    2008 Lincoln 140 GMAW&FCAW
    2012 HF 165 'toy' GTAW&SMAW
    1970's Cobbled together O/A

  9. #34
    Join Date
    Dec 2007
    Location
    Los Angeles
    Posts
    8,225
    Post Thanks / Like

    Re: Running welder off generator?

    Quote Originally Posted by gypsywanderin View Post
    sorry i have i guess been lucky using that math, just doing simple repairs where stuff wasn't welded right to begin with
    most of the time the company had generators or i rented them ,i have used some small dinky cheap things for work under hundred amps mainly around 60 amps. i know that the start is the hardest draw so i always went for the max of the machine rating and it worked...
    No problem- if someone already has a generator might as well try it but when someone asks about which generator to purchase then we try to size the generator so that it isn't underpowered for its life
    Ed Conley
    http://www.screamingbroccoli.com/
    MM252
    MM211 (Sold)
    Passport Plus & Spool gun
    Lincoln SP135 Plus- (Gone to a good home)
    Klutch 120v Plasma cutter
    SO 2020 bender
    Beer in the fridge

  10. #35
    Join Date
    May 2015
    Location
    Great Lakes, IL
    Posts
    6
    Post Thanks / Like

    Re: Running welder off generator?

    I know this is an older post, but did you continue running your Miller 211 of the generator?

  11. #36
    Join Date
    Jun 2012
    Location
    Laredo, Tx
    Posts
    5,759
    Post Thanks / Like

    Re: Running welder off generator?

    Quote Originally Posted by Drphone View Post
    I know this is an older post, but did you continue running your Miller 211 of the generator?
    I just tried out my Millermatic 211 on my Troy-bilt 7k/10.5k generator that supposedly has < 6% THD. On the 20A outlet, I could go to 3/16" Auto-Set setting and keep the panel output (the wired receptacle with four 20A 120V outlets) to ~91% on the in-rush, and 2sec later it would steady-state in the mid-high 80% depending on how steady I could hold the mig gun arc length blindly, lol. I didn't try the 240V outlet because I haven't wired up the 4-prong twist lock to a standard 6-50 receptacle.
    Last edited by Oscar; 12-26-2015 at 04:01 PM.
    1st on WeldingWeb to have a scrolling sig!

    HTP Invertig 400
    HTP Invertig 221
    HTP ProPulse 300
    HTP ProPulse 200 x2
    HTP ProPulse 220MTS
    HTP Inverarc 200TLP
    HTP Microcut 875SC

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Page generated in 1,627,860,704.23771 seconds with 11 queries