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Thread: Welding using a gen set.
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22nd Aug 2018, 08:18 PM #1Novice
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Welding using a gen set.
Hi Guy's,
Was curious if any of you have had good success in using a non inverter arc welder on a non inverter gen set?
I tried a few different arc welders on a 8KVA Honda powered gen set, but overall a poor result I thought.
Arc hard to start and would cut out, even sound and look not the same as grid supply.
From the results I would assume it was doing the gen set no favours also.
Live and learn.
Trev
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22nd Aug 2018, 08:46 PM #2Pink 10EE owner
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8kva should be plenty to run a small ~140 amp transformer single phase stick welder.
We used to run them on 5kva dunlites.Gold, the colour of choice for the discerning person.
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22nd Aug 2018, 09:26 PM #3Novice
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The welder runs but it's a different machine on the grid.
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23rd Aug 2018, 10:07 AM #4Most Valued Member
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You are dead right. I have done a fair bit of welding off generators with transformer machines and my observations have been that the quality of the gennie makes a difference, the quality of the welder also has a large bearing, arc starting will be harder and they do not perform as well as there simply isn't the reserve capacity in a generator that the grid has. I generally stuck to 2.5mm electrodes where possible unless I had a really good generator and welder. It pays to remember that momentary spikes in primary current can be as high as 90 odd Amps when running 100 Amps welding current with a transformer machine and that takes a lot of gennie and a fast reacting governor and voltage regulator to handle.
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23rd Aug 2018, 10:26 AM #5Diamond Member
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Might be worth trying an inverter welder? The 140 amp units are pretty cheap.
I was able to run a 2.5mm rod at around 60-70 amps off a cheap-arsed Bunnings 2kVA genny, although I had to try a few times to get a very "gentle" arc start otherwise the breaker would trip.
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23rd Aug 2018, 01:33 PM #6Novice
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Thanks Karl,
The spikes would also be killing the gennie.
When you mention a really good gen set, is that a pure sine wave gen set or just a really big output one?
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23rd Aug 2018, 01:37 PM #7Novice
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Hi Rusty,
I read that most cheap entry level inverter welders do not like any power source other then pure sine wave.
The more expensive ones come with generator safe ratings.
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23rd Aug 2018, 02:13 PM #8Diamond Member
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I'd expect all generators to put out a sine wave as that's the way they make power. What may vary between generators is the quality of the voltage regulation.
As for cheap inverters, the one I used is a BOC Smootharc 130, which was about $300 when I got it a decade or more ago, and is probably even cheaper these days.
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23rd Aug 2018, 02:47 PM #9Novice
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Pure sine wave is what is required to run certain electronics such as laptops etc
But many inverter welders also need Pure sine wave to work correctly and to have a long life, for example many of the cheap inverter welders on ebay are not recommended to run on generators other then Pure sine wave generators, I have asked a few sellers this question.
Higher end models will state generator compatible.
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23rd Aug 2018, 08:02 PM #10Most Valued Member
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By really good, I primarily meant big output, but quality also plays a part.
Some gensets use chopped DC, although in thinking about it, most of these have been attached to lower end mobile welders, so that negates the need to run a transformer arc welder from them, although power tools are pretty gutless when run on a chopped DC supply.
Not all inverters are created equal though and some have running issues and others short lives when run on the type of gensets that we commonly see.
The gensets we use in the field really are only designed for somewhat intermittent usage, which is fair enough. If one compares the alternator unit from a typical 8Kva unit with that found on a Kubota backup genset for example, the differences are easy to see. The backup genset alternator is almost twice the size and is run by a twin cylinder diesel, liquid cooled engine and is designed to output 8Kva continuously for long periods. Likewise, the cost of the backup genset reflects this greater performance, plus you'd need a forklift to move it.
I think the bottom line is that inverters are a vast improvement over transformer machines in just about every way, however a transformer unit can be run effectively as needs require. If I was doing a lot of site work, I'd still pick my Perkins powered Lincoln over any genset powered unit. Next would be my Lincoln Invertec 170, then finally, my WIA 12P SCR controlled transformer machine, (this machine welded an awful lot of irrigation pipes off a 5Kva Dunlite).
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23rd Aug 2018, 08:31 PM #11Diamond Member
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I should have said I was referring to non-inverter generators, which no matter how cheap, still produce a perfect sine wave. I've never used an inverter-style generator, so can't really comment on them.
It's worth noting that a laptop power supply and an inverter welder are pretty much the same thing - a switchmode power supply, although the former is designed to put out a constant voltage, while the latter is set up for constant current.
As for compatibility with inverter generators, I'm going to guess that the peak voltages and harmonics from a modified sine wave inverter are tough on the input capacitors, leading to premature failure if they're not specced high enough, and may well pose challenges for the regulation circuitry, leading to poor welding behaviour.
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23rd Aug 2018, 08:55 PM #12Novice
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23rd Aug 2018, 09:10 PM #13Novice
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