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Up Topic Welding Industry / General Welding Discussion / mobile welding off a genorator?
- - By acs welding Date 10-26-2005 20:22
i got abot 6 welders they all work real well off my genorator which is seperate unit however i just bought a miller syncrowave 180 sd
and my buddy told me i will only be able to stick weld with it up to about 130 amps and i can forget about tig welding off generator unless i use lower amps and scratch start! is this true i wont be able to use foot pedal when mobile tigging? i mig and stick off it ok the generator is 10,000 watt
13,500 surge watts also is there a batery pack i can buy to give me constant current?
Parent - - By BillC (**) Date 10-26-2005 21:38
I did some steel GTAW last weekend with my 180SD plugged into my 10kW Trailblazer. I used the foot pedal and had the current set at 120 amps DC. Worked fine for me...

Regards,
Parent - By metallord (*) Date 10-26-2005 22:01
the high freq is built in on a 180 sd.if the machine is running the h.q. is working.
Parent - - By acs welding Date 10-26-2005 22:41
i said im fine up to 130 amps ..tried it at 180 amps and generator
sounds really loaded almost bogged down to where it wanted to stall
maybe it works better with trail blazer ..i was told i cant use the 180sd at all with a generator because its solid state ? i tried it with stick worked great with the stick up tp 130 amps...havent tried tig yet dealer told me ill be fine as long as input voltage doesnt drop below 208 volt... im confused here
Parent - By OSUtigger (**) Date 10-27-2005 03:11
A 10kW generator *should* produce the same output as a wall outlet, 230 Volt, about a 40 amp breaker. I cannot see why this is not the case, but if someone does, please correct me. Yes, the engine will bog. It is sized to put out that amount of power. You engine in your vehicle does the same thing when you accelerate. As long as it's running, it can handle it, no matter the sound the engine is making. Generators are also designed to put out a constant voltage, and I will bet that if that voltage drops too much it will simply kick a breaker or reset button on the generator itself. You do not need a constant current source (if you had a constant current source, you would not need the stick welding option on the 180SD, only the TIG high freq option), nor any accessories to create a constant current source. The only reason that you could not use the TIG to its full extent would be if for some reason the welder is pulling quite a few amps to do something else other than just the welding (for example, running a pump for the water cooled torch if you have one, or perhaps a grinder or chop saw by someone else on the crew).

If this is not the case, either something is wrong with your generator or I have a completely misconstrued view of how generators actually work, and if so, again, I hope to be corrected.

Hope that helps!

gls
Parent - - By billvanderhoof (****) Date 10-27-2005 05:51
Going a bit out on the limb here, it's been a long time since that AC dircuits course. I looked at millers specs and they say at 150 amps it draws 6kw but 12.3kva. That indicates a quite reactive load and I believe your generator sees the 12.3kva as the load. The difference has to do with the fact that the voltage and amps are not in phase with each other when the load is reactive. It seems that your finding that the generator can only power it up to about 130 amps may be correct. I don't see why TIG would be different. That is works ok at lower settings. Experiment.
bill
Parent - - By acs welding Date 10-27-2005 09:36
i started my bussiuness about 4 months ago while i was still in welding school getting my aws certs when i was
shoping for genorators o had cal;led lincon electric
they told me volts x amps=watts now i added all that up and i would need 6,900watts to run it ar 160 amps in stick mode however
the lincoln invertec v 160s also only runs about 140 amp max
i was under the impression my self that it was same as wall outlet
but a couple of rhe instructors are telling me its not the same
as the wall outlet has constant power the generator doesnt so when i ask it for more through the foot pedal it won be there
sure hope they are wrong
thanks for help andy
Parent - - By OSUtigger (**) Date 10-27-2005 17:49
Andy,

Bill pinned it right on the nose. For some reason, the TIG has some sort of inductance in its circuit, and therefore it runs like a motor. You will find that if you go to an electrician and have him install a capacitor somewhere in the circuit (he should know what this means), the machine *can* work perfectly, or, depending on the skill and judgement of the electrician, about 90% efficient (this is called power factor correction, and has everything to do with the difference between kVA and watts). Sorry this didn't hit me before. You are actually pulling about 12.3 kW from the generator, but the machine is actually only using 6.9kW, therefore you have a PF of about 50%. An electric company will ask that you have the same thing done when you install a large single phase motor, because they can only charge for real power, and not for kVA.

Hope that helps.

gls
Parent - - By acs welding Date 10-28-2005 12:48
sweet..ok that was a bigg help!! as i have a real powerfull car stereo my amplifiers in the truck have capacitors which hold juice so head lights dont dimm when bass hits and i needed this even when i upgraded
stock altenator from 135amp to 220 amp any way where i was goining with this was is there a battery pack or capacitor that i could use to give me more steady power? and you just answered that for me
great guys thanks for all the help so basicly the capacitor or batt pack would go between the gen and welder?and i would get juice from batt pack or cap and gen gharges those up correct?
Parent - By BillC (**) Date 10-28-2005 15:01
No, the capacitor is not acting as a big battery pack. It is changing the phase of the AC. Do a google search on "power factor correction"...
Parent - - By OSUtigger (**) Date 10-28-2005 15:51
Again, Bill's right, you absolutely have to get the exactly right size of capacitor, and though it is storing electrons, it IS NOT a battery. It is simply realigning the sine waves. This works completely differently than how your capacitor is working for your stereo. The capacitor for your stereo is storing the electrons for an instantaneous moment when they are needed, and if you keep bumping the speakers continuously, eventually you will not be able to store the capacitance necessary to fully bump them. A capacitor in an AC cicuit more or less delays or advances voltage according to time, and makes it so that you don't have a case of peak amperage at minimum voltage or vice versa. It is hard to explain, and I don't remember everything about it like I should, but it involves real as well as "imaginary" numbers (square root of -1 stuff).

Point is, you can't just throw a big ol' capacitor in and expect it to work. You have to get the right size, and this requires quite a bit of evaluation.

gls
Parent - - By acs welding Date 10-29-2005 02:15
ok i get it im gonna have a tech do this and have it calibrated too
you and billc were a big help was getting ready to buy a bigger genorator
Parent - - By billvanderhoof (****) Date 10-29-2005 05:34
As a side benefit the power factor correction will save you fuel.
Bill
Parent - By BillC (**) Date 10-29-2005 12:39
Bill,

That brings up an interesting question... The inefficiency is current draw, but not power consumption. When you are hooked up to the local power company, you are continuously drawing more current than you need during half a cycle, then returning the excess to the grid during the second half of the cycle. What happens to that excess current with a generator?
Up Topic Welding Industry / General Welding Discussion / mobile welding off a genorator?

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