keithjh Posted August 6, 2009 Share Posted August 6, 2009 Hi All, Need a grown up to help me with this not enough fingers to count on Basically what size genny will i need to run a 200 amp Mig comfortably, Regards Keith Quote Link to comment Share on other sites More sharing options...
ejparrott Posted August 6, 2009 Share Posted August 6, 2009 Amps = power/voltage so 200=power/240 (presuambly, not three phase is it?) so 200 x 240=power =48,000 watts, or 48Kw theres a catch though, whats the input power, not the welding power? Quote Link to comment Share on other sites More sharing options...
keithjh Posted August 6, 2009 Author Share Posted August 6, 2009 Amps = power/voltageso 200=power/240 (presuambly, not three phase is it?) so 200 x 240=power =48,000 watts, or 48Kw theres a catch though, whats the input power, not the welding power? Oh god now i`m even more confused , yes its 240v and its err a Mig Keith Quote Link to comment Share on other sites More sharing options...
ejparrott Posted August 6, 2009 Share Posted August 6, 2009 what plugs fitted? 16A blue round? Quote Link to comment Share on other sites More sharing options...
custom-conversions Posted August 6, 2009 Share Posted August 6, 2009 Oh god now i`m even more confused , yes its 240v and its err a Mig Keith Most 200 amp mig welder will be around 13-16amp on 230v I reckon. They have their 200amp rated output at a lower voltage. So I don't think you'll need a 48kW generator or anything close to that size. That size of generator would cost you thousands! Quote Link to comment Share on other sites More sharing options...
santalars Posted August 6, 2009 Share Posted August 6, 2009 That's no so easy. The welder weld with 200 amps, but not on 240 volts. There is a transformer built in. There is a specification on the welder saying how much amps it draws at 240 volts. Ususally it will not be more than 16 amps. That means then 3.8 kW Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 6, 2009 Share Posted August 6, 2009 This has been covered several times. If it draws 16A (ish) then you need a generator that can happily kick out a lot more power (usually 2x) as the initial surge current is quite large and can bog the motor down or trip the breakers if it's marginal. So, if it uses just under 4kW you really want a 6-8kW generator, bigger is better. Of course, if you only need to run your 200A welder at ~10% power when it's on the genny, then you can scale that down (although probably not by 90%). Quote Link to comment Share on other sites More sharing options...
GL88 Posted August 6, 2009 Share Posted August 6, 2009 I was told that anything over 13A on mains has to be permanently wired to a dedicated supply. And when I bought my MIG that I was told that a 150A welder was marginal for 13A and bigger would certainly need permanent wiring. What are you planning to weld with your 200 Amp set and is there any chance that you'll ever use it on thicker steel? Google will tell you (and I haven't looked) but I'd have thought that on a Land Rover you'd never get close to maximum currrent without blowing holes in it. My 135Amp welder will happily weld lap joints all day in 3mm steel and I've never had it on full power so I'd anticipate it was fine up to 5mm for shorter periods. But if you may need it for more then you need a bigger generator and a suitable means of connecting it to the welder. If you use your welder on full power then you will find that much (but not all) of the kit on sale overheats and trips out if you use it constantly. So they sell stuff that you can use constantly on mid capacity or at full chat for short periods. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted August 6, 2009 Share Posted August 6, 2009 Yes a 200A welder will need a dedicated supply (i.e won't work at full blast off a domestic 13A 3 pin plug - though it probably will at lower power settings) No it won't need a 48KW generator so that will save you about £15k for starters I think our welder over in the workshop is a 200A arc and I think it runs off a 240V 20A spur with dedicated 32A blue plugs (bigger version of the 16A generator type plug), 20A is 4.8KW. When we first got it, we used it from a 3 pin plug but it would pop the fuse at much over about half power I think, and the plug used to get a bit warm too so we had two dedicated sockets installed in the workshop to feed it and now it's fine. As Fridge said you want some reserve capacity on the generator as a welder is a horrible, lumpy up and down load for a generator and it will poo itself if it is running close to max capacity. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted August 6, 2009 Share Posted August 6, 2009 Here's an example with specs listed:- http://www.r-techwelding.co.uk/welding_equipment/Mig_Welder 200A mig (second one down) has power requirement 19 amps at 240 volts which would be a little over 4.5KW. I wouldn't try running it with anything less than about a 7KW generator - something like a Lister TS2 would be a good place to start I would think. 10KW would be even better. Quote Link to comment Share on other sites More sharing options...
keithjh Posted August 6, 2009 Author Share Posted August 6, 2009 See i was right adults came along and answered the question, though i did think the figure of 48Kw was a bit over the top.... But i use it in the workshop on a dedicated 16 amp supply and its fine. Anyway i have been looking at a 7KW generator so i may get that one or keep looking for something a bit bigger. Thanks a lot to all who answered Keith Quote Link to comment Share on other sites More sharing options...
ChrisM_110 Posted August 6, 2009 Share Posted August 6, 2009 Witham the MOD disposal peeps used to do Oman spec gennies in Sankey trailers IIRC. May be a nice cheap option. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 7, 2009 Share Posted August 7, 2009 Witham the MOD disposal peeps used to do Oman spec gennies in Sankey trailers IIRC. May be a nice cheap option. You also find static gensets on eBay sometimes, although I have found myself straying off and looking at towable plant sets and stuff like lighting towers. IIRC you can get ones which are a generator & compressor for site work, could be handy. Quote Link to comment Share on other sites More sharing options...
errol209 Posted August 7, 2009 Share Posted August 7, 2009 200 amps at mains voltage = typical power consumption of three residential houses, and about the peak output of a 2.5TD (I worked this out to see what I might do with a surplus TD engine, but the fuel consumption for an hours' running isn't clever ) Quote Link to comment Share on other sites More sharing options...
ejparrott Posted August 8, 2009 Share Posted August 8, 2009 Amps = power/voltageso 200=power/240 (presuambly, not three phase is it?) so 200 x 240=power =48,000 watts, or 48Kw theres a catch though, whats the input power, not the welding power? Like i said, thats not the input power. I have never heard of any requirement for a welder being permanently being wired in after a certain power rating. Mine at home runs on a 16A round blue plug, our diddy one at work runs on a standard 13A plug, and the Fab shop up the road are all plugged in when required anyway - i know this because they bring them down to us to do in-situ welding....and because i spend too much time up there... Welders have confused people for many years, because they are rated in their welding powers and not the power they drawn from the grid. When i havent worked it out for a while, i always use a kettle to remind myself of the formula. The biggest kettle you can have is 3Kw or 3000, and it runs on 240v, on a normal plug, and it works out at 12.5A. Somewhere on your welder or in the manual, will be a rating plate for it. This will tell you the input voltage and current or power, and will tell you the welding voltage and current. You'll most like find the welding voltage around the 50V mark, and the current we already know to be 200A, Im guessing from my own that your input will be 240V and 16A As has been said, look for a genny that can output twice that! If you're drawing 16A at 240V, thats 3.8KVa, and is 3.8KW, I'd recommend a 5 or 6 KVa genny myself, just had a look on fleabay for you and theres quite a few around the £300 mark. Hope This Helps Ed Quote Link to comment Share on other sites More sharing options...
ajh Posted August 9, 2009 Share Posted August 9, 2009 Or get a zena mbile welder that does 200A and fits where the aircon would go or with a piggyback bracket. Quote Link to comment Share on other sites More sharing options...
martinspragg Posted August 9, 2009 Share Posted August 9, 2009 On the back of the welder there will be a plate giving the spec of the machine. So if it says 240v 16a input and factoring in the 2x for the start up spike you would need 2x240x16=7680 kva (or watts). In the genny specs there will be a continous output rating and a max short term rating. To be safe you should try to get a genny that can supply continously what your spike power consumption is. Welders consume 240v but the actual weld tip is probably only at about 12v (I can't remember what it is and it's too late to look it up) so 200amps at say 12 volts is 200*12= 2400 kva. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted August 9, 2009 Share Posted August 9, 2009 just looked it up, mines 18 - 28V welding voltage Quote Link to comment Share on other sites More sharing options...
santalars Posted August 11, 2009 Share Posted August 11, 2009 If the welder should be for mobile use only it might be of more benefit to get a welding generator. This will produce lower current and higher amps and will work more effectively as ther are less transformation losses. In one of the mags was recently an article from a guy (professional welder) who had a welding generator installed in his Defender (250 Amps i think) instead of the standard alternator. Edit: Sorry probably not a suggestion for mig welding-----so forget it. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 11, 2009 Share Posted August 11, 2009 This will produce lower current and higher amps Do you mean lower voltage and higher amps? A welding generator may be a good bet, they crop up on eBay but as you say, they're usually arc type. You may be able to use a spool gun such as a readywelder to convert them to MIG operation. Quote Link to comment Share on other sites More sharing options...
hattymender Posted August 11, 2009 Share Posted August 11, 2009 Keith, you've got a nice, warm garage that I'm totally envious of. Why do you want to go fooling about welding outside? Quote Link to comment Share on other sites More sharing options...
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