Generator sizing

[Bevel]

I have a miller matic 211 welder and am moving into an off grid situation. Does anybody have any suggestions on a good generator to power the welder. I believe I need a minimum of 10000 watts, and would like to be somewhat portable I've looked at many brands. The aurora 10000 watt stands out any suggestions.

 

[Willie B]

A 10 KW generator should offer 41.6 amp continuous. I don't have a 211. The primary amperage is printed on the nameplate. I have powered my miller 252 MIG machine with a 40 amp primary with a Kohler 7000 watt machine. It is uncommon to load a welder to full load. When buying a generator for off grid, you need to think of fuel consumption. I have used Outback Power Systems equipment for a storage bank. we powered it with a 3000 watt Honda generator. In truth the Honda was built for less duration.
I just bought through Craigs List a Miller Bobcat welder. These are wery heavy duty machines. New, they are somewhat expensive, but worth the price. For MIG or TIG you need a plug in welder or a suitcase add on accessory. These machines are built for the long haul! They are built for professional welders to use every day. With regular service they last for years. They are backed by excellent parts and service. I consider a fixed machine a poor choice for off grid. When it breaks, a mechanic has to come to you. A heavy portable machine can be loaded on your vehicle and taken to service.

 

[joshuabardwell]

Sizing a generator to run a welder is tricky because welders have huge inrush current. The welder may be rated to draw 30 amps (for example) at max output, but for a fraction of a second when you strike an arc, it may draw 100 amps (for example). On household current, this is no problem, but a generator will bog down. When that happens, the voltage drops and you lose your arc. The exact specifics depend on too many factors to account for in a forum post, but the bottom line is that you should test out your welder on a generator before buying. Be sure to measure voltage on the line while welding, to be sure that you're not running in an under-voltage situation. In many cases, it becomes more cost-effective to buy a motor-driven welder and use it as a generator, than to buy a big enough generator to run your mains-powered welder.

BTW, I have a personal theory, that I have yet to test out, that if you are doing pedal-controlled TIG, or 4T TIG, that this problem goes away, because you can strike the arc at a very low amperage and then slowly ramp up in a controlled manner that won't exceed the generator's abilities. But stick and MIG are another story.

 

[buickanddeere]

All depends but don't figure that 9050W of load can be handled continuous with a 10,000W generator. The capacity on a small generator in particular is on the ragged edge of failure if used continuous . In particular in hot weather.
Wonder if a battery bank, an inverter , 1000-5000W of solar panel which are now dirt cheap. A 2KW wind turbine. Should be able to get by with minimal generator use.
If building a house from scratch now in the country. Probably would not even connect to the grid unless it was to sell power or to net meter.

 

[Willie B]

Another factor is that plug in inverter machines IE MIG or TIG are dramatically lower in their energy usage than older transformer machines. My "Twentieth Century" AC-DC C.1974 is still a great welder. In function, it can compete with state of the art new machines. It can't, however compete with energy efficiency of inverters. Energy entering a machine "can neither be created or destroyed". It can be wasted. All welders are highly refined heaters.The work we want it to do is heat metal to the melting point. Other heat produced is waste. An inverter places more of its percentage of heat on the weld, less into the upper atmosphere.

My 252 MIG at 40 amp peak primary will complete more in a minute than my 20th century. The new MIG stays at acceptable voltage on an underrated 30 amp generator. The older transformer machine would stall or smoke the generator. Its 60 amp primary is severely underrated, more of an average, stick a rod, look at an ammeter. NAEC allows us to overfuse a welder circuit by a factor of 300% for a reason.

Welder manufacturers usually double the horsepower that calculations call for. Slow the engine by sticking a rod, sets in motion a chain reaction that ultimately ends in either a stalled engine, or a failed generator circuit.