Need recommendation on size of engline/gen set needed to power a shop

[krazion]

Hi,
I have 4 friends who have listers for emergency power.  I am looking to use a Lister as my primary source of power.  I need a recommendation on the size needed to power my shop.

I will be running 230 volt single phase compressor, mig welder and plasma cutter.  In my office space I will have a small window unit AC and a hot water heater (on demand H2o)  water well pump, and shop lighting, misc power tools.

I have looked a various sites offering listers of sizes ranging from 14 hp/10kw gen  to 24hp/15 kw gen.  What I can't find out is what is the right size to match my power consumtion needs.

Any ideas?  best brands?  vendors?  etc?

I reside in AR.  I am looking to start immediatly so I can have my lister ready and working prior to winter months.

[Jim Mc]

Way too open-ended of a question. 

You might want to provide a few more details, such as the HP and full load amps for the compressor, the MIG welder primary current, size of A/C unit, current requirement for plasma cutter, amount and type of shop lighting, other big motors, and the current requirement for the water heater. 

Also, what is your expectation about using more than one load at a time - needing to operate all this stuff at once is gonna drive you to a much larger set than if you're willing to manage loads.

At an even higher level, why, on God's green earth, do you want to use a Lister (Listeroid?) as PRIMARY power?  No utilities available? (OK, maybe it makes sense)  You think it'll save money over utility power? (Do the math!!)  Or maybe you just like the smell of Diesel. (Me too, can't argue with that!)





 

[mobile_bob]

I'm with Jim on this one, need more details, remember the devil is in the details.

you are likely going to have to run upwards of a 25/2 or a 28/2 with a 15 kwatt head, and even then i don't think  you can run all at once.

with some load shedding components (controllers) you can probably get the job done, if you are a one man shop.
as am example:

a controller (relay with timer) can kick off the air conditioner when you fire up the welder, but bear in mind it will have to have a time delay to enable the head pressure to nomalize on the a/c compressor or it will try and restart against pressure and shorten the motor life.

all of this can be automated, or done by hand if you have the time and inclination or lack of funds to automate the process.

unless your fuel is free or nearly so, you likely won't save money over the grid unless you harvest and have use for the rejected heat.
in the winter i am sure you can use all the excess heat, but summer is another matter.

not sure what your welder pulls at max welding but mine is on a 50 amp breaker and does trip it at high settings, so it needs in excess of 12kwatt to operate at high amperage, this leaves not much for other loads,

if you were welding at max and the air comp tried to start you may overload even a 28/2 with a 15kwatt head should you have a fair size compressor and it kicks on while you are welding.

this is a tall order for a shop i would think unless you plan well, and schedule your loads or shed them as needed.

bob g

[mobile_bob]

a better approach might be the use of two listers ( i think Hotater does it this way)
one that is sized appropriately to handle the a/c unit and office equipment, lighting etc.
and another sized to handle the heavy lifting such as the welder, plasma cutter and air compressor.

it would appear to me that sizing a lister/gen to handle the max loading would leave it loping along at very low load most of the time.
the engine probably would not build enough heat to become as efficient as it might otherwise be if it were loaded up to about 80%.

it would seem like maybe a 6/1 or better yet a 8/1 with a 5 kwatt head would be a pretty good match for running lights, airconditioner, and office loads, a bench grinder, drill press or so and do so at near rated capacity and thus peak efficiency.

a 25/2 or 28/2  with a 15 kwatt head would be able to handle the heavy lifting, unless you try to run the welder, plasma and the aircompressor kicks on all at the same time. with some thought this would work pretty well and have the engine up to reasonable efficiency.

there is alot to consider

bob g

[krazion]

I appreciate the info I will be using biodiesel in the engine which I have access to large quantities of oil for free.

 Today I put pencil to paper and estimate average consumption 6.2kw to 7.5 kw.. My machine useage is a single worker and myself working on aircraft projects.

When we are both working I estimate loads @10.7 to 11.8kw appx.

Do you guys think a 24/2 w/15kw a good match?

I want a Lister just as a living history project and to experiment for a remote home .off grid incorporating solar / LED lighting /and a Lister.

THX
Krazion

 

[diesel guy]

Krazion,

With the information you provided (more is needed). But for what its worth, I would purchase a 28/2 with a ST 24 KW generator head. Then purchase a dual sized pulley system to drive the generator.

The first pulley would provide 60 cycles at 800 RPM and produce 12 KW continuous and 14 KW for short term. Which offers 2 times generator size vs. load, for high surge requirements.

The other pulley size would provide 60 cycles at 1,000 RPM and produce 15 KW continuous and 17.5 KW for short term. Which offers 1.6 times generator size vs. load, for high surge requirements.

The first one would enable better fuel economy and lower noise and the latter would provide higher output incase there was a need for more power, at the expense of higher fuel consumption and higher noise level.

This setup is like having 2 generators with one setup, just change the belt and engine speed. Always remember an oversized generator head consumes “slightly” more fuel per given load, but can provide higher peak surge power when needed. If equipped with a properly sized generator head (15KW) it could fall flat under high surge conditions and cause premature electric motor failure.

Diesel Guy

[hotater]

Krazion---

I live way off grid on generator power only, except a small inverter on batteries for middle of the night internet access if needed.

My shop is a one man, mostly three phase, machine shop with a 220 amp TIG welder (usually run at 120 or less), 5HP bandsaw, 5HP lathe, 3HP mill, 2HP surface grinder and all the lights, hand tools and drill press, sharpeners, etc needed to make or repair what interest me.  I run the entire shop, including 400 watts of florescent shop lights on an Onan 15Kw water cooled diesel.  I run the welder fan and a couple 1500 watt electric space heaters (outside in summer) to load the generator some.  Otherwise it carbons up and gets smoky in a hundred hours or so.  On days I don't need the bandsaw and do need water I run it's power source (everything on waterproof industrial plugs) to the 3HP well pump which draws enough to keep the Onan running clean.
   Unless you're an "in the shop and working eight hours straight" guy, running a shop by genset is a true pain in the rear.   I hate the roar of the Onan but it's nice to have compressed air all the time or be able to run a grinder/wire wheel 'just for a minute'.

My Lister runs all the main building's needs about 15 hours a day.  I have it wired 220 that's then split into two circuits with four wall plugs each.  The freezer and 400 watts of lights and the building heat pumps in winter takes one circuit and the computer room (300 watts) and 800 watts of lights and wall wart battery chargers take up the other.

You can run what you have now on 14 to 15 Kw, but that means that great doodad for $19 at the auction but is three phase means a new generator before it's useable.....and it WILL be!  
Think of generators just like machine tools.  You can do small jobs with big machines, but you can't do the big jobs with a small one.  

I'm in the process of re-designing a house and shop.  I'll use at least two generators.  One large and one small.  There will also be a spare and a 4Kw portable gas just to pre-heat engines in the winter, too.

If you're off the grid your power needs change a LOT.  Think hard on it before committing to one plan.

My story is posted at   http://www.utterpower.com/jack_belk.htm