PTO Driven Generator

You said you need a minimum of about 30 amps, Roy. Okay, that's a 3500 watt generator. The general run of reasonably-priced PTO-driven generators is about 15KW - about 4 time your 3500 watt minimum. That's a healthy margin of excess. Maybe too healthy; it takes roughly a gallon of diesel fuel per hour to run a 8-10KW generator. There are some economies of scale, so a 15KW takes only about 1.25gph - if the engine is sized exactly to the load. That's where the stumbling block comes in on tractor-driven generators. You're going to be running a 40hp engine to power a generator that really only needs about 22hp to push it. Overkill. You don't get the option of loafing the engine along in a higher gear since we're talking about a diesel that uses a governor and a fixed PTO speed - you have to run it at the proper speed to develop the proper voltage.

A 15KW PTO-driven genset will cost anywhere from $1200 to $2000 depending on where you get it. A smaller, dedicated generator would cost about the same if you get a diesel unit. Perhaps a bit more if you opt for water-cooled diesel. But the fuel savings and the freedom of having the tractor unencumbered might well be worth it.

Small diesel gensets usually are 3600 rpm air-cooled units - not the ideal setup for long life. A better solution is a genset with a water-cooled diesel pushing a 4-pole alternator at only 1800 rpm. Much longer service life, quieter, and better fuel economy. But, a higher front-end cost. There's no such thing as a free lunch, right?

It probably boils down to how much run-time you're expecting from the genset. If you plan to run it for long periods on a regular basis, then I'd say definitely get the water-cooled, low rpm diesel dedicated genset and build a house for it. If you only plan on using it for a hour or three per day, or less than that, stick with a cheap gasoline unit and figure on replacing it every couple years. Or even a cheap air-cooled diesel.

Well, that sums up what little I know about generators, having lived with them continuously for the past twenty years. My need is for an economical generator that will run the whole house when the local utility is out of commission after a hurricane or some such, so I have a 10KW gas generator. The thing is too noisy, too much maintenance and expensive to run but it is still the best bang for the buck since I don't use it regularly. A diesel needs to be "exercised" every two weeks or it will die too soon. Something else to consider.

Hope this helps rather than just confuses the issue.

There's no contest as far as I'm concerned, between the ST generator head and the HF unit. Hands down, the ST generator will outperform and outlive the HF - by a factor of say, 10 to 1. The ST generator heads are the preferred unit for the guys who build somewhat permanent gensets for off-grid living, usually powered by a low-rpm diesel, a Lister-Petter if they can get their hands on one. The L-P runs at about 600 rpm so they last forever with moderate maintenance.

When I get the property cleared and a house built I'll be looking into one of the 15KW ST generators and suitable small diesel engine to power it. Probably a Chinese diesel tractor engine since I have some familiarity with them now. ;D

If you can get utility power at any halfway reasonable installed cost that would be the way to go, Roy. You simply cannot generate your own power as cheaply as the utility can. Down here, where our electricity is outrageously expensive, it is still cheaper than generating your own unless you're up to half a megawatt or more. Even so, our monthly "paperwork" fee is only about $6.50 if you use no electricity at all - it would take years and years of $6.50/month to equal the cost of even that cheapo diesel you're looking at.

BTW, those air-cooled 3600rpm diesel engines don't have all that great a life expectancy. Only about half again what an equivalent-sized gas engine would have - say, maybe 500-1000 hours. A water-cooled diesel running at half that rpm should have a life expectancy of 10,000+ hours with decent maintenance. One of the big issues with small generators, either gas or air-cooled diesel, is that they run the generator head direct-drive off the crankshaft and expect the crank bearing to also be the shaft bearing for the generator. Definitely a prescription for premature failure. Better units use either a Lovejoy coupling or secondary drive and the generator has its own bearings.

Here is what I have at this point. Basic service charge $17.50. That was great, but installation a is a different matter. Wire was close to $8.50 a foot. I would guess I am looking at about 800 ft plus. Now over head on poles, it is up to me to clear a 20 foot wide path across my property & the neighbor for easement. That would take a bulldozer, more $$. Under ground I would have to trench & install 2 1/2 inch pipe with a string. 30 inch minimum depth. With the boulders that we have encountered with just the driveway & pole barn I don't see that being a good idea either. Called the neighbor to see if it would be OK to trench across 40 foot of his easement but he has not called back. When the wife & I go their we don't use a lot of electric but if I want to run the air I would have to have power. I was looking into a combination generator/welder.

cgi.ebay.com/6000Watt-Diesel-Generator-Welder-10HP-OHV-Engine-3548-/310307621788?pt=BI_Welders&hash=item483fc68b9c

Something like this & add a remote start. Any more thoughts??

I did read your epilog with the capacitor earlier. Very good. Are you still happy with what you have now? I have a cheap gas 4000 watt gen that I bought a few years ago at one of those tool sales at the Legion Hall in Hobart Indiana. Any how the 4000 watt gas unit will run every thing I have asked of it. Camper has a 120 volt 30 amp plug on it so that is why I was looking for 120V@30 amps. Still thinking but not sold on the idea as of yet.

Have you gone to Synthetic Oil?

Roy

PS - I had a friend drop off these the other day along with hardware. I hope they fit.

Thanks for the input. I am a big fan of synthetic oils.

Roy