15-20k watt PTO emergency generator recommendations?

[Fallon]

I'm looking to pull the trigger on a PTO generator here in the next few months.

Kubota L3200, 25 PTO HP, which translates into 18k watts. I may end up with a beefier tractor later. Generally I'd rather get a little bit to big of a generator than to small of one. It's easy to run a big generator with a lesser load than the other way around & if the load on a bigger generator is more HP than I have I just stall rather than breaking something. I'm not sure of our peak or average power draw, but am confident I can manually manage things as needed. It's trivial to shut off the hot water heater or the A/C we have yet to install.

I'll be getting a manual transfer switch & this is for emergency use, not really standby use. It gets cold here in Colorado, so I want to make sure I can heat the place, but am not that worried about an hour or 2 of power outage. We haven't had anything over an hour or 2 so far in the year and a half I've lived at our current place. There is a good chance I'd use it for some other stuff away from power from time to time as well, but not often.

15k watts = 62.5@ at 240, so a single 50@ 240v might be pushing things if I'm trying to run the whole shebang through 1 socket. That does seem to be what most of the generators I've seen.

Harbor Freight has a 16000 Peak/15000 Running Watts Tractor-Driven PTO Generator for $1.5k (before I dig up a 20% off coupon). That includes a frame & PTO shaft.

Northern Tool has NorthStar PTO Generator 13,000 Watt, 24 HP Required for about $1.5k with no PTO shaft or mounting frame.

RuralKing has 24,000KW Rural King PTO Generator for $1.5k & a 50KW for $2.3k that has a 63@ plug. Not clear if those are single phase or 3 phase though, looks like it might be able to do both. 3 phase would be handy for a rotary converter if I ever end up with a big lathe or mill out in my shop that runs on 3 phase, as long as it could pump out single phase for the house.

Any recommendations on these, or any others that are rated a bit higher? I've been keeping an eye on CraigsList, but haven't seen much show up in quite some time.

 

[buickanddeere]

Go with a large single phase. It's not a good idea to operate a commercial generator at or near 100% load . As for the three phase motor, a variable frequency drive to make three phase from single phase beats any rotary converter .

 

[bcp]

Harbor Freight has a 16000 Peak/15000 Running Watts Tractor-Driven PTO Generator for $1.5k (before I dig up a 20% off coupon). That includes a frame & PTO shaft.

Some, if not all, of the HF coupons of which I've read the fine print, exempted generators.

Bruce

 

[shawnspeed]

Just a word of caution on buying too large a genset for a pto...it will severely lug the tractor and give you an under voltage situation that will possibly cost you some cash with burned up stuff like refrigerators, freezers, sump pumps ect...I would buy a little smaller and have some extra HP for the serge loads. A good friend of mine has a dairy farm and has several PTO gen sets...one is a 75 or 100 KW ...it makes his MF 1155 bark( 150 pto hp) when the coolers & vacuum pump in the milking parlor both are on..last year during the ice storm he went thru 3500 bucks in diesel for the week...they do load the tractor...even with light loads...just some food for thought...Shawn

 

[s219]

I don't think you can take the rated PTO HP and assume you can produce an equivalent amount of electrical energy in kW. There will be losses in the mechanical to electrical conversion, so the electrical output will be less.

When shopping for my diesel generator (eventually got one with Isuzu 4CYL 4LE1 engine) I was seeing 3-6 kW of disparity between the diesel engine's power at 1800rpm and the output electrical power from the generator head, for units in the 20-25kW range. Some of that is due to losses, some surely comes from running the engines at less than 100% load to provide some reserve and factor of safety. So anyway, don't plan to get all of the 18kW from a 25HP PTO based on a straight HP to kW conversion. I think for a 25HP PTO, assuming the generator is geared so that you are running the tractor at the rated RPM to achieve that 25HP at the PTO shaft, plan on more like 12-15kW of reliable electrical power.

I'd suggest being conservative with the generator requirements so that the tractor engine can maintain output and the generator can maintain voltage. Electrical generation has a fairly narrow margin when running appliances, electronics, etc.

I don't know the implications of hooking up a large generator head to a lower-rated engine, but knowing the engine will be running at constant RPM and power delivery will vary based on loading and balanced by fuel input, I can see how a large capacity generator head (like the 24kW and 50kW Rural King models you cited) could really lug down a 24HP engine. Even if you don't plan to load the generator to the full amount, the potential is there to really beat on the engine.

 

[aczlan]

There are a couple of people on here who have way oversized gensets on their machines (30kw on 18HP?). IIRC, they use a breaker sized to the tractor output to limit current draw to what the tractor engine can handle.
So, if the engine can handle 30 amps, it gets a 30 amp breaker even if the genset came equipped with a 100 amp breaker.
A larger genset will take a little more power to keep spinning, but it will also handle larger surge loads.

Aaron Z

 

[zzvyb6]

I frequently use a 50kW Winpower PTO unit behind my 35 hp JD. Never had a problem. Often used it behind my 22 hp Yanmar. Bought it at a Farm auction for about $1000 as I recall. Came with all the switch gear and cables. Often use it for non-emergency applications, too. That includes welding, tree spraying with my electric power washer, and even a hedge trimmer. I can even use it on my diesel lawnmower. So, its a contraption in someone's illiterate words. So what. I have power and they need a shower and a flush.

Never had to consider using the tractor for 'other things' when the power is out. You don't need electricity 24/7. Just when you want to pump up the well pressure tank, heat or cool the house and to surf the net for the power outage map.

 

[Fallon]

I appreciate the conversion losses & what not. For now its just our well, propane furnace, 2 fridges & a freezer along with lights. I'm confident we can manage the load to the lowest common denominator. We wouldn't be running it 24/7, just enough to keep the house warm, watered & the food cold.

I'm sure I can see how well my governor & the other components work giving it a calibrated workout with my welder. Can add enough load that wont wig out when I reach the limit & see what it is.

Making sure that weak link is a breaker rather than lugging the engine sounds like a great idea.

Still looking for advise on what the best or at least most economical option is for a new generator is. Still hoping for a Craigslist or auction find for cheap, but no luck in quite some time so far.

 

[newbury]

<snip>and to surf the net for the power outage map.

AND TO GET ON TBN!!

<snip>
Still looking for advise on what the best or at least most economical option is for a new generator is. Still hoping for a Craigslist or auction find for cheap, but no luck in quite some time so far.

Go to Harbor Freight TODAY and get their little 1K gennie for $90 (Black Friday special, online also). Swap out the sparkplug. Break it in and baby it. You've now got enough for a few lights etc.

And constantly search CL, auctions etc. if you are seriously trying to save $$$.

I was in a similar situation, badly wanting a PTO generator, and after about a year of searching my local area found one, an almost new Winco 12KW, for $600 w/ PTO shaft and pallets it's mounted on. Over the years I've seen several more, usually larger, but they are rare and often heavily used. And set aside $100/month for a good name brand one. A generator is not something I'd cut corners on if I'm spending a decent amount.

 

[s219]

There are a couple of people on here who have way oversized gensets on their machines (30kw on 18HP?). IIRC, they use a breaker sized to the tractor output to limit current draw to what the tractor engine can handle.
So, if the engine can handle 30 amps, it gets a 30 amp breaker even if the genset came equipped with a 100 amp breaker.
A larger genset will take a little more power to keep spinning, but it will also handle larger surge loads.

That is a great idea -- simple and effective way to limit things safely.