Can my tractor handle a larger PTO Generator? Confusion with HZ

[haanzel]

Researching a lot and finally ready to pull the trigger on one. One conflicting item that I keep reading is size.

It is safe to say 2 HP can handle 1KW. I have a L2500 which has 22.5HP at the PTO. Using this equation, my tractor can handle 11KW. However, Winco offers 10KW and 15KW PTO generators. I know I can safely do the 10KW but can it handle the 15KW? Some people have said that it can. But I want to ensure I stay at 60hz and not degrade the generator and/or electronics.

Does this mean that a 15KW will work fine until the 11KW load reached, and from 11KW-15KW it will/may be below 60hz? Or will it not generate 60hz at all, regardless of load?

I don't want to sell myself short and there is always the option of getting a bigger tractor down the road, but that is not on the table for now.

 

[07wingnut]

In my opinion, you would be Ok up to the 10 kw, and maybe a little more, since your twofer ratio isn't exact. There should be little problem with the larger generator until you exceed the tractor power limitations, so good load management is a must. On our farm, we ran a 45kw with a 70hp tractor with no problem, and when the large loads were no longer needed (ie, unloaders, gutter cleaners, etc) the pto was put on the 1000rpm pto shaft, and the tractor run at half speed. That would probably be 30hp running a 45kw generator.
If you are not wedded to the idea of a pto generator, and you only have one tractor, you might consider a stand alone generator. The price difference might not be as large as you imagine. Frequently the conditions that cause power outages result in scenarios where a tractor would be really handy.

 

[GeoHorn]

I cannot help but think it would be a good idea to back off to arms-length and re-assess the physics and economy of a PTO-generator.
A PTO generator is considerably UN-economical, not only as for original expenditure for the complete set-up... but also for the economy of operations. To use a 20+HP tractor to drive a 10K generator.... which can be handled by a portable generator with a 5-8 HP engine consuming considerably less fuel and costing much less on a kilowatt-hour basis.... does not make sense for most applications. The wear-and-tear on a tractor....which cannot be used for other purposes while acting as a stationary producer of electricity .... costs many times more per kilowatt than a portable or even most stationary generators.
If you have a Tier 4 tractor... you may have regen issues that may interfere with your electric-production at inconvenient times.... but the cost-per-hour of using a (relatively speaking) large tractor diesel to run a small (10-15K) generator is an out-of-balance expenditure of economy.
IMO

 

[William1]

The issue with running a PTO generator is matching throttle setting to load too. You fire up the tractor, set it to the appropriate rpm. Add load, the rpms drop so you have to increase the throttle slightly. Add more load, more throttle. Drop load, drop throttle. a real PITA. A genset has a throttle control that self adjusts as the load varies. If you are using the generator for a steady load, no big deal. You set the rpm slightly high, add the load, fine adjust the tractor rpm. Away you go. But if the load changes....
The larger the tractor and the larger the generator, the less of an effect a slight load change will have.
I have a 22.5Kw genset on my house. As the load changes, I can hear the genset adjusting to suit. Lights do vary ever so slightly in intensity. Most electronics are on UPS to clean and smooth the power.

 

[85Hokie]

Geo and Will said it better than I have said in the past!

The pto genny is a neat trick - but for the bang of the o mighty buck - not very economical al all!

 

[William1]

I admit, I like the 'idea' of a PTO generator. One less engine to maintain. However, if it is for emergency power, you have to fire up the tractor, get the generator out of where it is buried as you so rarely use it, get it on the 3pt. then feed the house. I'd thought about it pretty hard. But then when I considered the loading/throttle issue and hook up then when I did hard core shopping. it just did not fly. I got a 'portable' 22.5Kw gas powered Generac for $2K delivered ten years back. My wife can/could roll it out of the corner of the garage if she had to. No way could she put a generator on the 3pt. (even more so as my little guy always has the BH on).
I wish I had a massive propane tank or natural gas, and had a permanent whole house genset. Ot better, a big commercial diesel unit and a 500 gallon tank of diesel along with a massive inverter and battery pack. But, I get an outage once a year, at most it is 36 hours (except for Katrina) and usually it is just a couple of hours. I am also not rich.

 

[ThomasH]

The AC frequency (Hz)is strictly a function of RPM on a synchronous generator (not to be confused with an inverter generators). The target frequency is 60 Hz. As the load increases on the generator, it takes more power to maintain that RPM. The challenge is that the tractor's throttle and governor are not designed to maintain exact RPMs under load and variations of load. Some deviation of frequency is acceptable, but I can't remember the amount. I do know that home appliances are becoming more and more picky about clean power (voltage and frequency). And too much deviation of either can fry appliances. This is especially true of newer furnaces and refrigerators that have sensitive IC boards.

 

[thirdroc17]

The answer to the actual question is, you can run as big a generator as you want and not harm the tractor. However, you'll only be able to generate as much electricity as the available power can create. Meaning, you will not get more than your stated 11kw, regardless of generator capacity.

 

[Popgadget]

As long as your PTO turns the driveline at 540 RPM, the generator will work correctly. There is no need to work the throttle, other than to set it for the proper PTO speed. The tractor’s governor will keep it on speed until the load exceeds the available power. You are correct that 2hp per kw is a good rule of thumb, so with that in mind it’s unlikely that you will be able to get all 15kw, but it will work fine up to the point where you run out of power.

 

[random]

Frequently the conditions that cause power outages result in scenarios where a tractor would be really handy.

In my limited experience, that's almost always the case, at least in my area.