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3 Pt PTO generators
I have read all of these posts, but i have not actually read anything to sway me one way or the other. I am considering puchasing a pto driven generator for some of the same reasons i have read here. Only 1 motor to service and maintain, but i want the extra power so that i can power my heat pump, water heater and stove. Who makes a really good economical pto generator?
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3 Pt PTO generators
Bobby,
You'd better have tractor with lots of HP if you want to run that kind of stuff off of a generator. It takes roughly 2 PTO horsepower for every KW of generator. I don't know but it would probably take a 20KW (if not more) generator just to get the heat pump going. At that you need a 40 HP PTO tractor. Most people use generators just to get by until the juice comes back on.
Billy
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3 Pt PTO generators
Generally speaking, economical and pto do not co-exist in the same sentence.
You can easily buy a very good and powerful generator with its own motor for half the price of a three point pto generator only outfit.
If that isn't bad enough, and here is the thing that threw me off the scent; how do you regulate the power?
A stand alone generator has a feed-back loop to the engine that will speed it up as demand increases and throttle back when it subsides. How do you get your tractor to do that? Near as I can tell you either over produce watts or suffer brown outs that send you running outside to kick the throttle up a notch.
Too many problems and too much expense for me. I have come to the same conclusion as my friend Billy. Buy enough generator (free standing) to eek by till the power comes on again.
Since I am in the midst of a remodel anyway, I may just run a separate set of wires/outlets to the refer, freezer, wood stove fan and a couple outlets for lamps. Then all I gotta do is drag the propane camp stove in the house so I can have some breakfast.
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3 Pt PTO generators
Early Christmas morning and nothing to do yet except talk about generators. Hope everybody has an enjoyable day.
Here goes. It's sort of like hydraulics. The output from an AC generator mostly depends on the load rather than the generator. Engine RPM mostly affects the frequency of an AC rather than the power capability. When the load increases, more HP is required and the tractor governor increases throttle in an attempt to maintain RPM.
The tractor's governor handles load changes but it does have to be good and also matched to the generator. The max generator load before the main breakers pop should not be capable of lugging the engine. 1 hp ='s about 750 watts. The 2 hp/1kw rule has to do with efficiency, duty-cycle, start up load surges etc.
Where RPM and load do come together is that the draw of inductive loads such as electric motors depend in part on frequency. Current increases as frequency decreases and low generator RPM can burn out electric motors.
Like most things, there are high-quality expensive generators and economy designs. Some design differences affect service life, duty cycle, surge handling capacity etc. and others affect quality of the AC. It's a good idea to examine the power needs. People who want to run electronic equipment may need high quality power and also need to pay for a generator that produces it. Dairy farmers have different needs in a generator. Homeowners who have heat-pumps as the sole heating need to a generator that manages startup surges.
The PTO generators likely to be found at a tractor dealer likely are designed for dairy farm use, and they will be expensive. Compressor and pump surges are going to be more extreme than in most home heat pumps. Places like Northern Tool likely have economy generators in PTO models that are more suited for typical homeowner needs. I'm not sure that I'd want to put 100's of hours on an expensive tractor engine running and economy generator though.
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3 Pt PTO generators
Brian: I have a generac 25k coupled to a kubota 2550 or a jd855. this generator is a two poled gen. unit. it works great and does keep the house and pump up and running when needed. when not needed it is kept on the small trailer built for it in the hanger. i also have the mans name that it was bought from , a generac dealer that sales wholesale. it cost me about 1700 to 1900 dollars and is well worth every penny. contact me at needed. good luck
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3 Pt PTO generators
Mark: Here's an idea that might be useful. Before I installed my generator panel I used a 100-Amp service panel on 100' of flex 100A line. The panel and a flock of receptacles wired into the panel's breakers were mounted on a piece of plywood. I used the panel in the sound and lighting buz. A 30A-panel and line would be more appropriate for my generator.
I could put as many 110V and 220V circuits and what ever receptacles I needed on the board. The panel worked OK but my generator panel is much better. The old lighting panel is useful enough at construction sites that don't have AC that I've kept it around.
For the most part, use of the thing is consistent with codes as long as nothing the board is connected to is connected to the utility. For example, the inspector who passed my generator panel and renovation work made me get rid of a twist-lock plug I put into the well pump line. Even though the lines and ground are disconnected from the utility when it's connected to the generator, there is a potential connection to the utility through the well casing ground wire. The same is true for most furnaces. Use the panel and receptacles are fairly consistent with codes, but this type of thing should be wired by somebody with an electrician's knowledge. Anybody using it should have a good understanding of grounding.
The trouble with many generators is that they provide only two 15A 110V outlets which may be quite a bit less than the peak capacity of each side of the 220V generator output. Running extension cords from each 100V outlet into power-bars gives a bunch of outlets but doesn't get the whole capacity of the generator into the two 110V circuits. The power-bars also don't provide 220V and a special extension cord is needed to provide just one 220V outlet.
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3 Pt PTO generators
Ok, are you guys saying that if I set up my tractor and generator to a certain speed and something kicks in that requires another thousand watts, that the tractor's engine governor will somehow compensate?
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3 Pt PTO generators
Mark: Lord I sure wrote a lot about generators. I got up hours before my wife did, and I guess I just wrote and wrote till we went into town for family dinner. I'm not surprised at all there are questions about what I was saying.
One HP equals about 750 watts, so an extra KW kicking in adds about 1.4 more HP to the engine load. The engine would lug and RPM would decrease unless throttle is added. The way most governors work is that weights are spun against spring tension. When RPM decreases, the springs pull the weights further in, which increases throttle to the point where rpm returns to the hand throttle setting. The weights again spin further out and throttle is decreased. That's generally the way governors on standalone generators work as well, but I suppose the ones on a generator might be a little more precise since they are designed specifically for the generator.
A governor attempts to maintain constant RPM given changing engine loads. Load switching in and out on a generator is similar to driving a tractor up and down hills. Both produce changing engine loads. Incidentally, the way a governor works makes them a good cold starting aid. Setting the hand throttle 1/2 - 3/4 in cold weather gives an initial big shot of fuel before the rpm comes up to knock back the throttle. It's sort of the diesel equivalent of a choke. Yikes, here I go just writing and writing again.
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3 Pt PTO generators
First let me admit that the last time I dealt with a governor we shook hands and talked about the good old days. That is about where my direct knowledge stops.
My impression is that my tractor (and yours)uses a mechanical governor to set and control the engines top operating RPM. I thought that it came into play only when that pre-set RPM limit was reached and more load was applied to the engine, hence the smoke we see when we really make it work.
I have seen generators in operation that would idle under no/low load circumstances and then increase throttle settings automatically when a new electrical load was applied, thereby increasing RPM and power in some self adjusting manner.
This is the difference I was alluding to above, and why I think there is a fundamental flaw in the operation of a pto generator as compared to a designed engine/generator package.
It is also the basis for my comments about either overproducing or under producing wattage using the manual throttle setting on your tractor.
Am I off track here? Is my understanding of these basic principles flawed?
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I think you're right Mark. Either you are or my governor isn't working right.
Billy
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12-24-2002, 21:34 
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