Generator PTO generator speed

[RickB]

*I'd just prefer to keep it out of the weather when/if at all possible.
My idea of a Gen is to place it in the garage next to or close to the circuit breaker electrical panel.L . B .

A perfect recipe for CO poisoning.

 

[Mark_G]

A perfect recipe for CO poisoning.

Thank God I live in VA and not CO!

 

[LBrown59]

A perfect recipe for CO poisoning.

How can that be when the building is not attached to the house.?

 

[Soundguy]

Where is your tractor going to be setting through out an ice storm while it's powering the Gen.?
This is just one of the problems I see with a P T O Gen.!
L . B .

Wherever it needs to be is the correct answer.

soundguy

 

[Soundguy]

Mine is sitting in the same place it always sits. Why, is your allergic to rain or ice?

Remember.. LB has those pretty lil orange twins..

soundguy

 

[Soundguy]

To add to that.. many items that are 50/60hz are also based on switching power supplies.. IE.. ever look at a new wall wart that says 90-240v 50/60hz.... that means it's overseas capable with a plug adapter.. and the triac's do all the 'hard' work.
Most computer power supplies won't even 'brown' till under 90vac.. etc.

electrical motors and -old- electronics will likely be the most sensitive to frequency and voltage problems..

soundguy

Jeff, I'm going to have to respectfully disagree. In fact, many devices are rated 50/60 Hz, because they'll do just fine either way. What typically burns up (non-resistive) electrical equipment is low voltage which results in low power so the equipment ends up drawing significantly more current to drive the load.

One thing to note, with most of the capacitor excited generators on the market today, the voltage (up to rated load) will very much fall in line when the frequency is adjusted to ~60 Hz and vice-versa. As such, adjusting for the voltage is usually a fairly accurate way (+/- a few Hz) of setting up the generator.

One side note: There is a device called a "Kill A Watt" available that runs about $20-$30 and can be plugged into any outlet to give you not only Hz, but all kinds of other power useage information. It's designed to help you track how much power a particular device, such as a freezer, is using over time, but it has the added bonus of frequency, voltage, current, power factor, among other measurements. I got mine on eBay, but they're available elsewhere. They also make an advanced unit that costs more and has some added features, but I'm not familiar with it.

 

[Soundguy]

Frankly.. i don't think you understand how a switching supply really works!

switchers are QUITE voltage tolerant during brown periods.

soundguy

I am in agreement with Djradz. voltage excursions are far more an issue than freq excursions are. Purely resistive loads such as heating elements don't care about frequency. But the first thing pretty much all electronic devices do these days is take that AC and convert it to DC using either a rectifyer or switching power supply. Neither of which particularly care what the frequency is either. But depending on the design, they will cook themselves trying to maintain their regulated design output when the input voltage drops low. Inductive motors will run at a slower or faster speed depending on frequency, like the electric clock example given earlier.

I also highly reccomend the Kill-a-Watt. IMO, no one who makes their own power should be without one. One of the best features is that it plugs into any wall outlet, so you can check the generator voltage and freq output from whatever room in the house you are occupying. When on generator power, I keep mine plugged into a living room wall outlet most of the time. It gets moved to the kitchen when we cook as that really can use every watt of my 3KW available. Because of the mechanical governor on my engine(much like that of a tractor), I can also gauge engine load by the frequency. I set my generator RPM for 62HZ no load, and I am at full engine load at 58HZ. It has proven to be a pretty linear progression, so at a glance, I also know what the generator load is.

The Kill-a-Watt is also excellent for measuring appliance loads to help determine exactly what your electrical demands are. You can find them online at E-bay and such, and Harbor Freight tools also usually has them on the shelf in their stores as well as their website.

 

[Soundguy]

*I'd just prefer to keep it out of the weather when/if at all possible.
My idea of a Gen is to place it in the garage next to or close to the circuit breaker electrical panel.L . B .

Yeah.. would want any ag equipment to actually see weather.. like it does on the dealers lot...

soundguy

 

[Soundguy]

For you guys that obviously know a lot more about electricity than I do, is it safe to say that if I have the frequency dialed in to 60Hz that my voltage is going to be correct, too?

I know that a lot of things are rated for 50/60 Hz, but I also know that a 50Hz rated motor running on 60Hz power has a short life ahead of it. I assumed the same was true in reverse. Sorry I misspoke.

Yep, unless the genny is malfunctioning.

soundguy

 

[Tom_Veatch]

Not to hijack, but my tractor has 2 PTO settings one is the standard 540 and the other is 1080 (I think thats right). The dealership told me it was for over seas and not to use it. Could I set the PTO to this position and run at half the RPM to get the 540 RPM needed?

Tom

The answer to the question you asked is obviously, "Yes". To get a specific PTO speed in the "high range" would require only half the engine RPM it would take to get that same PTO speed using the "low range". However, I think your question is really whether or not you could run a generator using that technique.

The generator needs a certain amount of input power at a specific RPM to function properly. That power requirement is the same regardless of what PTO gearing is used. But whatever gearing is used, the PTO output shaft has to be turning at or near 540 RPM.

Your tractor has a "high range" gearing ratio that turns the the PTO output shaft at 1080 RPM at the tractor's engine "PTO Speed". I don't know what that throttle setting is for your tractor, but let's assume its somewhere around 2200-2400 engine RPM. So using the "High range" to get 540 RPM at the PTO to match the generator's requirements, your tractor engine RPM will have to be 540/1080 = 50% of the engine "PTO Speed", or using the example, 1100-1200 engine RPM.

Now, assume the generator operates at 100% efficiency (fat chance of that). In that case, for each KW produced by the generator, your tractor has to supply 1.34 HP at the PTO output shaft. But nothing works at 100% efficiency. Let's assume the generator runs at about 80% efficiency. That is, only 80% of each HP fed to the generator comes out the other side as electrical Kilowatts. That means, instead of 1.34 HP per KW required at the PTO output shaft, you'll need about 1.68 HP per KW. Now, that's not engine power, that's PTO power. If you further assume that the tractor is about 75% efficient in getting engine power out the PTO shaft, you'll need about 2.2 engine HP per generator KW. The rule of thumb is about 2 HP per KW. The above shows how that rule of thumb came about. The efficiency numbers I quoted are strictly off-the-wall estimates, but I don't think they are too far off.

So the real question is, "Will your tractor engine develop enough HP at 1100-1200 RPM to provide the input power required by the generator?" The more power you take out of the generator as electricity to run whatever it is you want to run, the more power you have to put in the generator from the tractor's PTO. As an example, to fully utilize a 10 KW generator, your tractor would have to supply 20 to 22 HP at the PTO. If you're only using 5 KW, even if it's a 10KW generator, you would have to supply only 10 to 11 HP at the PTO.

If your tractor can supply the required power at what is not too much more than idle RPM, you're good to go. If not, the generator will lug the engine down, possibly even to the point of stalling. In any case, the results will be highly unsatisfactory.

Without a set of HP vs RPM curves for your tractor and good efficiency numbers, there's no way your question can be answered "Yes" or "No" with any degree of confidence.