Generator PTO Generator

[Soundguy]

I figure the 13 hp gas generator I have is going to be cheaper to operate than running my 49 hp diesel tractor at almost maximum RPS's in order to get 540 pto rpm. Plus my generator has a kickdown that when their is not any power draw it kicks down to an idle. then kicks back up as current needs increase.

Hmm.. I wouldn't automatially ssume that a lawnmower engine is going to be superior in fuel economy to a nice diesel tractor.. remember.. rpm of your tractor is not what uses fuel.. it's hp used.. p used will be determined by electrical load.. that load, in an equal comparison to the 13hp gasser nd the diesel.. just because yor engine is rated at 49 hp does not mean you are making it if.. say.. it only needs 13 hp... that means your fuel usage should pretty closely track hp usage.

I know my 12hp rider lawnmower DRINKS gas compaired to my larger diesel tractors looking at work done.. ie. amount of grass cut. 5g of diesel cuts 10ac of pasture for me... that rider cutting those 10ac will suck down a whole lot more than 5g of gas!!.. I've never been able to get more than an hour of runtime out of a gallon of gas on that rider... and it'l take a whole lota hours to cut 10ac .. so you can see where that fuel savings theory just went! Fuel used pretty closely tracks work done on n average diesel... that same 5g of fuel oil runs my 95hp/15' mower for 2 hours.. or the 70hp/10' mower for about 3 hrs... both eilding a 10ac cut.... I've used the 95hp tractor on the 10' mower used the same fuel and ran the same amount of time as the 70hp tractor..

soundguy

 

[JB4310]

remember.. rpm of your tractor is not what uses fuel.. it's hp used.. p used will be determined by electrical load.. .. just because yor engine is rated at 49 hp does not mean you are making it if.. say.. it only needs 13 hp... that means your fuel usage should pretty closely track hp usa
so you can see where that fuel savings theory just went! Fuel used pretty closely tracks work done on n average diesel....

soundguy

I guess that's what most people including myself have trouble wrapping their head around, and the reason every newbie (including myself) with a pto gen wants to know how they can slow down their engines with some kind of pto gear box.
Still, wish I had the 2 speed pto so I could at least try it on lite loads.
JB.

 

[Egon]

Hmm.. I wouldn't automatially ssume that a lawnmower engine is going to be superior in fuel economy to a nice diesel tractor.. remember.. rpm of your tractor is not what uses fuel.. it's hp used.. p used will be determined by electrical load.. that load, in an equal comparison to the 13hp gasser nd the diesel.. just because yor engine is rated at 49 hp does not mean you are making it if.. say.. it only needs 13 hp... that means your fuel usage should pretty closely track hp usage.

Sure wish my truck had heard of that philosophy on fuel usage!

It has gotten 14 MPG moving a 24000 pound load over some distance. Now using the above philosophy it should achieve almost 50 GPM just moving itself around at the same speed. Sadly that don't happen!

Must be I figured something wrong??

Orr??? is it just that I can't use that type of comparison because it don't abide by the philosophy??

 

[Northland]

I think you will be amazed what your utility sells you as power.. depending on the motor loads in yor house.. and the age of those appliances.. and where on the line you are in your grid.. you can get some pretty scarry stuff.. like 130v line voltages.. and up to 2hz excursions.
soundguy

You got that right SoundGuy! I am near the end of the line in a very rural area and I lost several electronic devices due to surges before I put everything on surge supressors.

Lots of sensible responses from you to other posts as well

 

[SPYDERLK]

Lotsa sense on the thread lately. A few thoughts:
1] Lawnmowers chop grass finer than tractor implements. This accounts for some of the apparent inefficiency when comparing.

2] Using the 1000rpm PTO to run a 540 gen is a setup that requires very close engine speed control. Approx twice as close to get equal frequency stability because engine speed changes have 2x, ie 1000/540, effect on gen speed due to the pto gearing. Worse, this high control accuracy is required at low engine rpm. It takes a very special governor to hold well across the load range. This setup would work fine on steady state loads tho.

3] Most gens do not have high surge capacity because the manufacturer pushes the nameplate rating up to near the max capacity of the windings and field metal and just provides the cooling to keep things happy. Usually only about 15% is available above this for a surge rating. Beyond this the voltage output drops quickly even if generator speed is maintained.

4] ~6.5 : 1 gearboxes [3600/540] are pretty inefficient. Much nicer to have an 1800 rpm gen -- or else one designed for 1000PTO.
larry

 

[MessickFarmEqu]

Unfortunatly.. lots of myth here.. and not as much fact.

Reality is.. that -MANY- common electronics with switching based power supplies ( triacs ) are EXTREMLY fault tolerant when dealing with over/under frequency and voltage.

Two weeks ago we lost a 37" LCD TV becusae we killed the power supply because we overdraw our 400AMP electrical service at work. Our phone system also has a tendencay to wack out when we're doing too much. I've spent thousands on battery backup and AVR equiped battery backup systems to protect servers. In a home things maybe different, but my experience has been very different.

 

[atgreene]

I guess that's what most people including myself have trouble wrapping their head around, and the reason every newbie (including myself) with a pto gen wants to know how they can slow down their engines with some kind of pto gear box.
Still, wish I had the 2 speed pto so I could at least try it on lite loads.
JB.

I have a 540 and a 750 setting on my Kubota (50 - hp). When I run my 16 k generator I have found that the 750 setting with the tractor idled back to 540 rpm will not govern itself close enough to work well. I have a hertz meter set-up on the generator and can monitor the load/slow down when things like the furnace kick on. At the 540 setting it works better and the governor keeps it where it needs to be as loads dictate.

As for fuel, my tractor burns less than my 5k gas genny did. I figure less than a gallon of fuel per hour, and have actually found nights where it ran all night with light loads and only used around 1/2 gallon per hour. If I shed some more loads I could probably gain a little beyond that.

 

[Smokin Diesel]

Sure wish my truck had heard of that philosophy on fuel usage!

It has gotten 14 MPG moving a 24000 pound load over some distance. Now using the above philosophy it should achieve almost 50 GPM just moving itself around at the same speed. Sadly that don't happen!

Must be I figured something wrong??

Orr??? is it just that I can't use that type of comparison because it don't abide by the philosophy??

Apples and oranges. Weight has very little to do with MPG once you're rolling (Newton's first law). Air resistance is key, with a touch of friction from the tires. So the HP required from the engine, thus fuel milage, won't change much from empty to loaded.

 

[Iplayfarmer]

Apples and oranges. Weight has very little to do with MPG once you're rolling (Newton's first law). Air resistance is key, with a touch of friction from the tires. So the HP required from the engine, thus fuel milage, won't change much from empty to loaded.

So, Now explain why my Chevy Silverado 1500 goes from 15 mpg to 9 mpg when pulling a heavy load.

 

[Smokin Diesel]

So, Now explain why my Chevy Silverado 1500 goes from 15 mpg to 9 mpg when pulling a heavy load.

Sure. You're adding a trailer with a bunch of wind resistance and a handful of tires. Pretty much what I said above.

Think of an over-the-road semi with a dry van trailer. It can double its weight when loaded, and still stay within 10% of its unloaded milage. Or Boneville Salt Flat racers. Those cars are heavy as heck, but very slippery.

Nobody has proven Newton wrong yet.