Generator PTO Generator Question

[Chuck-KY]

I'm seriouly considering purchasing a 15KW PTO Voltmaster generator. I have a 24hp lawnmower that absolutely uses gas at a alarming rate while my 790 JD sips diesel at rated pto speed compared to the gas lawnmower. I can buy a 15KW PTO generator for less than $1200 while a motor/gen set will run around $2300 and probably use twice as much fuel for an extended run time. Is there anything pro or con about the PTO/tractor combination I should know or am missing. I have a frequency meter to set gen speed with and have a smaller 6KW generator now. The governor on the small gen. is really nothing special in relation to frequency control. Really no better than on a tiller or lawnmower. I would think once speed/ frequency is set on tractor, it would have a better governor control verses the smaller gas engine, or am I missing something. I appreciate any information or experience either way in regard to the two. Thanks - Chuck

 

[JB4310]

There are alot of threads on this subject but I don't know how to link to them, I learned a great deal here while I was in the process of getting a pto gen, I got a 10 KW IMD brand.as far as the governor goes I can give my own experience, I experimented with mine on an old ford 1700 diesel and a newer JD 4310, it not just set it and go, the tractors gov will not compensate for the wide swings of 5-10 KW you will have to manually adjust throttle a little, the newer tractor was a little better but still required manual input.
If the load was constant then that obviously would be better,
Like I said there is alot of great info here, you'll have to search a little or maybe someone can link some of the threads.
Your 790 has around 30 pto hp? so 15 kw would not be to big as the gen rule is 2 hp per kw, I kinda wish now that I got the 15 kw as the heavier mass spinning probabbly makes it easier on the governor especially with a 10 kw draw, would run cooler to.

As far as the pro and con goes there's alot of that, it almost turns into a fight when really it should be just a personal preference.
this might link you to a recent discussion

http://www.tractorbynet.com/forums/attachments/129834-power-take-off-generator.html

 

[art]

Most of the time to hit the horsepower to the KW will cover you for your needs. All engines work a little different on reponse time of the load, some are quick and some are slower, some give more then enough and some are al little short on torque reponse! The two horsepower per KW should cover you! For your tester, you might not aways want to look!

 

[Soundguy]

I'd add that the larger the rotational mass of the genny and engine driving it, the less rpm/freq variation there will be when a load demand comes up.. remember the flywheel stores energy.. besides.. I'd much rather rely on the governor on my tractor than the governor on some whizz-bang (essentially) souped up gass lawnmower engine..

soundguy

 

[SPYDERLK]

The problem with many of the less expensive pto gens is the large speed increase [from 540 to 3600] that is needed. In these cases the driven gear on the gen shaft is very small. This arrangement is inefficient. These gearboxes run hot. This is an indication that a lot of power is wasted in the drive - - in the 10% range. They are still a good reliable power source, just more wasteful than a direct drive setup.
More expensive pto gensets have larger better designed gearboxes and/or use 1800rpm gens so the driven gear is a reasonable size.
larry

 

[Farmwithjunk]

I bought a PTO ALTERNATOR. Bigger HP that you're looking at, but they offer smaller pto generators too.

Medium PTO

I use the model 50/30 PTCD. Have used it behind 61HP or 95HP tractors with satisfactory results. Never used to full capacity though.

 

[Iplayfarmer]

Is there anything pro or con about the PTO/tractor combination I should know or am missing.

When that big snow storm comes through and knocks out your power, you have to choose between using your tractor to power the house or using the tractor to plow snow. You can't do both with the same tractor.

Of course if you have more than one tractor you're set.

 

[RonMar]

Where you will probably run into issues, is governor control like JB4310 mentioned. Your typical tractor governor is/does not have full authority. It only has fuel control in a narrow area around where the throttle lever is placed. What does this mean for the PTO generator user? Well if you have any really massive single loads, they may exceed the governors ability to react. Basically, the governor can't deliver enough fuel to maintain RPM for a large load increase, even though the applied load is within the engines HP capability. This is where a larger tractor might work better, as the governed range is larger in terms of HP. You of course will have to experiment to see exactly how much of an effect your major loads shifting on or off has on how well the governor can maintaion RPM/frequency.

A 15KW set is a good match for a 30 PTO HP tractor. But a 10KW set may maintain RPM better unassisted from zero to full load. Even with gearbox losses, you will probably be under .2 gallons per Killowatt per hour for fuel consumption. IE: a sustained 5KW load will cost you one gallon per hour...

 

[RickB]

When that big snow storm comes through and knocks out your power, you have to choose between using your tractor to power the house or using the tractor to plow snow. You can't do both with the same tractor.

Of course if you have more than one tractor you're set.

Anyone that can't be without power long enough to clear a driveway needs to have an automatic standby system. The difference between wanting and needing is half the trouble this world is in.

 

[BobRip]

You do realize that some appliances can be damaged by the wrong frequency and voltage. I would at least initially monitor these for each load so you know which loads present a problem. There are many variables here. For example if the generator is lightly loaded and you turn on a load you will probably have a greater voltage and frequency change then if the generator is 1/2 loaded and the same load is turned on. I don't have experience with this, but that is the theory. Does anyone here have direct experience with this? I was not sure from the other comments.

 

[SPYDERLK]

You do realize that some appliances can be damaged by the wrong frequency and voltage. I would at least initially monitor these for each load so you know which loads present a problem. There are many variables here. For example if the generator is lightly loaded and you turn on a load you will probably have a greater voltage and frequency change then if the generator is 1/2 loaded and the same load is turned on. I don't have experience with this, but that is the theory. Does anyone here have direct experience with this? I was not sure from the other comments.

I run my 12/14KW with an L2550. It holds the gen speed +/- 5% regardless of load. This has presented no problem to appliances or computers. No glitch when the air compressor or AC comes on. I have had a problem with a standalone tho, that did not run steady under light load. It caused problems with electronics due to "hunting" rpm unless the gen was carrying at least a 25% load causing the rpm to be steady.
larry

 

[Soundguy]

When that big snow storm comes through and knocks out your power, you have to choose between using your tractor to power the house or using the tractor to plow snow. You can't do both with the same tractor.

Of course if you have more than one tractor you're set.

And if you only got one tractor.. you do what everybody else does.. you practice power managment and load management.

You power up the refer's for a bit to keep them cold.. then you pump up water.. if you got a wife / kids.. you power up the water heater.. then yo power up the water again and the wee ones get a warm bath.. then you go plow snow while everybody snugles up in a big blanky till 'dady' comes back in from plowing the drive.. then 'dady' powers up the blower on the furnace and runs some heat.

No different than having a family with one car.. or more people in a house than you have bathrooms... you simply do everything in turns...



I know some pople like to have 24/7 power. we've all seen or lived next to the guy that runs alternate power the entire time the grid is down.. it's especially great when they use a cheap gasser genset.. they always have the best ( yeah right! ) mufflers!

soundguy

 

[Soundguy]

You do realize that some appliances can be damaged by the wrong frequency and voltage. I would at least initially monitor these for each load so you know which loads present a problem. There are many variables here. For example if the generator is lightly loaded and you turn on a load you will probably have a greater voltage and frequency change then if the generator is 1/2 loaded and the same load is turned on. I don't have experience with this, but that is the theory. Does anyone here have direct experience with this? I was not sure from the other comments.

There have been tons of discussions on gensets on this board over the years.

I can tell you that my 12.5kw genset delivers as clean or better power than my utility, as observed on a graphing o-scope... I'm sure milage will vary.. lots of things to add in.. different loads.. different gens.. different power sources for these gens..

IMHO.. large inductive loads will be the biggest issue for frequency and laod control.. not simple ressitive or electronic loads like switching power supplies.. which are by design.. EXTREMLY fault tolerant of input power..

soundguy

 

[BobRip]

I found that it is best to supply power to the refrigators for as many hours as possible. Mine needs to have power at least 50% of the time to stay cold. If you run it less the temperature will go up. This does not mean to run it 24 hours a day. That takes way to much fuel besides the noise, wear, and aggravation of refueling. Also be prepared to store a lot of fuel even with a diesel. You will put a lot more hours on it than you normally would.

 

[Egon]

go plow snow while everybody snugles up in a big blanky till 'dady' comes back in from plowing the drive.. then 'dady' powers up the blower on the furnace and runs some heat.

Have you been plowing snow soundguy??? Or did you move ???

The peanut gallery awaits!

 

[Soundguy]

I found that it is best to supply power to the refrigators for as many hours as possible. Mine needs to have power at least 50% of the time to stay cold. If you run it less the temperature will go up. This does not mean to run it 24 hours a day. That takes way to much fuel besides the noise, wear, and aggravation of refueling. Also be prepared to store a lot of fuel even with a diesel. You will put a lot more hours on it than you normally would.

Different equpment will have different needs... my chest freezer ( sears) can get by with only 1-2 hrs a day IF if it full and kept closed.

As for the refer.. freezer section gets all the perishables hat can be safely placed in there.. and other risky consumables are always used first to reduce power / cooling needs... least that's how we've always done it here in a warm state.

soundguy

 

[Diamondpilot]

This is a Ford GM fight here. I see pros and cons to each. I personally ended up buying a Troy Built stand alone genny. It is 8,550 watts and runs everything in my home very nicely except the 3.5 ton AC unit. I have a $10 garage sale window unit as a backup now. I do have a well and my furnace is propane as is my water heater.

We loose our power bi-monthly here. I have ran 8 days straight in the winter of 2005 on the genny and a few times 2-3 days at a time. I have averaged 9 gallons per day on this genny. When I start it it runs for 2 days at a time. I then shut it down, change the oil, check things over, fill the tank and back off and running. It has never let me down and in my opinion is very efficent at 9 gallons per day or .375 gallons per hour. By the way I keep 70 gallons of gas on hand at my home and at least 100 gallons of diesel for the tractor and truck if needed. When we lost power for 8 days I had to drive nearly 120 miles to get fuel. I learned from that.

Yes, I would like to have a pto genny but this was the right choice for me. It has been used at my home, lake property, in the woods, to run one of my welders from the bed of my truck, and at my sisters place when she lost power after a tornado. 75% of the time I have needed the genny I needed the tractor to do storm cleanup of some sort.

Again, I will buy a pto genny some day but I will always keep this 8.55kw Troy Built around. Its just too good and now owes me nothing.

Chris

 

[Egon]

least that's how we've always done it here in a warm state.

Plow snow or a warm State? Which is it Soundguy??

Peanut gallery still awaits!

 

[Iplayfarmer]

And if you only got one tractor.. you do what everybody else does.. you practice power managment and load management.

You power up the refer's for a bit to keep them cold.. then you pump up water.. if you got a wife / kids.. you power up the water heater.. then yo power up the water again and the wee ones get a warm bath.. then you go plow snow while everybody snugles up in a big blanky till 'dady' comes back in from plowing the drive.. then 'dady' powers up the blower on the furnace and runs some heat.

No different than having a family with one car.. or more people in a house than you have bathrooms... you simply do everything in turns...



I know some pople like to have 24/7 power. we've all seen or lived next to the guy that runs alternate power the entire time the grid is down.. it's especially great when they use a cheap gasser genset.. they always have the best ( yeah right! ) mufflers!

soundguy

I'm not saying that's any kind of deal killer. I'm just saying that it's a difference between a standalone generator and a PTO Generator.

I'm interested to hear more of the pros to a PTO Genny. Anytime I've looked at them it just seems that an equivalent standalone can be had for cheaper. So why go to the extra expense to tie up your tractor?

 

[Soundguy]

I'm not saying that's any kind of deal killer. I'm just saying that it's a difference between a standalone generator and a PTO Generator.

I'm interested to hear more of the pros to a PTO Genny. Anytime I've looked at them it just seems that an equivalent standalone can be had for cheaper. So why go to the extra expense to tie up your tractor?

I don't know of any place i can buy a standalone for cheaper than a ptogenset... I made a post about this in another thread.. I looked in 2 industrial catalogs.. the price difference for the cheapest standalone compared tot he pto genset.. at even KW.. the pto genset was still cheaper.. per KW.. and that was comparing it to a no-brand chinese standalone. All the other more common standalones were 1.5 to 2x$ perKW vs the ptogen.

It may be different in other states.. but here... ptogen is the cheapest KW's you can make..

soundguy