generator horse power requirements

[sandman2234]

First off, I know the standard rule that it takes two horsepower per kilowatt of power.
However, I have a freind with a small (13/11 hp) tractor that wants to adapt a like new generator head that the gasoline engine tossed a rod. Since it was gasoline, I am going to assume that it was a 3600 rpm generator head (straight coupled). He wants to adapt this to his to his pto, which is three speed. Since he would probably use the fastest pto speed, and gear it up(sheaves and belts) to somewhere close to 3600 at close to full throttle(no tach), we are trying to figure out what the available horsepower is going to be, at the generator head.
Since the diesel engine is rated at 13, and pto is rated at 11, what is normal for the faster speeds to be calculated at, or is it the same, due to horsepower being figured at a rate of speed? Can anybody give a rough estimate what the final horsepower is going to be once it enters the generator head? (or how many kilowatts it may use of the available 8KW?)
before it over taxes the tractor?
Thanks in advance,
David from jax

 

[dex3361]

Still going to be in the 6.5KW (+-)range on a steady basis and it would probably surge the full 8 KW because of the rotating mass of the tractor.

 

[IXLR8]

Since he would probably use the fastest pto speed, and gear it up(sheaves and belts) to somewhere close to 3600 at close to full throttle(no tach)

You are going to need to get as close to 3600 rpm for the generator as possible so you have 60Hz on your incoming power. Motors will be happier and your plug in clocks will be more accurate.

 

[Mighty Dodge]

As IXLR8 said you'll need to be as close to 3600 as possible. You're lights don't care but motors and electronics do. I use a Lincoln G8000 when the power goes out. Everything in the house works (not all at once) but I have a new washer and dryer with electronic controls that won't even turn on. I guess the power's not clean enough for them.

M.D.

 

[Skyco]

As IXLR8 said you'll need to be as close to 3600 as possible. You're lights don't care but motors and electronics do. I use a Lincoln G8000 when the power goes out. Everything in the house works (not all at once) but I have a new washer and dryer with electronic controls that won't even turn on. I guess the power's not clean enough for them.

M.D.

Sometimes electronics are a pain- I bought an inexpensive Mr Coffee drip machine for my camp. Dang thing won't work on my invertor for that first cup of coffee without going out to start the generator. Ripped out the electronics and put in a toggle switch
Oddly the LCD TV and DirecTV receiver work just fine on the invertor, those are the things I thought I'd have trouble with....

 

[Bikewanderer]

First off, I know the standard rule that it takes two horsepower per kilowatt of power.
However, I have a freind with a small (13/11 hp) tractor that wants to adapt a like new generator head that the gasoline engine tossed a rod. Since it was gasoline, I am going to assume that it was a 3600 rpm generator head (straight coupled). He wants to adapt this to his to his pto, which is three speed. Since he would probably use the fastest pto speed, and gear it up(sheaves and belts) to somewhere close to 3600 at close to full throttle(no tach), we are trying to figure out what the available horsepower is going to be, at the generator head.
Since the diesel engine is rated at 13, and pto is rated at 11, what is normal for the faster speeds to be calculated at, or is it the same, due to horsepower being figured at a rate of speed? Can anybody give a rough estimate what the final horsepower is going to be once it enters the generator head? (or how many kilowatts it may use of the available 8KW?)
before it over taxes the tractor?
Thanks in advance,
David from jax

I think I would go with the larger head like you describe, but be aware that you may not have the horsepower to make it run. I think you can get away with 6500 watts continous and 8kw peak, but you'll likely have only 9 hp to run it. Plan on setting it up for around 3800 RPM, and throttle back slightly to get the right speed. The right speed will likely be around 3675-3700. I think most generators are set up for around 62/63 hz at no load.

 

[Redneck in training]

Tractor HP is measured at top governor speed. PTO speed is selected at maximum torque of particular engine. Typically the engine will have the lowest specific fuel concumption (g/kW or gal/HP) at PTO speed. So if you run the tractor faster than rated PTO speed it will have more PTO power. The trade off is higher fuel consumption per kw produced.

 

[jonyyuma]

Tractor HP is measured at top governor speed. PTO speed is selected at maximum torque of particular engine. Typically the engine will have the lowest specific fuel concumption (g/kW or gal/HP) at PTO speed. So if you run the tractor faster than rated PTO speed it will have more PTO power. The trade off is higher fuel consumption per kw produced.

Okay,So now what happens when you increase load, the gen slows down and there goes your hertz? If load falls then it goes over, pto speed will be constant since you don't have throttle attached to it.I have seen units made for the pto, but the load has to be constant to work, Right?Plus electronics hate surges, and can instantly go belly up. Jy.

 

[Redneck in training]

Okay,So now what happens when you increase load, the gen slows down and there goes your hertz? If load falls then it goes over, pto speed will be constant since you don't have throttle attached to it.I have seen units made for the pto, but the load has to be constant to work, Right?Plus electronics hate surges, and can instantly go belly up. Jy.

That was the most obvious question nobody asked yet. Does your tractor have a speed governor? Most tractors do have it. If it does have it the governor will adjust power to keep the rpm constant.

 

[jas67]

Sometimes electronics are a pain- I bought an inexpensive Mr Coffee drip machine for my camp. Dang thing won't work on my invertor for that first cup of coffee without going out to start the generator. Ripped out the electronics and put in a toggle switch
Oddly the LCD TV and DirecTV receiver work just fine on the invertor, those are the things I thought I'd have trouble with....

Get a pure-sine inverter. I have a 1KW pure-sine inverter in my camper, and it runs everything except the microwave and the air conditioner. Not only do electronics like it better, but AC induction motors, such as those in normal household fans like it much better too. With my old MSW (modified sine wave) inverter, the fans ran slower, hotter, and made a loud 60 Hz hum. I don't think they would have lasted too long running that way.

The DirectTV box probably runs on the inverter, because it likely has better power conditioning circuitry than the cheap coffee maker.

 

[Redneck in training]

Switching power supplies (without a transformer) care less what the shape of the power is. Transformers have to have a symmetrical shape of the power otherwise they heat up might burn. Most TVs, computers and home electronics in general use switching power supplies.

 

[Soundguy]

i think i'd get one of those gearboxes that steps up 540 to 3600.. like many pto gensets use.... forget belts.. YUCK! then you can actually get reliable 7k power generation...

soundguy

 

[Soundguy]

Switching power supplies (without a transformer) care less what the shape of the power is. Transformers have to have a symmetrical shape of the power otherwise they heat up might burn. Most TVs, computers and home electronics in general use switching power supplies.

older ferro ressonant supplies suffer the worst from non sine wave. however square and stepped can still be pretty usefull.. ie inverter power.

genny power will be sine.. though freq could drift.. etc..

soundguy

 

[jejeosborne]

Make sure to check the generator shaft. Some of these types of generators use a special tapered shaft that is close to impossible to adapt to. I considered a similar project and found that purchasing a new motor or entire generator was more cost effective. My plan was to use the mid-pto and mount it to the front of the tractor.

 

[chiefchicken]

Also, check to be sure the generator head has a support bearing on both ends. Many generators that are coupled directly to a gas engine use the engine crankshaft to support one end of the rotating parts of the generator.

 

[Soundguy]

that's why I'm not a fan of belt coupled gen head contraptions due to the side loading...

soundguy

 

[sandman2234]

Generator only has the single bearing but adding an additional just took half a day with his lathe/mill.
David from jax

 

[/pine]

FWIW...

I have been looking at generator heads, they come in all ranges of KW output(these are meant to be hard wired)...they can be used with gas, deisel or other power sources...almost all of them are rated at 1800 RPM...FWIW...

reference: search e-bay for "Generator Head"