hp needed for genny?

[daTeacha]

Someone is advertising a 20kw PTO generator for about $1300 in the local paper. Seems like a decent price, but how much tractor does a generator that size need? It's way more generator than I need for backup, but more power is often nice.

 

[chh]

The Tiger generator ads list 36 to 40 for a 20kw. It seems like the old 25kw I used to have claimed to need about 50. At full load it would have really worked a 50 because it would pull down a 75 hp pretty good. I have a 40kw left over from my business now, it is really over-rated for the house, but I'd rather keep it than buy another.

 

[Z-Michigan]

The generator will probably say on it what PTO hp is required. I think you can run it with less PTO hp as long as you don't try to use all 20kw. You could also look up websites of companies that make PTO generators and see what they rate.

 

[Jimbrown]

All things not considered one Kw = 1.34 HP. 20KW = 26.8HP Plus some lossess in the gen ect probably 30HP would run it. Also consider that the 20KW is probably a peak rating and not continous output. So again 30hp or so ought to run it a normal output or at least all that you will use.

 

[RonMar]

The rule of thumb for sustainable electrical output is 2HP per KW. This factors in mechanical losses and provides for engine longevity. As mentioned, you don't have to use all the KW capacity of the generator, but you do need to provide enough HP for the KW's you do use. You could put a 40KW generator on a 40HP tractor, but you are only going to be able to carry around a 20KW electrical load with it.

A slightly larger generator head is also not such a bad thing as it will run cooler since it is not at it's maximum electrical capacity and the greater ammount of copper in the windings will absorbe surge loads better. It will also have more spinning mass than necesary so will absorb heavy short duration loads such as starting a deep well pump or large A/C better than a generator operating near peak capacity. This means it will want to keep spining at a given RPM(body in motion tends to stay in motion) and have better frequency stability. This is desireable, particularly while being spun by an engine/governor that is not especially designed for stable power generation.

If you get into a grosely oversized situation such as a 40KW generator to power a 5KW average load, you will start to run into efficiency issues and just be burning way more fuel than you need to be to accomplish the job.

 

[tomd999]

Hiya,

Both my stationary 19KW/40HP and portable 7.5KW/16HP are right at the 2HP/KW range.

I checked out the Deere PTO gen last time I was at the dealer (It had a clearance tag on it, still too much to spend on a third generator) and it's 10KW and listed for the Diesel x700 and 2x20 series of tractors which are all around 20 PTO HP

My 2 cents,

Tom

 

[RalphVa]

20 kw = 27 hp (746 watts = hp). This would be at the PTO.

Questions on the 20 kw would be: is this continuous or startup kw? It's probably continuous. Any startup kw requiring more than 20 kw would likely trip the breakers on the generator and not require a bigger PTO driver than continuous rating.

Ralph

 

[zzvyb6]

There's not a minimum hp to spin the PTO generator/alternator. Turn it by hand if you can. But keeping the rpm up under the load you have plugged in will be the tractor challenge.

I run a 50 kw Winpower with 'only' 35 hp. Haven't tried plugging in the city of Brighton yet, but it serves me just fine. Tractor doesn't even ever hit the governor with my furnace, well, a/c, stove, microwave, and a can opener.

 

[CamshaftLF]

I have the tiger power 10kw my tractor at the pto is 21hp and it runs the gen set with ease. My shanty is a 2 story farm house w/ apartment on one side where my farther lives. Have a 4 zone hot water, 3/4 water pump, 3 refig,1 upright freezer, arc light, all lights in the home plus apartment, 2 a/c units,and the gen is mounted in my garage that is 36x48x12h has 23 8ft fluorescent lights, 6hp air compresser, mig weld 110, 2post car lift. The air compressor will make the tractor blow the black smoke for a bit till it starts then all is fine the well pump will only make it grunt very little. The gen has the L E D lights that I really like take the rpms up till the green light is lit and thats it. My pto rpms for 540 is 2400 the green light comes on the gen at 2100 on my tach. I'm very satisfied with the tiger power and I researched it for over a yr before I purchased it.

Just my 2 cents from my personal experiences. Hope this helps with any decisions your going to make.

 

[Builder]

I have the tiger power 10kw my tractor at the pto is 21hp and it runs the gen set with ease. My shanty is a 2 story farm house w/ apartment on one side where my farther lives. Have a 4 zone hot water, 3/4 water pump, 3 refig,1 upright freezer, arc light, all lights in the home plus apartment, 2 a/c units,and the gen is mounted in my garage that is 36x48x12h has 23 8ft fluorescent lights, 6hp air compresser, mig weld 110, 2post car lift. The air compressor will make the tractor blow the black smoke for a bit till it starts then all is fine the well pump will only make it grunt very little. The gen has the L E D lights that I really like take the rpms up till the green light is lit and thats it. My pto rpms for 540 is 2400 the green light comes on the gen at 2100 on my tach. I'm very satisfied with the tiger power and I researched it for over a yr before I purchased it.

Just my 2 cents from my personal experiences. Hope this helps with any decisions your going to make.

That's really useful info. So you need to run 2100 RPM to get the tiger power to run at max output? You have the driveshaft run through the wall of your shop to the gen? The gen is then hardwired to your breaker panel?

Thanks.