Generator NorthStar PTO Generator Question

[AndyMA]

I start a 1.25 HP well with a 5 KW generator (but it is marginal), so you should be OK.

At 746 watts/hp a 1/2 hp pumpis draws only 373 watts or .373 kw. Even assuming 10x starting current (which is overstated) that's only 3.73 kw surge. There's also a difference between generators driven by high hp diesel engines where you have excess hp available vrs small 5 KW gas driven generators which typially have very little if any excess hp. A 5 kw generator 5,000/746 = 6.7 hp at 100 efficiency.

Andy

 

[zzvyb6]

I run a 50kw pto generator off my 38 hp JD. Used to run it off my 18hp Yanmar, no problems, ever. It was on a trailer, though. Only technical recommendations for the driveshaft angles is that input shaft and output shaft should be parallel in 2 planes for constant velocity. Yes, flipping can be done under 2 circumstances: adding or removing a huge load suddenly. If done gradually you should have no problems. I know of several people who keep their alternators in dog houses. Main concern with these deals is the proper sequencing of putting the device on-line and removing it from the house grid. You can get a "breakout box" installed in your house to prevent lineman from getting fried. This is an "either/or" device to segregate Edison power from tractor power. Other than that, you will find many other uses for a tractor generator: remote welding, hedge trimming, electric pressure washing and other uses that you have not yet dreamed of. You really ought to watch rpm (60 Hz) for any motors, and voltage (110 - 120) for other stuff. I even run the house AC units on this unit (dogs complan otherwise).

 

[Glowplug]

Northerntool does have a trailer designed specifically for the Northstar generators. They bolt down on it so that they don't torque sideways.

What are you planning to use the generator for?

 

[John_Mc]

A 5 kw generator 5,000/746 = 6.7 hp at 100 efficiency.

But in the real world, you'll get something like 2/3 efficiency (67%) when converting mechanical HP output from an engine to electrical KW out from the generator, so you are back to needing about 10 HP engine for about 5 KW continuous from a generator (10 HP x 746 Watts/hp X .67 efficiency = 4998 Watts). Hence the "2 HP for every 1 KW of output" rule of thumb.

Efficiencies do vary, and there are a lot of other design considerations which can efect things like surge capacity, but if you look at the continuous (not surge) ratings of most of the generators you see advertised, you'll see that most are pretty close to the 2 Hp per KW of output range. My 4 KW Generac is powered by a 7.8 HP gas engine, for example.

John Mc

 

[Glowplug]

But in the real world, you'll get something like 2/3 efficiency (67%). . . . .Hence the "2 HP for every 1 KW of output" rule of thumb.

Northstar's 27.5kW generator requires 48hp. 1.75HP/1kW. You are correct!

Northerntool does have a trailer designed specifically for the Northstar generators. They bolt down on it so that they don't torque sideways.

Northstar PTO Generator Trailer

 

[BobRip]

But in the real world, you'll get something like 2/3 efficiency (67%) when converting mechanical HP output from an engine to electrical KW out from the generator, so you are back to needing about 10 HP engine for about 5 KW continuous from a generator (10 HP x 746 Watts/hp X .67 efficiency = 4998 Watts). Hence the "2 HP for every 1 KW of output" rule of thumb.

Efficiencies do vary, and there are a lot of other design considerations which can efect things like surge capacity, but if you look at the continuous (not surge) ratings of most of the generators you see advertised, you'll see that most are pretty close to the 2 Hp per KW of output range. My 4 KW Generac is powered by a 7.8 HP gas engine, for example.

John Mc

The 5 kw generator does have a 10 HP motor. Most generators that I have seen have abouy 2 HP per Killowatt.

 

[bucmeister]

Having the "either/or" switch is the only way to be "in code" and legal. I know of many that don't, however that does not change the issue.

With the gas powered standby gensets I have always looked at the HP of the motor and cut it in half to determine the continuous output and I am guessing that the deeper stronger torque of the diesel engines lets you get by with a bit more on the tractor driven generators.

 

[MarkLeininger]

I have that same generator and run it off my Kubota B2710. I mounted it on a cheap trailer I bought at Menard's for about $75. It turned out to be almost exactly the right height for my PTO output. I have a ball hitch mounted on my tractor that I use to pull the trailer. When the power goes out, I get it out of the shed with the tractor, pull it next to the garage, and run a cord I made from the generator into my power feed.

 

[N1ST]

Thanks for the helpful info everyone. Regarding fuel. I read somewhere to expect .44 gal / 10 hp for diesel. Sounds like the gen needs 540 pto rpm which according to MF requires the engine to run at 2532 rpm (2600 rpm max). Any estimates on the fuel burned per hour for the 22.5 hp engine? Sounds like it should be < 1 gal/hr?

Also, do I need to use a freq counter to know where to set the tractor idle or is the gen very forgiving?

 

[AndyMA]

Also, do I need to use a freq counter to know where to set the tractor idle or is the gen very forgiving?

In an actual generator, not a DC generator with an invertor, there is an exact reletionship between generator RPM and output frequency.

Andy