3PT Generator Question

[zoltanthegypsy]

As I understand inverter performance, they regulate output voltage AND frequency independent of the prime mover's rpm. They raise their engine's rpm when the total power being used requires it. It's that engine-speed-regulating function that would be difficult to connect to the tractor's engine so that it would be accurate and "play nice" with the rest of the inverter....

Good point. Since the tractor's revs would have to stay up at all times, the small advantage of not having to maintain _exact_ revs wouldn't amount to much of an improvement.

Thanks for the thoughtful reply.

Z.

 

[RickB]

Another point I've noticed - a tractor's 2-speed pto can run a generator on the higher speed (lower engine rpm) but only if the tractor is big enough so changes in load don't affect it much. My 60 hp can loaf at 1700 rpm but but the 35 hp has to use the lower pto speed (engine at 2450 rpm) to be stable under changing load.

My Case 885 with 2 speed PTO can run the whole house easily in PTO high which is 540 PTO RPM @ 1100 ERPM and it burns about 1/2 GPH of fuel. Unless during a midsummer outage we decide to run the central air conditioning. Then I need to run it in the normal PTO setting of 540 PTO RPM @ 1800 ERPM.

 

[displacedPA]

Could I run my PTO of my B2320 at the high setting which is 960 then lower the rpms on the tractor until i reach the 540 range for the pto gen. i would not use it for a large duty cycle just on and off to run the well ect. ?

 

[psdx]

Could I run my PTO of my B2320 at the high setting which is 960 then lower the rpms on the tractor until i reach the 540 range for the pto gen. i would not use it for a large duty cycle just on and off to run the well ect. ?

Depends... The generator gearbox is meant to supply power at the proper frequency with the input to the gearbox spinning at 540 rpm. So first, you need to have a way (either built into the generator or with a separate test set) to validate the generator output frequency (unless maybe your tractor's tach has a mark for getting 540 with the selector set at 960).. Second, this assumes that your tractor generates enough hp at the lower engine rpm to keep the generator spinning at a constant speed when the load varies. You can figure about 2hp per kw of generated power. You can find your engine's rated hp at whatever speed it's going when you've throttled it back by looking on the web for Kubota engine specs and getting it from the hp curve chart.

...last point, your well pump is almost certainly the one item in your home with the largest electrical load at start. A well pump can draw as much as 6 kw to start. Your PTO power at full rated speed is easily capable of generating sufficient power to start your well. But if you want to seriously consider this, please post your well pump's hp rating and manufacturer name, e output rating of your PTO generator, and what the engine rpm on your tractor would be to spin the PTO at 540, when your speed selector is set at 960.

 

[PHILIP8N]

Could I run my PTO of my B2320 at the high setting which is 960 then lower the rpms on the tractor until i reach the 540 range for the pto gen. i would not use it for a large duty cycle just on and off to run the well ect. ?

Yes, As long as the tractor engine can keep up with the electrical demand and not loose rpm and begin to lug. Mind the in-rush load of the well pump. Philip.

 

[displacedPA]

yes i will have to investigate that perhaps I would run at full rated rpm to run the well pump. Then run at the lower rpm for everything else. thanks

 

[PHILIP8N]

Personally, I would just run at high engine speed and not worry about it. What are your engine speeds when running at 540 pto rpm? What are you saving? Fuel, not so much. Engine wear, some. But, a well maintained Kubota engine should last around 8000 hours before rebuild. Can you accumulate that in your lifetime? I have a 10kw gasoline portable backup generator I use to run our house in power outages. I have had it since 2000 (bought it on a deal after the electronic world ended as we knew it on Dec 31, 1999.). It runs 3600 rpm, I keep it well maintained, excersise it monthly, and it has just over 200 hours on it. What tractor do you have? We should be able to find an engine data sheet that will show you horsepower output and fuel consumption at different rpm's. That would help your decision. Philip.

 

[displacedPA]

I have a B2320,

I just looked at some engine data sheet and your right im not saving that much... and in reality your right I keep up on my maint. so what am I even worring about... I also do not need the gen. all the time so the tractor will not be run that much either.

 

[PHILIP8N]

I have a B2320,

I just looked at some engine data sheet and your right im not saving that much... and in reality your right I keep up on my maint. so what am I even worring about... I also do not need the gen. all the time so the tractor will not be run that much either.

Are these the same engine data sheets you found? You still need to know engine rpm at your two 540 pto output speeds to use the curves. Philip.

 

[chiefchicken]

I picked up a 10kw from IMD (a TBN advertiser) about 2 years ago. Excellent quality, and all in all it was the best price around. Nothing "made in China", the generator head and gearbox are made extremely well. They sold me an entire package that included generator, gearbox, 3 point hitch frame, and PTO shaft.

IMD - PTO Generators

After Hurricane Irene, we were out of power for 8 days, and I ran the generator approximately 5 hours per day. No complaints at all. On my BX2350, engine rpms are at 3050 for proper generator output.

For the first 4 days, there was NOTHING around us that was opened. Having a diesel tractor spinning my generator was great because all I had to do for fuel was transfer a few gallons each day from my heating oil tank (through a filter, of course).

When I wasn't providing power, the generator just stayed on the back of the tractor and provided a nice counterweight as I cleaned up the yard.

You have to weigh out what makes the most sense for you. If you are going to need to use the tractor (loader, etc) and the generator at the same time, you may want to consider a stand alone unit.

For me, the benefit of having the generator powered by my tractor work well. Your mileage may vary!