PTO generator sizing

[CMV]

Neighbor in the house behind us has the automatic natural gas whole-house generator. It is a really nice setup. When it runs/exercises pretty quiet for amount of power it's producing. Hers is a medium sized one about 14K and runs everything.

I like hers but wonder in an extended outage how long will the natural gas utility be up? In the 12 yrs we've lived there power hasn't been off more than maybe 16 hrs so I haven't been able to see how it works for a longer period. I'm messing around with gas cans & extension cords & she just goes on about her day

I like your propane idea too since that wouldn't be depending on a second utility. Bulky container & high cost to operate, but would run everything for probably 12 days straight or so with a 500 (400) gal propane tank and minimal fuss.

 

[Jcoon]

Here she is, paid 1500 for it. Surprisingly it is very quiet!

 

[TerryR]

If I had it to do over again, I would consider a propane powered whole house automatic standby generator. If you wire the transfer switch yourself, the cost is maybe twice what you would pay for a big PTO generator. I'm not getting any younger and the automatic feature would make it worth the $$ IMO.

If you heat with propane, that's the best solution in my view. We have a 1500 gal. propane tank (because it can be difficult to get up our steep driveway in winter) and a tri-fuel generator running on propane. It will run "forever" if needed, no need to get the tractor out or rotate fuel. Our outages are typically in winter when the tank has recently been filed. Just start it and it runs.

 

[rhunt]

Jcoon, unit states 25kw. It takes 2 hp to generate 1000 watts, so if you where to generate 25 kw you would need 50 hp. Most times when we use generators, we do not run them to their max output, just enough to run whatever is needed. So you could run this unit with your set-up, just not full 25kw. Remember, your pto horsepower is most always less than your tractor horsepower.Bob

 

[Jcoon]

Absolutely that’s the plan! I will never need 25,000 Watts, if. I had everything on in my house I may tax out at 15,000 Watts, I can always turn my tractor up anyways, they are the same engine from the 35 hp up to the 55 hp. Manual calls for 45 hp FYI.

I can’t even buy the northern tool generator assembly alone for less than 1800 shipped to my house, this came with everything for 1,500 and it’s a 1800 RPM gen head. Good deal!

 

[bdhsfz6]

Jcoon, unit states 25kw. It takes 2 hp to generate 1000 watts, so if you where to generate 25 kw you would need 50 hp. Most times when we use generators, we do not run them to their max output, just enough to run whatever is needed. So you could run this unit with your set-up, just not full 25kw. Remember, your pto horsepower is most always less than your tractor horsepower.Bob

If you power a large generator with less horsepower than recommended, you must monitor the line voltage and exercise good power management. If the generator load exceeds what the tractor can maintain, the RPM will slow causing the line voltage to drop. This could cause major damage to some appliances. With thermostats, automatic timers, more than one person turning appliances on and off, etc., it isn't always obvious what the electrical load is at any given time.

If your rated generator capacity matches your tractor PTO output, the generator circuit breaker will trip before any damaging line voltage drop occurs.

 

[zzvyb6]

I'd be more concerned about a drop in line frequency than voltage, although the 2 will go hand in hand. There is a plethora of charts and tables on-line to use for figuring out how much capacity is needed. It might also be necessary for you to educate the family about special use considerations on electrical demand if they are too stupid to realize that it's an emergency situation going on in the home and to cut down on big current devices (cable box, oven, microwave, space heaters, home theater, 200" tvs, rail guns, rocket launchers and your 1.5 megawatt 200' lighted Christmas tree.

 

[Jcoon]

My entire load is about 15,000 Watts, and that’s everything I have on at once. And the water heater doesn’t run in the winter so take that out of the 15,000. Tractor can make about 15,000 Watts.

 

[Sawyer Rob]

If you power a large generator with less horsepower than recommended, you must monitor the line voltage and exercise good power management. If the generator load exceeds what the tractor can maintain, the RPM will slow causing the line voltage to drop. This could cause major damage to some appliances. With thermostats, automatic timers, more than one person turning appliances on and off, etc., it isn't always obvious what the electrical load is at any given time.

If your rated generator capacity matches your tractor PTO output, the generator circuit breaker will trip before any damaging line voltage drop occurs.

I've never over loaded my 12.5 pto hp tractor with my 15kw pto generator, it just hums along nicely powering my home...

IF I was worried about THAT, I'd put a breaker the size my tractors pto will put out, between the gen and the house. Very easy to do...

That way, if I exceed the tractors out put, the breaker will let go.

SR

 

[Sawyer Rob]

I can always turn my tractor up anyways, they are the same engine from the 35 hp up to the 55 hp. Manual calls for 45 hp FYI.

Only thing is, it may be (and often is) more than just "turning it up"...

Many times it's turning it up WITH bigger injectors and some other things...

I see this all the time...

SR