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RodInNS 10-27-2009 19:17:16 216.118.158.123 250874 Report to Moderator	When you max out the generator, you'll find the problem... We run a 25 KVA and it makes a 50 hp tractor snort. The 70 and more get along fine but I wouldn't want to try it at idle speed with a 1000 shaft. It's a pretty basic torque calculation. If you take the engine speed that the tractor must run at, then figure out what torque the engine is making at that speed, you can quickly figure out what power it's making. It would also generally be below it's peak torque so it's not likely to have much response... Rod [Reply]   [Send Email]
VaTom 10-28-2009 06:35:35 216.12.124.38 250897 Report to Moderator	Re: PTO Driven Generator in reply to RodInNS, 10-27-2009 19:17:16   Rod, all depends on the load. I sometimes run my 25KW generator off my 1000 PTO, and that's from only a 25 hp tractor. Nice and quiet. When my load's heavier, I use the 540 rpm/high engine rpm. I can't draw 25KW with the small tractor, but never been a problem. Mostly it powers a 12 hp planer and 5 hp chip blower, not on 1000 PTO, and started sequentially. Mazemeister has the right idea: if it works, use it. I've got a substantial mismatch between tractor and generator, no problem. Generator was ridiculously cheap, so I bought it. Suits my needs.   [Reply]   [No Email]
RodInNS 10-28-2009 10:22:25 216.118.158.123 250916 Report to Moderator	Re: PTO Driven Generator in reply to VaTom, 10-28-2009 06:35:35   The point is... that with an 85 HP tractor and a fully loaded generator, it won't work unless the generator is overspeeded. Most 85 HP tractors will produce mabey 40 hp at a fast idle, which is where it would need to run for 540 with a 1000 shaft. The 806 might do it OK because it's a 95 horse tractor that in all probability made more anyway without accounting for the smoke screw getting backed out about 20 percent... so couple that with a generator not fully loaded and you get away with it. The fact that you can do anything with a 25 HP tractor on a 25KVA gen tells me you had no laod on it at all. I sometimes run ours on a 45 hp tractor for light loads of short duration and it works it hard. The 50 hp can handle it at full power but it's working very hard. We generally stick our 86 HP rated (turned to 105 hp) for long hauls. Start a 4 horse compressor with some other loads on the go and it wakes her up too. She's not working hard but the sudden load will make her jump. If that was at idle speed she'd be down for the count. Rod   [Reply]   [Send Email]
VaTom 10-28-2009 11:25:04 216.12.124.38 250920 Report to Moderator	Re: PTO Driven Generator in reply to RodInNS, 10-28-2009 10:22:25   OK Rod, if you call my industrial planer and chip blower "no load at all"... They remove 3/16" off a 24" oak board in one pass. No idea what your problem was with 45 hp, but something's amiss. You apparently weren't getting much PTO hp. I'm generating 17KW, with a Mitsubishi compact. Yes, running hard- without complaining. Been happy with it for over a decade. The planer's loud enough, the tractor isn't a problem. If I needed 25KW, I'd need a slightly larger tractor. Or a 540 rpm hydraulic motor to run off one of my Cats. Bought one a few years ago, haven't bothered to plumb it. When I need portable power it's usually small enough tools that I can get by with 1000 rpm PTO. A lot closer to that "no load" you were talking about. My PTO generator came already on a trailer, very convenient. There really are a lot of options available. Depends on what one has and how much load. Strikes me as unusual that anyone would always need the maximum 25KW. Maybe you do. Certainly the guy I bought mine from, who was using a 45 hp tractor, didn't. He sold it only because neither he nor his "electrician" could figure out which legs wouldn't blow up his expensive cash registers, even though there was a sign just over the plugs identifying what voltage you get on which plugs, color-coded. A $3 voltmeter would have sufficed. Otherwise, it powered his commercial coolers fine. That load varied a lot. They went to single phase and were happy. As am I.   [Reply]   [No Email]
RodInNS 10-28-2009 15:01:11 216.118.158.123 250935 Report to Moderator	Re: PTO Driven Generator in reply to VaTom, 10-28-2009 11:25:04   We draw the absolute maximum from our 25KVA when we use it. That's 100 amps/250V. We should have a 50 KVA for proper backup to allow normal motor starting instead of having to do sequential starts all the time and shutting half the farm off. When you add up a 4 horse compressor, a pair of 1/2 horse fan motors, 2-1/2 horse pump motor, and various other resistive loads that add up to the 100 amp mark or very close to it. It's often the well pump cutting in that trips the breaker on us if I forget to shut it off. That 25KVA electrical load is equivelant to 37 hp load. If you figuered a drive efficiency of 85%, a fairly typical figure in many drive systems.... That puts you at 43 HP required to drive that 25KVA... so yes, that's pucking my 45 horse pretty hard considering the tractor probably doesn't make quite that power at 540. The 52 HP might, but it's still running at full power. I'm not saying that our generator is highly efficient. It's an 1800 RPM, model MAGNATE MKII made by N.J. Fromnet. Rod   [Reply]   [Send Email]
VaTom 10-28-2009 18:45:53 216.12.124.38 250964 Report to Moderator	Re: PTO Driven Generator in reply to RodInNS, 10-28-2009 15:01:11   Yeah, Rod. I was wondering if there was something less than my Winpower's efficiency with your generator. Not that I think Winpower's necessarily the answer, but this one's working well here with my small tractor. My load is determined by both motor specs and my induction ammeter, which agree. I'm getting 68% of my generator's rated output with 25 hp, which would lead me to expect full power at well under your less-than-successful 45 hp. My Mitsubishi seems to do well at full power, don't know about others. Well, my Cats do the same. I doubt that my 20 yr old Mitsubishi is putting out more than its rated hp. Good little tractors, but far from great. Today I had my hoe attachment on, worked very well. In fact, I recently had the cheap opportunity to keep a Case 580 hoe I sold for a client, didn't take it. My only other uses for PTO are the generator and splitting a couple cords of hardwoods/yr. My compressor's larger than yours, submersible well pump smaller. Mostly, I need to power large 3 phase machinery, like my planer/chip blower. Awhile back I was looking for a considerably larger farm tractor, 80-90 hp. Not for the PTO, but to avoid tearing up my Mitsubishi (again). Then I bumped into industrial loaders, which nobody much values here. Ended up with a 3 yd 4-in-1 bucket Cat which was the answer to my dreams, except for no PTO. Took no time at all for me to forget about a larger farm tractor. As I mentioned, lots of choices out there. Just a matter of selecting the correct one for the individual situation.   [Reply]   [No Email]
Mike M 10-28-2009 18:51:31 72.251.100.24 250967 Report to Moderator	Re: PTO Driven Generator in reply to VaTom, 10-28-2009 18:45:53   Our suposed 18hp JD 750 puts out 24 or 25 on the dyno. So they can be better then rated for.   [Reply]   [No Email]
VaTom 10-29-2009 03:29:03 216.12.124.38 250990 Report to Moderator	Re: PTO Driven Generator in reply to Mike M, 10-28-2009 18:51:31   That's interesting Mike, thank you. We are talking PTO? Yours is a green Yanmar?   [Reply]   [No Email]