ROUSTABOUT
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PTO Generator
- Thread starter WRX
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rScotty
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I might run the tractor for a generator too if our power outages were due to storms. But the last several have been due to forest fires and before that floods. So we need the big tractor free to be used. That's why we keep a hundred HP tractor fueled and ready to use.
On 510 vs 540 RPM question.... Voltage output goes down in proportional to the square of the decrease in RPM. That's reasonable for resistance heaters and not so good for computers, lights or TV.
The drop in frequency is less than the drop in voltage. Frequency is just a regular linear thing. i.e. drop the RPM in half and the frequency drops in half as well. But the problem is that it is the 60 cycle frequency is important to keep constant for some computer circuits. And nowadays even the coffee pot has a computer chip.
Best to just run it at the rated speed if you can.
rScotty
On 510 vs 540 RPM question.... Voltage output goes down in proportional to the square of the decrease in RPM. That's reasonable for resistance heaters and not so good for computers, lights or TV.
The drop in frequency is less than the drop in voltage. Frequency is just a regular linear thing. i.e. drop the RPM in half and the frequency drops in half as well. But the problem is that it is the 60 cycle frequency is important to keep constant for some computer circuits. And nowadays even the coffee pot has a computer chip.
Best to just run it at the rated speed if you can.
rScotty
orezok
Elite Member
Actually, at the advertised RPM it produces the correct frequency (60 cycle). The voltage is secondary.
rScotty
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If it's a self-energized field coil type of generator it can't maintain both voltage and frequency at a lower RPM. It has to choose one or the other. .
Simpler to just run it at rated RPM.
Robin Veerman
Veteran Member
I understand the comments above. But I was wondering why most generators are 540 rpm while some others are 510 rpm. I’m thinking that the main benefit is better fuel economy with a 510 unit…
rScotty
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I've wondered the same thing. A generator can be built to operate at any RPM. And then if it's run at any other RPM we know what the trade-offs are. But why 540 rpm for PTOs anyway?I understand the comments above. But I was wondering why most generators are 540 rpm while some others are 510 rpm. I’m thinking that the main benefit is better fuel economy with a 510 unit…
Does anyone know why 540 rpm became standard for PTOs in the first place? It seems an unusual number...
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Bill Guenthner
Platinum Member
When the power is out (very seldom) I can get by with a Honda portable gen and it gives good clean power that won’t heck up my TV and computers, and sips fuel in economy mode. And the Honda gen can go camping, tailgating, RV’ing. The other benefit is that the tractor is free to push snow or tree limbs or do other chores, and I don’t want to put 24, 48 or 72 hours on the tractor meter just to keep lights on and the refrigerator running.
Robin Veerman
Veteran Member
From google…. 540 was the early standard primarily because it was the speed of the intermediate shaft in the Ford 9N, 2N, and 8N transmission at the engine speed for near maximum engine power. That PTO was very simple inside the tractor, and is just an extension of the transmission intermediate shaft.
sea2summit
Elite Member
I would imagine it's because 540 has been the standard for most small/midsize tractors since...forever? 510 may be a way to get some fuel efficiencies as some tractors have more than enough PTO HP to run a generator so the power band at 510 is sufficient to generate the required kw(s)? Pure guess on my part. If I was trying to generate 10 KW for my house that's ~14 HP so waste a lot running my MX with ~50 PTO HP at 540 RPM, probably be more efficient to run my larger tractor at 540e and much more to run the larger 540e at 510 I bet while still generating plenty of PTO HP. Assuming as mentioned all the output specs still work.
ETA you're probably not running a standard 540 at exactly 540 on your tractor's TACH either if you're measuring the output of the generator, probably close but you should be measuring the output from the generator not the tractor PTO RPM.
orezok
Elite Member
Your basic 2 pole generator needs to turn at 3600 RPM to produce 60 cycle power. To get from 540 or 510 to 3600 just requires different internal gears to obtain the required RPM. Maybe one set of gears is cheaper than the other. Who knows..I understand the comments above. But I was wondering why most generators are 540 rpm while some others are 510 rpm. I’m thinking that the main benefit is better fuel economy with a 510 unit…