PTO Generator - which one to choose

[90cummins]

I have a Ford 1720 and a Generac PTO-25 25kw continuous 50kw surge.
My experience with my tractor is if I set it at 61~62hz no load it will handle my entire house including the electric dryer 5.5kw, deep well pump and any other load up to 8~10 KW without dropping below 58~59hz.
Not all tractors or gensets including identical units will handle the load the same. Some have very accurate speed control where others will vary quite a lot.
I have also seen this first hand with my 2 identical Generac 4kw portables. One will vary 4~6 HZ zero to full load and the other will maintain +-1HZ. I attempted to correct the Generac with (poor control) based on operation of the other but could not determine why it was different.
Having worked in engineering I have seen many, many times where everything is the same but one is always different!
As far as which one to buy my Generac is a very well built (heavy) 4 pole 1800 rpm unit that has AVR voltage regulation which maintains voltage regardless of speed (HZ) fluctuations and 50kw surge providing there is enough HP available. It also has a HZ and voltage meter facing the tractor making it easy to set the proper engine speed.
I would also like to say I wish my tractor had a 2 or 3 speed PTO so I could run my engine at reduced rpms during times of low HP requirements.
Tim

 

[dourobob]

A quick update - feedback from two sources locally (my master electrician who specializes in farm installations and also the most highly respected genny repair shop in Ontario - Sommers in Tavistock) steered me away from Generac. Parts availability and operating reliability where the two major downfalls in this area.

Did a deal on the 25/15 Winpower unit - hope to have everything in pace in a few weeks.

Thanks to those who provided the helpful comments.

Bob

 

[HAR]

dourobob:
I do not think you can go wrong with the Winpower unit. Winco/Winpower have been a cornerstone for farm and other standby power for years. They are a well known and reputable company who stand by their product. I think that almost every electrician/repair shop has handled and worked with Winco/Winpower for years. I have a neighbor who has a nearly 30 year old Winpower unit that is still going strong as backup power to his farm/sawmill. His was one of the reasons I purchased mine in 2003. Enjoy!

 

[RonMar]

Generator governors have FULL throttle authority. IE, thay have control of all the engines available HP. Tractor governors do not have full throttle authority. They only hold sway over a small ammount of the tractors total available power. The people who have the best success with PTO generators are the ones with the larger tractors I think, as their governors have a larger available HP range. All mechanical governors have RPM droop. You must have an RPM decrease to provide the motion to increase the throttle. Knowing those 2 things, PTO generator setup should be as follows: If you ask your utility, I do not think they will claim anything better than +/- 5%, although it is typically much better than that. So set your generator RPM, with no electrical load, to deliver approximatly 63HZ. That way if the electrical load suddenly drops, the frequency should never really exceed this point. Then apply the load and let the frequency droop toward 60HZ. Keep applying electrical loads untill the frequency droops to 57HZ. Total up the electrical loads and that is your maximum capacity on the PTO generator that your governor can deal with. Live within that limit. I have a generator with a mechanical governor. I set it for 62HZ and it droops to 58HZ when at maximum load.

Can't measure frequency? go buy a 'kill a watt". It is a device to measure electrical usage of appliances. It plugs into the wall and an appliance plugs into it to measure it's usage. It also displays voltage and frequency on the line at any outlet it is connected to. About $29... No person contemplating generating their own power should be without one. With the killawatt in my living room set to frequency, I can tell at a glance the electrical load on my generator...

 

[Soundguy]

northern units in the 13-25K are in the price ranges you mention.

I have a 13k and my stepdad hs a 25K.. both work great.

soundguy

 

[Soundguy]

The people who have the best success with PTO generators are the ones with the larger tractors I think, as their governors have a larger available HP range. ...

it does help for sure.

my 13kw genny realistically wants a 24 or so hp tractor to realize full output. i have plenty of times ran it on my 67 pto hp ford 5000, or ~90 pto hp NH 7610s, and i can tell you that you can go from 0 load to 10kw instantly and no sound changes in the engine and no freq change.. something about having 3-4x the power needed.. plus the large rotating mass / flywheel effect that surely helps.

contract that with an old 27hp gasser and a 6kw load kicks on and you hear the governor rip for a second to hold it..

soundguy

 

[tsteahr]

The people who have the best success with PTO generators are the ones with the larger tractors I think, as their governors have a larger available HP range.

I have had excellent success driving a 10KW PTO with 19 pto hp rated scut. I suspect the actual pto power is slightly higher as the tractor has no problem driving the generator to full output, to the point of tripping the 40amp 240V breaker on the generator.

I set the frequency at 60.5Hz no load. Frequency drops to 59.5Hz at full load. Obviously I have been very pleased with the performance of the tractor's governor.

Speed control was my major concern prior to buying a PTO unit. Now that I have over 100hrs driving the pto generator with the tractor, I have full confidence in the setup.

 

[RonMar]

I have had excellent success driving a 10KW PTO with 19 pto hp rated scut. I suspect the actual pto power is slightly higher as the tractor has no problem driving the generator to full output, to the point of tripping the 40amp 240V breaker on the generator.

I set the frequency at 60.5Hz no load. Frequency drops to 59.5Hz at full load. Obviously I have been very pleased with the performance of the tractor's governor.

Speed control was my major concern prior to buying a PTO unit. Now that I have over 100hrs driving the pto generator with the tractor, I have full confidence in the setup.

1HZ of frequency droop over 10KW of electrical load on a mechanical tractor governor is nothing short of amazing! What tractor make and model are you running?

 

[JB4310]

1HZ of frequency droop over 10KW of electrical load on a mechanical tractor governor is nothing short of amazing! What tractor make and model are you running?

Must be AVR. If AVR regulates the voltage then it must help keep the HZ in line as well ???

My 10 kw is capacitor regulated and I have to manually adjust throttle to stay within spec during large load changes.

I wonder how big a difference the avr makes and how much it can compensate for??

JB

 

[Soundguy]

1HZ of frequency droop over 10KW of electrical load on a mechanical tractor governor is nothing short of amazing! What tractor make and model are you running?

I'm getting the same. did it on a ford 5000 and NH 7610s using a northstar 12.5kw rated pto genset.

mind you.. the tractors in question are capable of 67 and 90 pto hp, and the genny wants 24 pto hp.. so ther eis plenty of rotational mass in the tractor to keep a load going at startup.

soundguy