PTO Generator - which one to choose

[dourobob]

Hi Folks
I, like many lately, have been exploring the stand-by generator option and I have come up with two possibilities that appear viable for my situation. I have a 200 amp manual pole top transfer switch already professionally installed.

Option One

A 25+ year old WINPOWER PTO Unit with 25 kw peak, 15 kw continuous used as a back up on a dairy farm. There is a Master Dealer not too far away and they recommend a full service for about $850 because of the age of the unit and the possibility of cracked or degrading seals and bearings. Fully serviced and considering travel cost I would have about $2500 invested in what would be a "virtually new" generator.

Option Two

A Generac PTO unit 40kw peak and 20 kw continuous. Age is unknown but seller said it was service about 5 years ago just before he bought at a farm sale. I have not found many positive comments about this brand and have had no success in finding information about available parts and service. For this unit I would have invested between $1400 and $1600 (still negotiating)

I live in Central Ontario, Canada and am leaning toward the Generac unit (closer, about $1000 less expensive and theoretically "ready to go") but would appreciate any comments related to the following questions:

1. Is a Generac PTO unit reliable?
2. Are Generac parts readily available or standard enough to be easily substituted?
3. I have read about having to "flash" the units - is this common, difficult, repairable?
4. Is there a strong reason to walk away from this unit as fast as possible?
5. If I was spend your hard earned money, which unit would you want me to buy and why?

Thanks for any insights.

Bob

 

[brin]

Hi Folks
I, like many lately, have been exploring the stand-by generator option and I have come up with two possibilities that appear viable for my situation. I have a 200 amp manual pole top transfer switch already professionally installed.

Option One

A 25+ year old WINPOWER PTO Unit with 25 kw peak, 15 kw continuous used as a back up on a dairy farm. There is a Master Dealer not too far away and they recommend a full service for about $850 because of the age of the unit and the possibility of cracked or degrading seals and bearings. Fully serviced and considering travel cost I would have about $2500 invested in what would be a "virtually new" generator.

Option Two

A Generac PTO unit 40kw peak and 20 kw continuous. Age is unknown but seller said it was service about 5 years ago just before he bought at a farm sale. I have not found many positive comments about this brand and have had no success in finding information about available parts and service. For this unit I would have invested between $1400 and $1600 (still negotiating)

I live in Central Ontario, Canada and am leaning toward the Generac unit (closer, about $1000 less expensive and theoretically "ready to go") but would appreciate any comments related to the following questions:

1. Is a Generac PTO unit reliable?
2. Are Generac parts readily available or standard enough to be easily substituted?
3. I have read about having to "flash" the units - is this common, difficult, repairable?
4. Is there a strong reason to walk away from this unit as fast as possible?
5. If I was spend your hard earned money, which unit would you want me to buy and why?

Thanks for any insights.

Bob

Bob,

I bought a Generac PTO Generator...Model No. 6870 ~ It is 20KW continuous and a 40KW surge...sounds like it is the same unit you are looking at..I bought it used from a Chicken Farmers widow...she said it had been used only a few times over the years...but who knows...I bought it 3 yrs. ago for $250.00...it came with the 3 pt. stand and PTO drive-shaft and works great.

You can call Mr. Moe Moeller 812-824-4434 ...he has all of the spare parts for the generator and can give you any information or answer any questions you might have...When I spoke with him he was easy to talk to and happy to answer my questions...

As far as any gaskets leaking...you can simply use John Deere cornhead grease or 00 grease instead of the gear oil...I have done that and had no problems. I also checked with 2 generator repair facilities close to my home and they both can service this generator...So I would suggest you call around your area and find a generator re builder or repair facility and see if they work on that model... then you will feel better.

 

[5030]

Years ago, I had a Winco 15KW unit that I sold because it was basically an impossibility for my wife to hook it up if I wasn't home plus you'll need a transfer switch or a hefty double pole single throw switch to isolate the utility from your system.

I went to a Generac standby 17KW propane fueled unit (8 years ago) because it's turn key for the wife.

If I was buying a portable unit (Winco/Generac), I'd lean toward the Winco, not that the Generac isn't a good unit because in 8 years, I've had little problems with my standby and it's Generac.

You'll need a mount for either (3point frame or trailer, upspeed gearbox (( the head needs to turn 3600 rpm from 540 pto)), pro shaft and of course, some type of disconnect).

You also need to be aware that the genny needs to turn 3600 (2 pole head) so the tractor will be at 540, 24-7, or as long as you require power. I say that because it's possible to back off the rpm input, but your cycles per second (Hz) will also decrease (as the Hz is a direct result of the armature speed of the genny) and less than 60 Hz can be detrimental to electronics, cause clocks to lose time and cause motors to overheat. like your refrigerator for instance.

Holding the tractor at 540 for hours on end, or days, will eat fuel plus you'll have to shut down the tractor for maintenance, and fueling. The more amperage you pull, the harder the genny pulls against the tractor drive and your load will vary so the pto speed will vary (and the cycles per second produced). A standby has throttle compensation, your tractor has you to modulate the throttle to maintain 60 Hz, another drawback.

It was less intensive for me to go standby/stand alone genny, so I sold the Winco.

Full fielding 'flashing' the genny isn't hard. What happens is, over time, the armature loses it's residual magnetism. It's that slight magnetism that 'excites' the field windings and causes the initial flow of electrons that initiates the process of generation. Standby units do that automatically.

If your power needs are non-critical and you don't mind hooking up the genny to the tractor in sub zero, snowy weather or during a summer windstorm, because power tends to only fail when the weather is adverse, the get the pto unit. For me, I prefer not to.

Finally, don't expect to run your sensitive electronics (like your computer) on fluctuating power from a pto unit. Sensitive electronics are just that. They may or may not operate but the overall life will be shortened no matter.

Just some points to ponder.

 

[brin]

Just to add....I run my tractor a 540 RPM for hours on end bush hogging...and it does not harm my tractor...that is what tractors were made for.

I don't run my generator 24/7 ...during an outage...I run it long enough to warm or cool the house, keep the frig. cold, flush toilets , take showers etc. It is just a waste of fuel to run it 24 / 7

So far our generator has not hurt our computers, appliances , Plasma TVs or anything else in our house..

The throttle on my tractor can easily be set to maintain a steady 540 RPM

It takes only 10 minutes to hook up the PTO generator ..in the barn before connecting it to the hose plug and that takes 2 more minutes.

The Generac PTO genny I have and the OP is talking about ...the head turns at 1800 rpm from 540 PTO.

Just wanted to add my experience with the same unit the OP is asking about.

Good Luck !

 

[5030]

Just to add....I run my tractor a 540 RPM for hours on end bush hogging...and it does not harm my tractor...that is what tractors were made for.

I don't run my generator 24/7 ...during an outage...I run it long enough to warm or cool the house, keep the frig. cold, flush toilets , take showers etc. It is just a waste of fuel to run it 24 / 7

So far our generator has not hurt our computers, appliances , Plasma TVs or anything else in our house..

The throttle on my tractor can easily be set to maintain a steady 540 RPM

It takes only 10 minutes to hook up the PTO generator ..in the barn before connecting it to the hose plug and that takes 2 more minutes.

The Generac PTO genny I have and the OP is talking about ...the head turns at 1800 rpm from 540 PTO.

Just wanted to add my experience with the same unit the OP is asking about.

Good Luck !

Experiences differ. I'm probably a lot older than you and I don't relish hands on operation anymore.

I guess if intermittent power is fine in your house/operation, that works, It's not fine here, consequently, I need and require a constant source of on demand generation.

Far as maintaining 540 input, I suggest you set your genny up and set the throttle/pto for 540 and then load the genny. The report back on what occurs. Your comment about maintaining constant input speed under no-load to load parameters is false. Go try it and then let us know. Postulation is wonderful, real time experience is priceless.

Your power source (tractor or whatever) isn't capable of compensation for load unless it's direct coupled electronically and/or mechanically to the generator head and can sense the applied load. That's how it works.

 

[brin]

I typed what I typed from experience with my PTO genny under load and when the well pump or heat pump kicks on , there is a momentary blip and that is it...The generator I have and the one the OP is discussing has a 40KW surge capacity and therefore when a motor kicks on it compensates nicely...I don't have to report back to you about anything...especially when you post that what I am saying is false...Not a very nice thing to do..Imagine what you are doing....I have owned and operated my generator for 3 yrs. and you are telling me what my tractor is capable of and what I am posting is false...Wow !

 

[dourobob]

Bob,

I bought a Generac PTO Generator...Model No. 6870 ~ It is 20KW continuous and a 40KW surge...sounds like it is the same unit you are looking at..
You can call Mr. Moe Moeller 812-824-4434 ...he has all of the spare parts for the generator
As far as any gaskets leaking...you can simply use John Deere cornhead grease or 00 grease instead of the gear oil...I have done that and had no problems. I also checked with 2 generator repair facilities close to my home and they both can service this generator...So I would suggest you call around your area and find a generator re builder or repair facility and see if they work on that model... then you will feel better.

Excellent points - thanks for comments from first-hand experience.

Hope to speak with a couple of local genny repair shops tomorrow (not open today - Sunday) and then decide.

Bob

 

[JB4310]

I wish these tractors especially the new ones with all the electronics could have an option to regulate constant PTO speed electronicly.

Because in my hands on experiments with my IMD 10 kw pto genny, the tractor's mechanical governor could not compensate for going from no load to full load, any wide fluctuation in load could not be compensated for and the HZ would be way off. So from my experience PTO gennys are not plug and play friendly. They are the cheapest way to get the most amount of KWs provided you own a tractor, but they are not set and forget.

Which for now is ok with me, I will treat a power outage as a major event and will be running around like the crew in a ships boiler room keeping things running. And will be producing electric power in a conservative manor, maybe a couple hours on and several hours off.

Now the newer AVR models should be better, mine is capacitor regulated as I imagine the used ones OP is referring to, are as well.

JB

 

[Mickey_Fx]

No dog in this fight but do have a few opinions.

Gov's on a tractor are not optimized for generator service but some handle the chore quite well. I'd try and set engine speed with moderate load so it is running at intended freq. Hopefully, gov can hold speed to within a couple hertz as load changes.

As for gen speed, wonder how many of these larger size gens being discussed are 2 pole, i.e. 3600 rpm? Personally I wouldn't have a larger genset that wasn't 4-pole.

Sensitive electronics as mentioned, non-issue. most all electronic today us a switching power supply. Can handle broad range of input voltages and 50/60 hz. I'd be more concerned over things with induction motors as they don't handle being run at wrong freq very well. Creates a lot of excess heat. I wouldn't worry about being off a couple hz but would start to worry if running 10 hz off and trying to be run for extensive periods of time.

 

[RickB]

Experiences differ. I'm probably a lot older than you and I don't relish hands on operation anymore.

I guess if intermittent power is fine in your house/operation, that works, It's not fine here, consequently, I need and require a constant source of on demand generation.

Far as maintaining 540 input, I suggest you set your genny up and set the throttle/pto for 540 and then load the genny. The report back on what occurs. Your comment about maintaining constant input speed under no-load to load parameters is false. Go try it and then let us know. Postulation is wonderful, real time experience is priceless.

.

Your "real time experience" seems to vary from mine. I have been using PTO powered gensets for backup power in residential and agricultural uses for at least 35 years.
There is a device within a tractor's injection pump called a governor. It controls fuel delivery based on the load placed on the tractor's engine and is designed to maintain the pre-set ERPM setting within the engine's ability to meet the torque loading demand asked of it. Governors have been an integral part of modern diesel fuel injection systems for probably 70 years or more. They also work well enough to maintain voltage/Hz outputs on PTO gensets when the genset and tractor powering it are sized for the expected load. PTO generators (like mine) can be an inconvenience, and many folks choose a more automatic, hands off solution to emergency power. But the concept has been successful for decades and is still a viable alternative.

 

[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