PTO generator selection help

[workinonit]

Is either of them a 4 pole or are they both 2 pole units.
I believe the 4 pole will provide cleaner power with better recovery.

It's not the first time I've heard this and having worked in thee business for 40 years I would like to know the basis for this. My understanding is that the difference in generator poles is simply related to the desired speed for the turbine that is spinning the generator. I know that I work on voltage regulators on cross compound units that have both a 2 pole and a 4 pole generator on a single turbine, all related to the desired speed. Be it 1800 or 3600 RPM. But in all my years I've never heard that the 4 pole has cleaner power or recovery time.

 

[LouNY]

OK, here is my line of thinking and what I have observed over many years and quite a few farm pto generators. The 2 pole units did not see as smooth running and had more trouble with load regulation and recovery from surge loads.
Much of the recovery does have to do with the tractor providing the power and how responsive it's governor is.
In that same vein and for ease of numbers;
if a tractor has a pto speed of 540 at 1800 engine rpm,
the generator gear box has to up that rpm to either 1800 or 3600 rpm.
If a load change results in a 20 rpm change in tractor engine speed that would be twice the frequency change in the 2 pole compared to the 4 pole.
The 2 pole units seemed to have a harder time staying at frequency compared to the 4 pole units. People that had electrical problems when on generators it seemed like the 2 pole had more issues then the 4 pole. The tractors seemed to run steadier with less seeking from the governors.
I don't know for sure if it was a 2 pole 4 pole issue or a rotating mass issue, also I much prefer 1800 rpm over 3600 rpm for a driven or driver.

 

[ponytug]

It's not the first time I've heard this and having worked in thee business for 40 years I would like to know the basis for this. My understanding is that the difference in generator poles is simply related to the desired speed for the turbine that is spinning the generator. I know that I work on voltage regulators on cross compound units that have both a 2 pole and a 4 pole generator on a single turbine, all related to the desired speed. Be it 1800 or 3600 RPM. But in all my years I've never heard that the 4 pole has cleaner power or recovery time.

Count me in on hearing a good explanation as well. It makes no sense in theory, at least as far as I know.

I wonder if, to the extent it isn't an urban myth, the purported low power quality arises out of two pole 3600 rpm generators often being designed for an inexpensive price point, and the reportedly lower power quality being a reflection of the corners being cut on the voltage regulators, winding specifications, governor design, etc. Or perhaps leftover from earlier days when brushed generators were more common.

All I know is that the 2 pole generators that I have checked have had pretty good power, albeit a few of them did need adjustment in one way or another. Then again, none of them were "super cheap".

All the best,

Peter

 

[Hughman]

I haven't found any 4 pole generators in the 15kw size range so that might not be an issue for my selection.

Other issues I'm considering is capacitor vs avr and trailer vs 3 point platform.

 

[RjCorazza]

I haven't found any 4 pole generators in the 15kw size range so that might not be an issue for my selection.

Other issues I'm considering is capacitor vs avr and trailer vs 3 point platform.

I like my Winco 15kw. It's capacitor regulated, as you are aware. I haven't had any issues with sensitive electronics.
Something in the back of my mind from my portable Generac days was that AVR units had a higher surge rating, but I may be recalling incorrectly. The Generac 7kw had a large 12kw surge rating.
I elected to go with the trailer mount so I could wheel it out of my small shed then hook it up outside, rather than have to store a 3 point mount where the tractor could back up to it. It's pretty easy to move it around by hand.
Anyway, I chose Winco more for the company reputation.

 

[LouNY]

I like AVR but it is something that can go bad.
My preference is for a trailer. In my mind there are a couple of reasons.
A trailer can be towed any any vehicle, handy in my mind.
A trailer mount can be left unhooked and just back up and connect the pto shaft to use.
To me it is easier to connect the pto on a trailer then having to crawl around the the lift arms on a 3 point.

 

[workinonit]

Count me in on hearing a good explanation as well. It makes no sense in theory, at least as far as I know.

I wonder if, to the extent it isn't an urban myth, the purported low power quality arises out of two pole 3600 rpm generators often being designed for an inexpensive price point, and the reportedly lower power quality being a reflection of the corners being cut on the voltage regulators, winding specifications, governor design, etc. Or perhaps leftover from earlier days when brushed generators were more common.

All I know is that the 2 pole generators that I have checked have had pretty good power, albeit a few of them did need adjustment in one way or another. Then again, none of them were "super cheap".

All the best,

Peter

You guys are hung up on these small units we hook up to our homes. In fact, if 2 pole generator power was suspect they would be installed in the majority of the power plant generators in the US. About the only 4 pole un its that I know of are the nukes and a few cross compound units that run a 2 pole and a 4 pole together. Hydros can range from 4 pole to 40 pole depending on how fast the water wheel can turn the turbine/gen. All of them have clean power.

 

[LouNY]

You guys are hung up on these small units we hook up to our homes. In fact, if 2 pole generator power was suspect they would be installed in the majority of the power plant generators in the US. About the only 4 pole un its that I know of are the nukes and a few cross compound units that run a 2 pole and a 4 pole together. Hydros can range from 4 pole to 40 pole depending on how fast the water wheel can turn the turbine/gen. All of them have clean power.

I don't know what industrial applications you are working with, the "hi speed" units used to be primarily direct coupled 4 pole 1800 rpm or even 6 pole 1200 rpm gensets.
The older natural gas piston generators were often 8 pole at 900 rpm or 10 poles at 600 rpm,
occasionally even a 12 pole at 600 rpm direct driven by a large straight 8 engine that you could stand in the crankcase to rebabbit and scrape the bearings.
Even the high speed turbines running upwards to 30,000 rpm had multiple stages of planetary gearsets to drop down and run a 6 or 8 pole generator.

 

[workinonit]

I work in or have worked in pretty much all the power plants in the US from nuclear to 2 MW hydro units and literally everything in between. There are probably less than 200 4 pole generators in the US that are over 50 MW and it's been that way for a long time. The lion share of the power grid is supplied by 2 pole, 3600 RPM machines that are coal fired, natural gas fired or oil fired. I do work on some hydro units that can get up to 40 pole machines. I have just started getting into retrofit AVRs on some of the small gas turbines but we don't usually fool with any units under 35 MWs or so.

 

[90cummins]

I bought a 25kw continuous 50kw surge 1800 rpm Generac PTO unit in 1999 in preparation for Y2K which never happened.
After reading this post I need to ask if there is a real advantage of 1800 rpm versus a 3600 rpm PTO generator?
90cummins