PTO Generator inadequate for larger HP motors?

[Marslander51]

I was looking at Baumalight's site at the TX12 specifically, and it had a warning in the manual to not use for over 2HP motors or the generator could be damaged. I emailed Baumalight and they confirmed, none of the TX series are rated for more than 2HP regardless of watts, and they recommend the 4 pole KR or QC series. I have a 3HP well pump and need something to power it.

If Baumalight says this, do other manufacturers - Winco, Northstar, IMD, HF- have a similar requirement? I have looked at some of them but have never come across this type of warning.

For those with PTO generators, do you run motors larger than 2 HP and if so, are there any problems or issues?

Is your pump starting under a full loads? You could measure the amp draw when starting with head pressure and without. If the unloaded start is within the capacity of your generator, I would think you’d be ok if you can start the pump with an open head and then build pressure after it’s running.

 

[hummertom]

Much more efficient to get a small diesel generator than to tie up your tractor. Running a 32hp tractor to run a 3hp pump doesn't make any sense to this old electrician. A 10kw genset will produce about 45amps at 120/240 vac. Or get a propane one, much better in cold weather and quieter. I run my 2100 sq ft house (except AC and dryer) on a 10kw propane genset, during prolonged outages I shut it down at night to conserve fuel (think PGE in NorCal) 2 years ago we went for 2 weeks on 150 gals of propane running 12-14 hrs a day.

 

[qualsite]

With any of your options, do not attach or start up your generator with a motor load on it... make sure the well is OFF until your generator is up to full speed, and you aren't getting voltage drop by using too-small a cable from the generator. I run my 3HP well pump all the time with my 13HP 6500W Generac generator, and it works fine. It does depend upon how beefy your generator is for the startup surge of the motor, and many cheaper lightweight generators will give you the load watts, but not the startup surge, because they don't have enough magnetic mass [iron] built into them to handle the instantaneous load and they magnetically saturate and shut down [or burn up if not well protected]. Also, not all HP startup loads are the same, and a well pump is usually an easy-load short-duration startup, and the start capacitor takes most of that and shuts off in less than a second. That being said, the instantaneous start load is still about 70 lock rotor amps, before it immediately drops down to about 12A @240V running load. Look for a physically heavy generator that will handle the instantaneous loading for the HP/application you want to start... and says so in the specifications.

 

[RBsingl]

For a number of years I ran the well pump with a 7.5KW portable gas generator. It worked but was a pain. I would shut off all the other stuff when I needed the well pump to run. It was also no fun moving the generator and setting it up when power went out, usually late at night during a snowstorm. I did add a second large pressure tank to provide around 45 gallons of drawdown between pump cycles which made the small gas generator less troublesome.

A few years ago, I installed a 40KW standby generator powered by a 3.3L Mitsu turbo-diesel and switching is handled by a 200 amp commercial grade auto transfer switch. When the power fails, the generator starts and goes into a 4 minute warm up cycle before transferring which provides time for the engine to warm up and for any compressor operated items to equalize rather than restart under load. When commercial power returns, it starts a 3 minute timer to ensure it is reliably staying on and then does an in phase transfer and the generator goes into a 4 minute cooldown cycle. MUCH more convenient than dealing with the prior setup!

 

[Ghostdance56]

I was involved with adding a transfer switch at a dairy operation. After the switch was installed the farmer brought over the PTO driven generator on a pallet carried by the 3 point hitch of a 60+ horse power tractor. The farmer connected power lines from the generator to the switch. He ramped up tractor rpms turning the generator. When the switch was thrown to put dairy barn load on the generator, the generator itself started turning with PTO shaft! The tractor beat the generator to pieces in a matter of milliseconds!! The generator wasn't anchored solidly enough to stabilize it when load was added!

 

[hummertom]

In order to connect to house, best to use manual or automatic transfer switch.

 

[crlf]

With apologies for not reading the whole thread and thus for potential duplication of verbiage.. but if this is to power a static application that's wired to the building, and if other parameters are in line, a more comprehensive and flexible solution may be desired, e.g.:

Sol-Ark 15K All-In-One - Sol-Ark

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With this type of controller, you land the service entrance on it; its output feeds the main panel; add a 48V battery bank to taste, solar panels optional (but it'll handle a very large array). It's stackable, allowing for scaling up to larger applications.

The controller has a dedicated generator input which you can then feed with a smaller generator if the battery bank starts to deplete, with no inrush issues on the generator.

 

[HAR]

FWIW:

I do not know if this will help anyone or not, but here goes.

I have had a Winco PTO genset since 2003. When I purchased it, I remembered there being a discrepancy between what I ordered and what I was shipped. At the time I was told by the sales rep that they did not have the smaller generator head in stock, so they were going to ship me the next size up. I had ordered a 7Kw unit (W7PTOS /A) and they shipped me a 10Kw unit (W11PTOS /A).

In December 2022, we had another extended outage, and it got me to thinking about my generator setup. In Dec 2022, I contacted Winco to verify what I had. They told me to send them photos of both the Winco data plate and also the generator data plate. I sent them a photo of my 'model number plate' for the Winco genset and also the 'model number plate' from the Leroy-Somer generator head. One of their technical support team replied. And this is what they said:

"Per the data plate you sent in, yes you can expect 10 kW from this unit. (42 amps continuous rating x 240 volts = 10,080 Watts.)

Surge rating on that unit is 14,000 Watts. (roughly 58 amps.) You will likely need at least 20 hp at the PTO shaft output at 540 rpm to be able to fully load your generator.

Thank you,
Daniel xxxxx
Product Technical Support

Attached are the two plate photos associated with the generator. Also included are two technical images.

One of them seems to suggest that my Winco generator is capable of starting a 2-4-6HP motor, if I had at least 20 PTO HP.

 

[Chewwy]

Is your pump starting under a full loads? You could measure the amp draw when starting with head pressure and without. If the unloaded start is within the capacity of your generator, I would think you’d be ok if you can start the pump with an open head and then build pressure after it’s running.

A centrifugal pump starting with no flow path is doing much less work than a pump with an open discharge and pumping fluid. It is only turning the pumps rotating mass and cavitating the fluid at the impeller due to no flow path.

Depending on the pumps design, some minimum flow may be required to prevent pump damage. Although some work is being accomplished with minimum flow, it is still much less than when pumping at rated flow.

 

[TomS2]

My 15kw Winco pto generator starts my 5hp compressor, no problem at all, and it pulls 24.5 amps on 220V, so the start load must be pretty good.

SR

How do you like the Winco? I’m so tempted to purchase one to run the house. Does it keep a pretty constant voltage? Thanks!