hp needed for genny?

[JB4310]

Frank, It's encouraging to hear that you were able to keep things powered up during your extended power outage with your smallest tractor and lower engine rpm (750 pto speed). most home loads are not going to be that huge on average, sounds like we just need to manage the loads with a little simple planning.
I really like the idea of slower engine rpm's for the obvious reasons, lower sound emissions, fuel use and wear. The tractor I'm using is a spare machine not needed for anything else, I'm gonna start looking for a used kub with 2 speed pto in the 20-30 pto hp range to replace it, nothing fancy, don't need 4x4 or loader, just a low hour power plant.
One more thing, my little testing only involved my shop which has a separate service, have not tried powering up the house yet, I'm a little worried about the computer and DLP TV, should I be? I really don't have any big loads in the house except the stove and dryer, so with a little planning I should have no problem staying within that 58-62 Hz window.
I second the notion for a generator forum, maybe make it an alternate energy, inverter, generator forum to make it more useful and since they are all connected.

 

[frankc]

Spot on again Ron! Everything you mention are factors I have weighed during my testing. And boy are you right about that Fan! It moves a tremendous amount of air and I'm sure it is certainly costing me more HP than anyone would initially guess. The L3450 makes an Honest 30HP at the PTO running at 2250RPM on the tack. It is obviously the most stable tractor I have regarding power production. Unfortunately the only other PTO speed available on this tractor is 1000rpm at 2200rpm's. If I throttle it back to 540rpm it's only spinning at 1300+rpms on the tack and this is where that whole inertia thing comes back to bite me. If it had a 750-800rpm PTO setting and would run in the 1800rpm on the tack range, I think I could find a great affordable medium.

One other thing though, when I used the B9200 for those couple of days I was probably running the tractor on average about 10-12hrs out of each day split up across the day in 3-4 hours chunks. Since the hour meter on the tractor only spins a full hour when your running at stated PTO speed, I could run it for about 1hr 20min clock time for every hour registered on the meter. Also, over that 4 days I only went thru between 7-8 gallons of fuel so it was pretty darn economical.

Hopefully all this information is useful to some of the other guys who may be considering PTO gen's or have notions of doing a gear reduction setup and think they will be able to get the comparable amount of power from their sets. Granted, in my case spinning this massive 30Kw head is actually overkill for the smaller machine, but I got a wonderful deal on the generator, SO no complaining from me!

On another note, I have an 8kw ST head that I'm considering mounting directly to a V1105 Kubota engine (approx 15HP at 1800rpms) that I scavenged from a golf course machine. What's stopped me for now is I'm wondering whether the Governor on that engine is going to give me the same NON-results as the Tractors governors. I wonder if Kubota sells a generator governor kit seperately??? Guess I'll have to look into that.

Frank

 

[RonMar]

One more thing, my little testing only involved my shop which has a separate service, have not tried powering up the house yet, I'm a little worried about the computer and DLP TV, should I be? I really don't have any big loads in the house except the stove and dryer, so with a little planning I should have no problem staying within that 58-62 Hz window.
I second the notion for a generator forum, maybe make it an alternate energy, inverter, generator forum to make it more useful and since they are all connected.

If you have a relatively clean power output, you should not have any problem under normal running. Where most run into problem is with a generator with poor waveform shape. Most of the energy is in the peak, so microwaves and switching DC power supplies(most all modern electronics have these) struggle with flat topped or distorted sinewaves. One thing your PTO driven circuitry probably isn't monitoring is over/under voltage. If you should inadvertently run your tractor out of fuel, that large spinning mass will mean a slower spooldown and a longer duration brownout especially if the engine coughs a few times working the last bit of fuel out of it's system. Or if the throttle linkage vibrates loose, your generator may continue to put out power while running way out of specification(low voltage low freq) for quite a while till you can get to it to shut it down or throttle it back up. Brownouts are really hard on electrical devices. 2 things you can do for this are add an over/under protection circuit that cuts power off completely when it goes out of spec, or put all the valuable electronics onto UPSs. This will protect them from excursions away from good power due to generator/tractor malfunction. I have small ones on my entertainment system, my Pellet stove and my computer. A side benefit when on generator power is that if they start beeping, I know there is something I need to investigate.

 

[frankc]

JB, in regard to your questions about HOUSE current, most (90%) of my testing has been done on the house side. Generally, things stay pretty consistent in a house setting, or the power draws are smaller. Excluding obviously things like Air conditioners, Water Heaters, Well Pumps, etc. This is where it does get tricky in my opinion, and really what I've been trying to get across in my threads. The PTO gen produces clean, consistent power but unless you have a tractor that the governor works a bit better than any of mine, any large spike source of power is going to require you to go and manually adjust the rpm's on the machine via the throttle control. Then, when that large surge of power usage is over, you'll be OVER-Throttled and have to adjust it back or risk damaging appliances.

I find this to be true even if I run my Bigger machine that should have no problem producing 12-14KW. Matter of fact, I'm sure it will make that power NO PROBLEM, but I have to adjust it to support that with the load on the machine to keep it safe. I can't just get it all spinning nice with no load and ask it to produce 10KW without having to manually adjust it with the Throttle control. Maybe if I had a 60 HP tractor it would be less noticeable, but most guys on this forum are dealing with 20-40 Hp tractors I would say. Once you start doing the gear reduction stuff, things just get finickier.
Good luck and I'd be glad to help with any other questions.

Frank

 

[JB4310]

JB4310
You made a comment earlier "then once finished heating, idle it down for the lighter loads, even with the big heat load it should stay pretty steady."

You did mean ideling it down by using a multi speed PTO right? There is no ideling it down in traditional AC power generation. You MUST maintain the generator RPM to maintain the 60HZ frequency output. The governor does this by controlling the throttle based on load to maintain engine RPM. So under a low or no load situation, the governor is using just enough throttle to maintain it's set RPM. That is the drawback of an oversized generator. It is setting there humming away at full song burning fuel to move all those engine bits and generator blower with a very light and innefficient electrical load.

Ron, I was actually talking about just adjusting the throttle downward, since his SIL has an all electric house and to heat that if it's a large house it could be 15-20 kw load and and from what I've learned recently that would take some upward adjustment of throttle from no load to keep it at 60Hz, but having the multi speed pto would be even better.

I'll bet that big engine you have is one of those listers, Ive read a lot about them, and thanks for letting us know how much HP those cooling fans can use up.

 

[RonMar]

On another note, I have an 8kw ST head that I'm considering mounting directly to a V1105 Kubota engine (approx 15HP at 1800rpms) that I scavenged from a golf course machine. What's stopped me for now is I'm wondering whether the Governor on that engine is going to give me the same NON-results as the Tractors governors. I wonder if Kubota sells a generator governor kit seperately??? Guess I'll have to look into that.

Frank

That sounds like a good combination. I bet if you connect those two together you will get pretty good results. Remember if it will hold +/- a few hertz you will be fine. It would surely be a better combination for sub 5KW loads than that big old 30KW is. That one portable on the 3PH is the one you use to go rescue the neighbors reefer and freezer every day or so Leting em heat a tank of hot water and take a shower and keep from loosing all their cold food can go a LONG way in neighborhood relations... As for "NON-results", I wouldn't call yours non results, I would call them perfectly predicatble and right on the money for that horse power/genhead/load configuration. And they are also perfectly adequate to power your home when the commercial provider is unable to. I think the 15HP engine and the ST head will be much more efficient combo though.

The Onan 15KW sets I work with use a 30HP 3 cyl bota engine with a selectable governor preset to run at either 50 or 60 HZ. There is also a electro-mechanical followup device to help stabelize it though. Kubota may make a different gov for yours, but I would run yours first on that generator before I worried about a different governor.

 

[RFB]

frankc,

Frank,

I am glad that you posted regarding pto generators. Count me as a vote for a Gen sub-forum. I am in the research stage and I have been looking at Tiger Power for a while. What is your opinion regarding their products and overall service?

My tractor is a Kubota L5030 HSTC producing 43 PTO HP. I am considering the 30Kw Tiger gen for the same reasons the others here have mentioned: increased mass for greater surge.

Our house is all-electric, but I will not need watts for heat since I installed a wood stove with plumbed external combustion air as an emergency heat source. I will use the gen for central A/C and all other household needs.

Along the lines of Ron's suggestion regarding neighborly duties, i was thinking of a carry-all mounted system for portability, but with casters on the bottom to ease storage issues.

 

[JB4310]

This might might reveal how electronically challenged I am but I have to ask, will those surge protector power strips help with the over or under voltages we are talking about here? or are they only for extremes like lightning strikes, I have them for both my entertainment equipment and office.
If not what size UPS is recommended for average computer or entertainment system? I see them on eBay for anywhere from $29. - $7,500. seen a couple of 450 watters for around $100. would that be big enough?

 

[RonMar]

This might might reveal how electronically challenged I am but I have to ask, will those surge protector power strips help with the over or under voltages we are talking about here? or are they only for extremes like lightning strikes, I have them for both my entertainment equipment and office.
If not what size UPS is recommended for average computer or entertainment system? I see them on eBay for anywhere from $29. - $7,500. seen a couple of 450 watters for around $100. would that be big enough?

A surge protector is just that, for surges of several hundred volts, such as from a lightning strike.


As for a UPS, that is where the Killawatt can really come in handy. Plug your entertainment or computer power strip into it and turn on everything you would normally have on, and you will see their combined electrical need. I have a 700Va on my computer, another 700VA on my entertainment system(42" LCD, sat receiver, stereo system and DVD/VCR combo). A rule that has always served me well is to double the routine load for the UPS. So 400VA of load, and I would use around a 700-800VA UPS. This is a little easier on the batterys so they don't get so overheated, and it gives you a little bit of run time before they shut down.

 

[RonMar]

frankc,

Frank,

I am glad that you posted regarding pto generators. Count me as a vote for a Gen sub-forum. I am in the research stage and I have been looking at Tiger Power for a while. What is your opinion regarding their products and overall service?

My tractor is a Kubota L5030 HSTC producing 43 PTO HP. I am considering the 30Kw Tiger gen for the same reasons the others here have mentioned: increased mass for greater surge.

Our house is all-electric, but I will not need watts for heat since I installed a wood stove with plumbed external combustion air as an emergency heat source. I will use the gen for central A/C and all other household needs.

Along the lines of Ron's suggestion regarding neighborly duties, i was thinking of a carry-all mounted system for portability, but with casters on the bottom to ease storage issues.

With your tractor, I wouldn't put any more than a 20KW on it. Any more is just a waste IMO as you don't have the HP to carry much more load than that.

It is quite common to over estimate the ammount of power required when sizeing a backup generator. I think if you do a power study, 20KW will be more than enough, including running a considerable ammount of electric heat. As an example, electric baseboard heaters consume about 250 watts per foot. So 10KW will get you 40 feet of baseboard heater. That is enough for several rooms. I doubt your A/C needs a full 10KW. But with 10KW used, that leaves 10KW for all the rest. HW will pull about 4.5KW(when it is on), oven about the same, electric dryer about 5KW, All the rest of the lights, reefer freezer and well pump probably pull less thean 3KW combined(maybe a little more during startups) but not all these things need to be run at the same time. And remember, it is a backup, so you can probably save a bunch of money in the cost difference between 20 and 30KW and still meet all the necessities and then some. Money that can go into a slick carryall mount and a 100 or so gallon fuel tank so you have some fuel on hand when the worst happens and you can't get any at the local pump cause they don't have power. The inertial difference between a 20 and a 30 is probably not all that great also and certainly not enough to warrant the cost difference when you don't have enough HP to make full use of a 30KW.

My .02