PTO Generator

[RalphVa]

18 hp = 13.2 kw.

Ralph

 

[RalphVa]

I went through the debate with myself a year or so ago and ended up installing a 12.5kw diesel generator from Central Maine Diesel and had an electrician install a new 200 amp panel with auto transfer switch. The generator powers almost everything except the 4 ton heat pump and some other big loads, but it does our little ductless heat pump system in the basement and 2.5 ton heat pump in the upstairs plus well pump, 2 freezers, 2 frigs, virtually all the lights and even our one hot water heater on load management (the clothes dryer and kitchen stovetop are also on load management). It ran last year for 15 minutes every 2 weeks and once for about 4 hours or so in the middle of the night during a power failure. Used 2.5 gallons of diesel for the year.

Cost was about $15k for everything.

Problem with PTO generators is 1) need lots of diesel on hand and constant refueling if out for more than 6 or 8 hours (probably all yours will run on a full tank), 2) you'll need the tractor for snow clearing or clearing downed trees, 3) pain to connect up.

We lived with these problems (excl. #2) with a 4 kw gasoline generator for about 5 or 6 years. It, of course, wouldn't power that much either, but we got by during several power failures and didn't lose any refrigerated or frozen food. 'twas a real pain and safety issue keeping a bunch of gasoline around.

Now, I refuel my tractor from the gen's 60 gallon tank and every so often go and buy some more containers of diesel and pour them back, replenishing and keeping the fuel fresh.

One problem you divert with a PTO generator is how to keep the battery up. On a standby generator, you need a battery tender. Learned this while having the 4 kw one. However, the battery tender went out on the 12.5 kw gen recently and let the battery run down (the gen battery also powers the LED lights and controls on the ATS panel). Do not buy a battery tender that does the voltage conversion at the plug. They fail where the wire gets bent when you close the weather proof box where they're plugged in. I have a weather proof battery tender on it now.

Ralph

 

[Industrial Toys]

My thinking when I considered the PTO genset was that one always has a functioning tractor on hand. No need to worry about all that auxilliary stuff. Batteries, coolant, oil! But it's true, digging the PTO genset out in the dark, disconnecting whatever might be attached to the tractor, because it seems that more often then not, there is usually something on there, is just a royal PITA! At first I had mine on a 3PT skid of sorts. A real pain, and later built a really nice trailer so I could wheel it around by hand.

Although my Onan never gave me a lick of trouble, I was told it was not particularly the Cadilac of gensets. It was not brushless and rotated at a very high speed, being geared up internally.

Don't get me wrong. If I had lots of money, and space to store it, I would have a PTO genset just as backup or to possibly lend out. For if you put your faith in one backup, it will surely fail. I believe in backups for your backups for your backups! Right now, I have the Onan 7.5 Industrial with a Kubota 3 cyl, a 3600 RPM, 3.7 Yanmar, and a 3000 Watt Alpha Commercial Inverter with 48 Volt battery bank.

Unfortunatley my inverter charger does not like the power from the Onan 7.5 and I can't recharge my batteries so the inverter is kind of a one time thing until the batteries are done. I use it mostly at night when I don't need a generator running just to keep the fridge cold.

 

[ruffdog]

Time to put a generator on the wife's exercise bike! It will keep her legs in shape for the summer when she has to pull stumps.

 

[Willie B]

Time to put a generator on the wife's exercise bike! It will keep her legs in shape for the summer when she has to pull stumps.

My friend, a romantic devil bought for his wife's birthday, a new tire for her wheel barrow. They live in a pine forest, where 40 years ago they built a house, removing only enough trees for the footprint of the house. No surprise, the trees now dwarf the house. As a tree dies, he attaches a rope high in the tree, sets up his equipment, and recruits his wife to pull the rope, guiding the direction of fall. He became concerned, she's not as quick as she once was. As a gift with no occasion, he bought her a longer rope. Now she doesn't have as far to run. If that doesn't illustrate true love, nothing does.

 

[ruffdog]

My friend, a romantic devil bought for his wife's birthday, a new tire for her wheel barrow. They live in a pine forest, where 40 years ago they built a house, removing only enough trees for the footprint of the house. No surprise, the trees now dwarf the house. As a tree dies, he attaches a rope high in the tree, sets up his equipment, and recruits his wife to pull the rope, guiding the direction of fall. He became concerned, she's not as quick as she once was. As a gift with no occasion, he bought her a longer rope. Now she doesn't have as far to run. If that doesn't illustrate true love, nothing does.

Ha! Been there and done that!

 

[2Buckslake]

RalphVa pretty much hit it on the head. I work at a company building commercial diesel powered gensets. I too had a PTO generator that I ran off of my NH tractor, until I started building them. PTO generators work best if the load amps are constant, you can set the throttle and not worry too much. However, in a house situation, the loads are ever changing. Most tractor governors are not tight enough to keep that speed constant, as the load changes. If you are running at PTO speed on your tractor, and add a bunch of heavy loads, this will make the rpm's drop because the tractor engine governor is not set up for that demand. If you increase the speed to carry that load, and then the load decreases, it will cause the engine speed on your tractor to increase. That also cause an increase in hertz, well above what it should be. That's why I built a diesel powered 20kw generator with an electronic governor, which will maintain the correct hertz, no matter what the load demand is. I have it hooked thru an automatic transfer switch, which will start the generator when I lose utility power. I live out in the country, and being on a well for water means I have no water in a power outage. So much for living in the country. If you live in the city, an LPG or NG powered generator is a wise choice, if you can stand the cost. Just a few thoughts on my part....

 

[looch]

I've spent some (a lot of) time looking over the various threads on PTO generators, and if I missed it I apologize, but I have a question regarding capacity.

My 3/4 hp jet pump is powered by a 110v circuit. I measured inrush to be around 58A and running to be 11.5A. Obviously, there is some electrical voodoo going on since the pump coming on doesn't trip the 20A breaker - something to do with the impossibility of providing that much power, so the voltage drops - but I know that is a whole topic unto itself.

Let's say, for argument's sake that I have one 110V device that requires 5000 watts.
The generator will be connected to the house via an L14-30 to a manual transfer switch, powering a subset of selected circuits.
The generator has an output of 7200/7800 watts running/surge.

Will it power my single, 110V, 5000 watt (surge, 1500 watts running) circuit? Or, is the 7200 watts only available on 240 with the maximum power for 110 being half of that (3600)?

I suppose it would be advisable to convert that pump to 220 - that would render the question moot, but I'm curious nonetheless.

 

[MikeInEburg]

Most generators use a capacity rating at 240 volts - I would guess that a 7800 surge generator would supply only 3900 watts at 120V. Even if you don't use a generator, you're do well to convert to 240V - especially if your pump will go either way. I'm looking for a 10K PTO generator, simply to avoid virtually the same issue. Mike

 

[Willie B]

During start up of a motor the inrush of current can overload a generator or more accurately a number of components can overload to failure. If start up of motors overloads the engine, it will slow, frequency will fall, voltage will fall. As power is the balance of voltage and current, if the same job is to be done or the same amount of power is used, when voltage falls current rises, as failure proceeds current skyrockets. As current skyrockets, voltage loss in the circuit increases,it all goes exponential! If the breaker doesn't trip soon enough windings or electronic components overheat and melt. It is likely your Kubota will have adequate torque to muscle the motor to start preventing failure.

If load is applied at 240 volts the whole generator winding shares load. loss in circuit is less than half. The motor supplied with adequate voltage, starts quickly with less inrush current. You smile and feel smart for having done the right thing.