Question for all the engineer types
08-09-2010, 09:02 PM
#1
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Thread Starter
Question for all the engineer types
I have a 10HP diesel engine that I want to use to drive a 12000 watt generator. I know that 12000 watt generators usually demand at least 16 HP, but the generator I want to get is an 1800RPM unit. The engine runs at 3600RPM. If I used a 4" pulley on the engine and a 8" pulley on the generator, could I use the 10HP engine?
In my way of thinking, I have halved the RPM's by using the pulleys, making the generator run at its' 1800RPM's while the engine runs at its' 3600RPM's. Also, I think I should have halved the HP requirement of the generator as well, haven't I?
In my way of thinking, I have halved the RPM's by using the pulleys, making the generator run at its' 1800RPM's while the engine runs at its' 3600RPM's. Also, I think I should have halved the HP requirement of the generator as well, haven't I?
08-09-2010, 09:10 PM
#3
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08-09-2010, 09:18 PM
#4
Banned
Continued reduction in speed does not multiple the horse power made nor reduce the horsepower demand. As energy is not lost or created as it changes.
You can run the engine all day long with any combination of pulleys and you will only be able to make at best 7.45 kw. As a matter of fact you will have friction loss in the belts and will more then likely be closer to 7.0 kw when it is said and done. You will have changed the torque curve with your pulleys but not the horsepower.
You can run the engine all day long with any combination of pulleys and you will only be able to make at best 7.45 kw. As a matter of fact you will have friction loss in the belts and will more then likely be closer to 7.0 kw when it is said and done. You will have changed the torque curve with your pulleys but not the horsepower.
08-09-2010, 09:20 PM
#5
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actually, while belts are very efficient, you looking at up to 10% power loss on top of that...
next question, how realistic is your 2500 watt requirement?
next question, how realistic is your 2500 watt requirement?
08-09-2010, 09:22 PM
#6
With age comes the cage
Just put that new liberty of your on blocks and run leather belt around around a rim with no tire on it.. Set the cruise control to provide you with the rpm needed to keep the gen set a hummin.. there wasn't that easy! 
Keep in mind when dealing with a true gen set and not an inverter your stator RPM is what gives you your 60 Hz frequency.. your 10 hp (running at 3600 rpm) might work for half load but anything more will slow down the engine / gen-set and fry your electronics..
Keep in mind when dealing with a true gen set and not an inverter your stator RPM is what gives you your 60 Hz frequency.. your 10 hp (running at 3600 rpm) might work for half load but anything more will slow down the engine / gen-set and fry your electronics..
08-09-2010, 09:24 PM
#7
Banned
T = (HP x 5252)/N
T = Torque (LbFt)
HP = Horsepower
N = Speed (rpm)
But you also have to consider the pulleys
T = F x R
T = Torque (LbFt)
F = Force (Lbs)
R = Radius (Ft)
T = Torque (LbFt)
HP = Horsepower
N = Speed (rpm)
But you also have to consider the pulleys
T = F x R
T = Torque (LbFt)
F = Force (Lbs)
R = Radius (Ft)
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08-09-2010, 09:29 PM
#8
Banned
He should not loose speed until he hits his top HP as long as he has a decent speed governor on the engine.
08-09-2010, 09:29 PM
#9
Administrator
Thread Starter
I think you've lost me! WHAT 2500 watt requirement? I need 10k to run the office when the power goes out and I was looking for a way to use an engine that I already have.
You're about as helpful as I am! 
Good point.
Good point.
08-09-2010, 09:36 PM
#10
With age comes the cage
I have actually seen that done.. Not with a new Liberty thou.
It is a preferred setup with the local farmers on their irrigation pumps to find an old 4x4 truck pull the bed mount the pump on the back use the rear drive-line to run the pump.. Put it in 4wd to move the truck / pumps suction line in and out of the river..
It is a preferred setup with the local farmers on their irrigation pumps to find an old 4x4 truck pull the bed mount the pump on the back use the rear drive-line to run the pump.. Put it in 4wd to move the truck / pumps suction line in and out of the river..
08-09-2010, 09:43 PM
#11
With age comes the cage
What kinda equipment you have in that office? that is approx. 85 amps..
08-09-2010, 09:50 PM
#12
Administrator
Thread Starter
5 computers, 2 of which are servers, 3 printers, 3 a/c units, exhaust fans in the shop, shop lights, a few plugs for grinders, saws, etc., and the ever important coffee machine. We don't like to stop working when the power goes out, and it goes out for days at a time.
08-09-2010, 09:57 PM
#13
With age comes the cage
Wait a minute there buddy you said office now your throwing in shop equipment...
I found the solution to your problem..it is a gen set / air compressor / welder, you can keep the puters a puting / coffee cups full / AC on high and still lay-down some low-hy..and jump start your Liberty if the need arises!!
http://www.millerwelds.com/products/...r_302_air_pak/
I found the solution to your problem..it is a gen set / air compressor / welder, you can keep the puters a puting / coffee cups full / AC on high and still lay-down some low-hy..and jump start your Liberty if the need arises!!
http://www.millerwelds.com/products/...r_302_air_pak/
08-10-2010, 04:20 AM
#14
I wish I was as fine, as those who work the pipeline!
Ok Scott, I think I've got it figured out for ya...
Get your self a tread mill. Put a large cage around it, strap blake or eric onto the treadmill so they can't move forward or backward and put a sheep in front of them. Extend the rear axle to your generator (direct drive). If you don't get 16 HP right away, try tying a couple of bows on the sheep, if that doesn't get you enough, try sheering the sheep nice and clean, and/or moving the sheep a little closer, but please make sure she is out of reach. Oh ya, one more thing, make sure the sheep is facing away from them. Might also need to rig up a drool bucket or they could slip. Could cause you a momentary loss of power.
Might also want to consider a large drape to cover everything up, in the event of an accidental capture. Could be rather unsightly and very disturbing.
Guaranteed 16 HP.
Hope this helps buddy!!!
Get your self a tread mill. Put a large cage around it, strap blake or eric onto the treadmill so they can't move forward or backward and put a sheep in front of them. Extend the rear axle to your generator (direct drive). If you don't get 16 HP right away, try tying a couple of bows on the sheep, if that doesn't get you enough, try sheering the sheep nice and clean, and/or moving the sheep a little closer, but please make sure she is out of reach. Oh ya, one more thing, make sure the sheep is facing away from them. Might also need to rig up a drool bucket or they could slip. Could cause you a momentary loss of power.
Might also want to consider a large drape to cover everything up, in the event of an accidental capture. Could be rather unsightly and very disturbing.
Guaranteed 16 HP.
Hope this helps buddy!!!
