generators

1 HP = 746W or 0.746KW (approx)

You are looking at 7.46KW to match the rating. Factor a good overhead margin and 10-15KW should suffice.

KW is only 1 spec to account for--You also need to match nameplate voltages. Your generator will also need a prime mover (Ie. something to rotate the generator) If this is electrical it will also need to be at least 10KW.

power out = power in * effiicency Efficiency is never greater than 1.0

Thanks, that's very helpful. I don't understand the prime mover, is that a pallet jack so I can move the generator? It is a electric motor.

hi Dan,

generators convert mech energy into electricity so this mechanical energy (motion of the generator shaft) comes from the prime mover..

eg. water turbines.. the high pressure water falls with great kinetic energy and run a turbine.. this turbine is connected to the shaft of your generator..

so thats the prime mover..

Beatenblood is right, and yes, a prime mover can be an electric motor.

Falling water, wind, or tides are all valid prime mover's

Residential use generators typically use a gas motor as a prime mover, to turn the generator shaft.

Back to your 3PH motor in question, beware that starting a motor (Simple on/off switch) also requires initial "in rush" current which needs to be accounted for when sizing a generator. A typical 3Ph fan motor (10HP) may draw 150-200% of it's nameplated amps to get started. Most industrial generators are designed to handle this type of short terrm load, but the residential ones may not be.

Adding to this statement, the use of and development of DFD, frequency drive units to actually help control this on-rush, voltage spyke, is the next step in your equipment listing for a more permanent installation. Good luck with your build.

Maximo

As a rule of thumb, you can assume that a three phase motor will consume 1 KW per HP to run, and 2 KW per HP to start. With that in mind, I would suggest a 20 KW generator to operate your 10 HP motor. The inrush would be adequately handled by the 20 KW. After starting, the motor would run on 10 KW. This is assuming a standard induction motor starting across-the-line. As mentioned above, VFD's or "soft starters" would lessen the starting KW. As I said, this is a rule of thumb, but it has worked for me for many years. If there are other motors that would be operating from the same generator, the rules change somewhat. In a duplex pumping application for instatnce, the rule would apply to the first motor. However, the second motor would have to start with the first already running. Therefore, the requirement for two 10 HP motors would be a 30 KW unit - 1 KW for the operating motor and 2 KW to start the lag pump. But, back to your single 10 HP motor, use 20 KW.

The recommendation of 1 kW/HP is a good one with 2 kW/HP for starting the motor across the line also a good suggestion for this size, especially if you plan for an engine for the 'prime mover' (the driver). So buy a unit with 20 kW capacity but ask if this capacity is for continuous 24/7 duty or temporary duty. You will want 10 kW continuous 24/7 duty and 20 kW temporary. In these small machines it will be difficult to get such answers because it is so small, and the sales people may not be used to such questions which are typical for 150 kW type units or larger. Research the model throughly to get the best answer to the 'continuous duty' question. One more VERY VERY VERY important thing is that if you choose an engine driver, your altitude and ambient temperatures will drastically effect output. Small engines will loose 3% for each 1000 ft altitude above 500 ft so if you live where I do at 6500 ft, that's 18% power loss. Since the air is thinner, any cooling will suffer also. Make sure the unit is 'rated' for your altitude and temperatures.

Cheers