Home > categories > Electrical Equipment & Supplies > Diesel Generators > Inherited a continuous 12.5 kw, 1800 rpm, 240 volt, single phase, 60 hz generator that requires 25 hp engine?
Question:

Inherited a continuous 12.5 kw, 1800 rpm, 240 volt, single phase, 60 hz generator that requires 25 hp engine?

I inherited a never used generator from a family estate with no motor. After a tornado here last fall I've decided to build a gen-set with it and I have a few questions. 1) Does the 1800 rpm generator mechanical specification mean that the required engine rpm must be a minimum, maximum 1800 rpm or both? Could it be more or is the chance to ruin it a possibility? I want to stay safe.2) Obviously I'm assuming the 25 hp engine requirement is a minimum but how much bigger can it be without wet stacking problems?3) With these generator output specifications can I power my household without damaging anything?I was planning diesel (still researching brands) and connecting direct. Thoughts?

Answer:

The generator probably has to turn at 1800 rpm to maintain the 60 Hz frequency spec. Thisis important in a TV set but I can't think of any where else it would be important. Slocks will be edpendent on line frequency but in an emergency you don' really care if you have a watch. Reet the clocks after the power returns. You will probably use minimum power during a blackout. You need light heat and a book which doesn't use much power. No Alfred Hitchcock or Ray Bradberry.
It means it has to run at 1800 RPM. output voltage and frequency is dependent on RPM. Usually there is a feedback loop that controls the throttle of the engine to maintain the proper RPM and thus the proper output voltage as the load changes. You have to set that up somehow. Don't know what wet stacking problems means. Depends on your household size. A typical US house uses about 1.2 kW average, but there are peaks much higher than that. If your house has electric heat or an electric range or air conditioning, you will have problems.
1) The 1800 RPM specification is the speed which will produce the 60 Hz output. This frequency is critical in some of your household electronics, maybe. If the speed is lower than 1800 RPM, the hertz will be lower. If speed is higher, the hertz will be higher. 2) The 25 HP driver is probably sufficient for your generator. A more powerful engine will not return the value for the extra cost of the larger driver. However, a larger driver will give you perhaps a better frequency control. 12.5 KW is (in theory) 12500 / 746 16.75 HP. I'm not sure what 'wet stacking' is. 3) .It will power most households. You may have some problem starting a large AC unit, if you have your electric clothes dryer, stove, oven and a larger lighting load on at the time it comes on. TexMav

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