Generator Output

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aarifisher

Member
I need to buy a 400 amp generator for a local grocery.
So i was looking at the specs. Of a 130kw generator and the rated amps is 451a
Now, I made the calculation as 130,000 / 360 = 361amps
So I contacted the manufacturer and this is the answer i got
(130,000 (kw) / 208(VAC) * 1.73 * 0.8 (Power factor) = 451A output)
Now, to my understanding the power factor should reduce the output.
Can someone please explain?
Thank you
 
G

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
110501-1748 EDT

The generator is rated 130,000 watts, not VA, and apparently at an assumed 0.8 PF.

So if the generator was rated in VA, which would be 162,500, then you would multiply by 0.8 to get the wattage at 0.8 PF.

The power rating will in part depend upon the engine size. Assuming 100% efficiency this would be 130,000 / 746 = 175 HP. 175 HP can not provide 162,500 watts of output, but the alternator can be thermally designed to allow 451 A with a 0.8 PF load.

.
 
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hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
Since it's a grocery store, keep in mind refrigeration compressor and HVAC loads too when sizing the generator, the start up current could overload the generator if you are sizing it too close and too many of the loads tried to start at the same time. Load sequencing can help greatly with that.
 
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