Generator feeder sizing

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Hi guys, one quick question:
We have a 40kw gen-set , 3phase 120/208 volt ( not sure of PF yet) install coming up. I was curiouis if I calculate the feeders (from the Generator to the ATS) as a continuous load?
The Generator has a 150 amp main breaker, do I use the actual kw output, or base the feeder size on the 150 main breaker?
I appreciate hearing any input you may have.
 
Hi guys, one quick question:
We have a 40kw gen-set , 3phase 120/208 volt ( not sure of PF yet) install coming up. I was curiouis if I calculate the feeders (from the Generator to the ATS) as a continuous load?
The Generator has a 150 amp main breaker, do I use the actual kw output, or base the feeder size on the 150 main breaker?
I appreciate hearing any input you may have.

If you have a factory installed 150 amp breaker, just size your conductors to that. This sounds like a typical modern genset with a factory installed main breaker. A 3 phase machine in this size range is typically rated at .8 PF, so for this machine the line current would be about 138 amps. The 150 amp breaker would be appropriate.
 
If you have a factory installed 150 amp breaker, just size your conductors to that. This sounds like a typical modern genset with a factory installed main breaker. A 3 phase machine in this size range is typically rated at .8 PF, so for this machine the line current would be about 138 amps. The 150 amp breaker would be appropriate.
And given the short term surge and medium term overload the generator is probably capable of, you should not expect the generator breaker to open under a balanced load except in the case of a sudden dead short, if then.
But the engine will have enough power to let the generator drive a high enough amperage through just one pole of the three pole breaker to trip it.
 
115 % nameplate current ratting of the generator 445.13

If the generator has a factory install breaker then 445.13 doesn't come in to play.

If you have a factory installed 150 amp breaker, just size your conductors to that. This sounds like a typical modern genset with a factory installed main breaker. A 3 phase machine in this size range is typically rated at .8 PF, so for this machine the line current would be about 138 amps. The 150 amp breaker would be appropriate.

Agree, just run 1/0 Cu and be done with it.
 
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