Generator breaker sizing

[hhsting]

I have 500kva generator with 480V three phase. There are two breakers at generator provided one is 600A and another is 200A. The generator has internal overload protection.
600A breaker has 600A cable
200A breaker has 155A cable size feeds motor load only

So generator
Full load is 601A.

601x1.25=751A next standard size is 800A.

Would those breaker be correct size or too large? Reason is i dont find anything in 445, 700,701 NEC 2017.

 

[petersonra]

I have 500kva generator with 480V three phase. There are two breakers at generator provided one is 600A and another is 200A. The generator has internal overload protection.
600A breaker has 600A cable
200A breaker has 155A cable size feeds motor load only

So generator
Full load is 601A.

601x1.25=751A next standard size is 800A.

Would those breaker be correct size or too large? Reason is i dont find anything in 445, 700,701 NEC 2017.

seems to me if the generator manufacturer supplied them, they are probably correct. you think an 800 A CB is correct, they supplied 600 and 200 A breakers which is 800 A.

if you overload the generator motor it will just trip anyway.

 

[hhsting]

seems to me if the generator manufacturer supplied them, they are probably correct. you think an 800 A CB is correct, they supplied 600 and 200 A breakers which is 800 A.

if you overload the generator motor it will just trip anyway.

Generator manufacturer is not providing. The generators breakers are provided by contractor they buy and install at the generator. The generator internal overload and generator is provided by generator manufacturer

 

[electrofelon]

I have 500kva generator with 480V three phase. There are two breakers at generator provided one is 600A and another is 200A. The generator has internal overload protection.
600A breaker has 600A cable
200A breaker has 155A cable size feeds motor load only

So generator
Full load is 601A.

601x1.25=751A next standard size is 800A.

Would those breaker be correct size or too large? Reason is i dont find anything in 445, 700,701 NEC 2017.

I dont see anything in the NEC requiring sizing of these breakers. I think per 445.12(A) you are all set because you say the generator has internal overload protection. If you were picky, you could put note on plans to follow any manufacturer instructions in regards to the breaker sizing per 110.3(B).

Keep in mind the full load current is likely quite a bit higher than 600A. Typically a generator can put out rated output at 80% power factor so I would expect full load current to be more like 750 amps.