one electrical engineer
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1) How Does One Size The Generator Feeder Side Overcurrent Protection Device, If One Has A Fire Pump With Wye Delta Starting That Limits The Starting Current To 200% Of Fla Or 33% Of Lra, On A 125 Hp 480volt Motor - Nameplate Shows 907 Amps Lra. Fire Pump Controller Has 250amp Molded Case Switches In It.
I Think A 350 Amp Thermal Mag Circuit Breaker Is Correct Based On 156 fla X 250% (per Nec 430) = 390 Amps And Rounding Down To 350a.
2) On the normal side I am proposing a unfused disconnect 400a, but there is some discussion that this does not cover the LRA, I suppose the disconnect should also have the horepower rating (at least 125 hp rated) to be correct.
Please Confirm Or Show Me Where To Look Further.
I Think A 350 Amp Thermal Mag Circuit Breaker Is Correct Based On 156 fla X 250% (per Nec 430) = 390 Amps And Rounding Down To 350a.
2) On the normal side I am proposing a unfused disconnect 400a, but there is some discussion that this does not cover the LRA, I suppose the disconnect should also have the horepower rating (at least 125 hp rated) to be correct.
Please Confirm Or Show Me Where To Look Further.