Instantaneous CB setting

[skyline77]

What is the minimum instantaneous breaker settings in amps needed for a three-phase, 200Hp, 575 volt rated code B motor?

Per Table 430.250 FLC = 192 A.
Per Table 430.52 for AC polyphase motors other than wound rotor:
800% of FLC = 1536 A.
Per Table 240.6(A) CB should be 1200 A.

However, per Table 430.7(B) LR is 3.54,
So, 200 hp * 3.54 = 708 kVA
So I = 711 A
Per Table 240.6(A) CB should be 800 A.


Which one is accurate?

 

[ptonsparky]

The minimum is whatever it will start at. IMO a design issue.
Maximum is what the NEC is concerned with.
You can be in between the two.

 

[bwat]

Is the instantaneous breaker function the only OCPD that is accomplishing the short circuit and ground fault protection? That's the purpose of table 430.52 with regards to the 800%.

Asked another way, is the breaker magnetic/instantaneous only? Or is it something that has adjustable LSIG and you're just asking about the "I" portion?