OCPD LOCATED IN MEDIUM VOLTAGE SWITCHGEAR

[m sleem]

One of the outgoing medium voltage (13.8KV) circuits feeding #5 XFMRs each is 1500KVA, what would be the breaker size as code says in 430.3(A)?

1- 6x of #5x1500kva.
2- 6x of 1500kva.

 

[weressl]

One of the outgoing medium voltage (13.8KV) circuits feeding #5 XFMRs each is 1500KVA, what would be the breaker size as code says in 430.3(A)?

1- 6x of #5x1500kva.
2- 6x of 1500kva.

The breaker size would be determined by the feeder size in 1, not by 430 rules, but even in the case of 2 the CT and protective relay would be sized according to IEEE/ANSI coordination study rules that pretty much overrides 430. Minimum breaker size @ 15kV class gear is 600A, typically.

 

[m sleem]

The breaker size would be determined by the feeder size in 1, not by 430 rules, but even in the case of 2 the CT and protective relay would be sized according to IEEE/ANSI coordination study rules that pretty much overrides 430. Minimum breaker size @ 15kV class gear is 600A, typically.

Sorry Weress, that was my mistake. The written no 1&2 it is only one case but i wrote to indicate my proposal for two different approach & check which one would be correct.

 

[m sleem]

One of the outgoing medium voltage (13.8KV) circuits feeding #5 XFMRs each is 1500KVA, what would be the breaker size as code says in 430.3(A)?

1- 6x of #5x1500kva.
2- 6x of 1500kva.

TYPO 430.3 to be 450.3.