Close and Latch rating

[mshields]

I'm editing a UL 1558 switchgear spec. I'm specifying that it be 85kAIC rated but then the guideform spec I'm using indicates that "Close and Latch ratings for all frame sizes is available in up to 65kAIC rating. How does one determine what this should be and what signifcance does this rating have. Is it for automatic throwover scenarios where a breaker might try to automatically close into a fault? If so, what if you have an available over 65kAIC?

Thanks,

Mike

 

[SG-1]

Westinghouse type DHP went up to 77KA on Close & Latch in both 5 & 15 KV. The 5KV had primary disconnects the size of pie plates.

There are four main ratings associated with breakers

Breaker Open = Rated Voltage
Breaker Closed = Rated Current
Breaker Open to Close = Close & Latch
Breaker Close to Open = Short Circuit Amps

Close & Latch is basically the maximum current that the breaker can successfully close on.