What is the difference between the two interrupting ratings listed for the SB Systems Breaker?
The two ratings for the SB are the Interrupting Rating and the Withstand Rating. The interrupting rating is the maximum fault current that the SB can interrupt while tripping instantaneously. The withstand rating is the current that the SB can hold in WITHOUT tripping for a specified time (i.e. ½ second or 30 cycles). The purpose of the withstand rating is to allow a downstream device, like a branch breaker, to trip first and allow the SB, serving as the main breaker or major feeder, to remain closed and continue to supply power to other areas of the system.
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