Determining when MCCBs have been compromised and
should be removed from service has been problematic to the
traditional end user, even to users with skilled maintenance
forces. When a MCCB interrupts a high level fault at or near
the device interrupting rating, there is no easy way of knowing
after the fault has been cleared that the breaker can be reset
and is suitable for continued service. Internal damage that
occurs during repeated high level fault current interruption
could affect the breaker’s ability to interrupt a future fault,
thereby potentially compromising its performance. If potential
problems were known in advance, the user might elect to
remove the breaker from service, replacing it with a new one.