This digest investigates the current protection and soft start functions of a three-phase solid-state circuit breaker (SSCB) in the motor control center (MCC). The proposed SSCB integrates application-specific protection functions of soft starter, contactor, circuit breaker, and thermal relay. Three key design considerations, including semiconductor device selection, metal oxide varistor and snubber selection, and heat sink selection are introduced. The fault current protection of the SSCB was tested and verified at 200A by a pulse test platform with a microseconds-level fault current clearing time. Finally, the soft start function was analyzed and realized without zero current detection.
