400 V DC power distribution systems for data centers require a fast response DC circuit breaker is required. The semiconductor DC circuit breaker is an important key technology in DC power distribution systems. This paper considers the malfunction of Silicon Carbide- Static Induction Transistor (SiC-SIT) based DC circuit breakers in 400 V DC power distribution systems for data centers. The malfunction mechanism is explained, and a solution is proposed. Investigations are achieved by MATLAB/Simulink and experimental verification.