The Siemens SENTRON 5SY5208-7CC11 is a 2-pole miniature circuit breaker with a C-tripping characteristic rated at 8 A, built for universal current operation on DC circuits up to 440 V (500 V max). It carries a 10 kA interrupting capacity per IEC 60947-2 at DC — enough to clear a hard fault on a 440 VDC bus without upstream coordination worries. The part is explicitly designed for railway applications, which means it has passed vibration and temperature cycling beyond standard industrial MCBs.
Railway-rated DC protection — what that means on the panel
The 2-pole design switches both lines in a DC circuit; polarity must be observed on the supply connection — the breaker is not polarity-agnostic.