Railway-rated DC MCB, 50 A, C-curve
The Siemens SENTRON 5SY5250-7CC11 is a 2-pole miniature circuit breaker rated for universal current, with a C tripping characteristic and a 50 A rating. It is specifically designed for railway applications, carrying a 10 kA breaking capacity at 440 V DC per IEC 60947-2. The C-curve means it handles moderate inrush currents typical of inductive loads like relays and small motors, tripping between 5 and 10 times rated current.
DC voltage and breaking capacity
Rated for DC operation up to 440 V, with a maximum rated voltage of 500 V. The 10 kA breaking capacity at 440 V DC (per IEC 60947-2) is the figure that governs fault clearance on a DC bus — it must exceed the prospective short-circuit current at the installation point. Overvoltage category III and pollution degree 3 suit it for fixed installations in industrial and traction power supplies.
Panel integration and environment
Snaps onto DIN rail via the quick-assembly system, occupying 2 width units (36 mm). Depth is 76 mm, installation depth 70 mm. IP20 with connected conductors — protected against finger contact but not washdown; mount inside a sealed enclosure for wet or dusty environments. Ambient range from -40 °C to 75 °C, with humidity derating above 55 °C. Polarity must be observed on the DC supply; the neutral conductor is not switched.