The Siemens SENTRON 5SY5225-6CC12 is a 2-pole miniature circuit breaker rated for 25 A with a B tripping curve, designed specifically for DC railway applications. It interrupts fault currents up to 10 kA at 440 VDC, with a maximum operating voltage of 500 VDC. The B-curve means it trips at 3–5 times rated current, suited for protecting cable runs and semiconductor loads rather than high-inrush motor circuits.
Physical fit and mounting
At 36 mm wide (2 modular units), 76 mm deep, and 90 mm tall, the 5SY5225-6CC12 mounts on a standard DIN rail via the quick assembly system and can be installed in any orientation. The IP20 rating applies with connected conductors — the terminals are finger-safe but the unit is not sealed against moisture; it belongs inside a railway-rated enclosure. The combined terminals at top and bottom accept both copper and aluminium conductors; polarity must be observed for DC supply.