The Siemens SENTRON 5SY5263-6KK11 is a 2-pole miniature circuit breaker with B tripping characteristic, rated 63 A at 400 V AC and 440 V DC. Rated for universal current (AC/DC), so it handles DC control circuits up to 440 V without derating the breaking capacity — a useful trait in panels mixing AC distribution and DC auxiliary supplies.
Mounting position is any; the quick-assembly system clips onto the rail without tools. Top and bottom terminals are combined (clamp-type), and the unit is sealable for tamper-proofing after commissioning. Ambient temperature range -40 to +70 °C covers most indoor and outdoor cabinet installations, though the thermal-magnetic trip characteristic shifts with temperature; the humidity derating curve (max 95% RH up to 55 °C, then decreasing) should be noted for sealed cabinets in tropical climates.
Designed for railway applications per the product designation, though it carries standard EN 60898 / EN 60898-2 breaking capacity ratings rather than a dedicated railway standard like EN 50155. Touch protection is integral (finger-safe terminals when wired). The product is classified per DIN EN 61346-2 and DIN EN 81346-2 as function code F (protective device).