63 A B-curve MCB for railway and industrial panels
The Siemens SENTRON 5SY4163-6KK11 is a 1-pole miniature circuit breaker rated 63 A at 35 °C with a B-curve tripping characteristic. Per the datasheet, the breaking capacity is 10 kA under EN 60898 and 15 kA under IEC 60947-2 — the higher figure applies when the installation is designed to the industrial standard rather than the household one. The B-curve means the magnetic trip operates between 3 and 5 times rated current, so it suits resistive and general-purpose loads where inrush is modest; it is not intended for motor-starting duty where a C or D curve would be needed. The part is designed for railway applications per the manufacturer's designation, and it is rated for overvoltage category III with pollution degree 3 — meaning it is suitable for fixed installations inside enclosures where transient overvoltages from the supply are present and the environment may have conductive dust or condensation. The IP20 rating applies with conductors connected, so the terminals themselves are finger-safe but the unit requires enclosure protection against moisture.
Temperature derating and mounting
The 63 A rating holds at 35 °C ambient. Above that, the continuous current must be derated: 59.16 A at 40 °C, 57.14 A at 45 °C, 55.06 A at 50 °C, 52.92 A at 55 °C, and 50.65 A at 60 °C. If the panel ambient runs above 35 °C, the load current must be checked against this curve — the breaker will carry the derated value without nuisance tripping, but a full 63 A load at 50 °C will cause thermal trip. The unit occupies one modular width of 18 mm on a DIN rail, with a depth of 76 mm and an installation depth of 70 mm. The fastening method is the quick-assembly system — it snaps onto the rail and can be removed with a screwdriver without disturbing adjacent units. Mounting position is any, which simplifies layout in crowded enclosures. The combined terminal top and bottom accept conductors from either direction.