Siemens 5SY3103-7 SENTRON MCB — 1P C 3 A, 4.5 kA
It breaks fault currents up to 4.5 kA per EN 60898 and 6 kA per IEC 60947-2, with a DC rating of 15 kA at 72 V per IEC 60947-2 and 5 kA per UL 1077 / CSA C22.2 No.235. That means it handles the standard residential and light-commercial fault levels you'd expect from a 6 kA-rated MCB, with headroom for DC circuits up to 72 V — useful for control transformers or DC bus protection in a panel. The 18 mm width (1 width unit) snaps onto a DIN rail via the quick-assembly system, and the combined top/bottom terminals accept solid or stranded copper from 0.75 to 35 mm². That's a wide wire range — you can land a 35 mm² feed on a 3 A breaker if you need a tap, though in practice you'd usually run 1.5 to 6 mm² for this ampacity. The sealable design (yes) and touch protection (yes) make it suitable for panels that require lockable covers or finger-safe terminals per IP20 with conductors connected.
Ambient range -25 to +55 °C, storage -40 to +75 °C, with humidity derating above 55 °C.
Compliance & Approvals
Rated per EN 60898 (4.5 kA) and IEC 60947-2 (6 kA AC, 15 kA DC), plus UL 1077 / CSA C22.2 No.235 (5 kA AC). Overvoltage category III. Energy limiting class 3. Halogen-free and silicon-free construction. The part carries the standard SENTRON compliance documentation — RoHS, REACH, and the applicable CE/UKCA marks for the European market.