Siemens SENTRON 5SL4114-7 — 0.3 A C-curve MCB, 1-pole, 10 kA
The Siemens 5SL4114-7 is a 1-pole miniature circuit breaker from the SENTRON series, rated 0.3 A with a C-curve trip characteristic. It interrupts fault currents up to 10 kA per EN 60898 and IEC 60947-2 at 400 V AC — enough for residential and light commercial distribution boards where the prospective short-circuit current stays under that threshold. C-curve means the magnetic trip fires at 5 to 10 times rated current (1.5 to 3 A for this 0.3 A unit), so it handles moderate inrush from small transformers or capacitor banks without nuisance tripping. The 0.3 A rating makes it a fit for low-current branch circuits — control transformers, signal supplies, or lighting strings. Rated voltage is 250 V AC single-phase, 440 V AC multi-phase; frequency 50/60 Hz. The 1-module-wide (18 mm) body snaps onto standard DIN rail and accepts supplementary devices (auxiliary contacts, shunt trips, undervoltage releases) — useful when you need remote signaling or emergency shutdown on that circuit.
Temperature derating and mounting
The 0.3 A rating holds at 30 °C ambient. At 40 °C derate to 0.28 A; at 45 °C to 0.26 A; at 55 °C to 0.24 A. No special ventilation needed — the breaker can be mounted in any position, and the IP20 rating (with conductors connected) is standard for enclosed distribution boards. Mechanical life is 10 000 operating cycles typical. Power loss per pole at rated current in hot state is 0.9 W — negligible for panel thermal budgeting in a populated DIN-rail enclosure.