Siemens 5SY4514-7 — SENTRON MCB, 0.3 A C-Char, 10/35 kA
The Siemens 5SY4514-7 is a SENTRON miniature circuit breaker in a 1P+N (2-pole) configuration, switching both phase and neutral. Rated 0.3 A at 35 °C with a C tripping characteristic, it is sized for protecting control transformers, signal-conditioning modules, or small auxiliary circuits — not motor or general-power loads. The C curve (5–10× In magnetic trip) handles moderate inrush from small inductive or capacitive loads without nuisance tripping. Breaking capacity is dual-rated: 10 kA per EN 60898-1 for domestic/commercial distribution boards, and 35 kA per IEC 60947-2 for industrial panel applications where higher fault current is available. The 35 kA figure under 60947-2 means this breaker can safely interrupt a fault up to that level without upstream fuses needing to clear first — useful in a sub-distribution board fed by a transformer with low impedance. Current derating is published across the operating range: 0.3 A at 35 °C, 0.28 A at 40 °C, 0.27 A at 45 °C, 0.26 A at 50 °C, 0.25 A at 55 °C, and 0.24 A at 60 °C. Ambient temperature inside a sealed panel often runs 10–15 °C above room temperature, so the 40 °C or 50 °C column is the one to size against for a real installation.
Panel fit and integration
Occupies 2 modular width units (36 mm) on a DIN rail, with a depth of 76 mm and an installation depth of 70 mm behind the panel face. The quick-assembly fastening system clips onto the rail without tools; mounting position is any orientation. IP20 with connected conductors — suitable for enclosed distribution boards and control panels, not for wet or washdown zones. Combined terminals top and bottom accept the incoming supply on either side — no fixed line/load orientation. Neutral conductor is switched (1P+N design), so the neutral is disconnected when the breaker is off, which matters for isolation of single-phase control circuits. Sealable design allows the installer to lock the toggle position with a padlock for lockout/tagout.
Lifecycle and compliance
Rated to IEC/EN 60898-1 and IEC/EN 60947-2 / UL1077, covering both the domestic MCB standard and the industrial circuit-breaker standard. Overvoltage category III, pollution degree 3. Halogen-free and silicon-free construction. Humidity limits: max 95% RH up to 55 °C, derating to 35% RH at 75 °C.