0.3 A D-curve MCB for short-circuit protection of inductive or high-inrush loads
The Siemens 5SY4114-8 is a 1-pole SENTRON miniature circuit breaker with a D tripping characteristic, rated 0.3 A at 400 V AC. The D curve means it tolerates brief inrush spikes up to 10–20× rated current before tripping — sized for loads like small transformers, solenoid valves, or motor starters where the initial surge would nuisance-trip a B or C curve. Breaking capacity is 10 kA per EN 60898 for general distribution panels, and 35 kA per IEC 60947-2 when installed in an industrial panel with higher fault current potential. At DC it's rated 72 V maximum with 15 kA interrupting capacity per IEC 60947-2.
Panel integration and wiring
Mounts on DIN rail via the quick-assembly system, occupying 1 width unit (18 mm). Terminal accepts solid or stranded conductors from 0.75 to 35 mm² at both top and bottom — combined terminal design means one wire per side. Installation depth is 70 mm; overall depth 76 mm. IP20 with conductors connected, so it's enclosed within a panel but not rated for wet environments. Sealable, touch-proof terminals. Ambient range -40 to +70 °C; storage -40 to +75 °C.
Standards and approvals
Rated for overvoltage category III. Complies with EN 60898 (10 kA), IEC 60947-2 (35 kA AC, 15 kA DC), and UL 1077 / CSA C22.2 No. 235 (5 kA AC). Halogen-free and silicon-free construction. Suitability for operation noted as mechanical engineering and industry.