The Siemens SENTRON 5SY5250-7 is a 2-pole miniature circuit breaker with a C-trip curve, rated for universal current operation (AC/DC). It breaks 10 kA per IEC/EN 60898-2 and 15 kA per IEC 60947-2 at DC, so it handles both residential-style fault levels and industrial-grade DC rail faults. The C-curve (5–10× In) is the standard pick for motor starters, small transformers, and general branch circuits where a moderate inrush won't nuisance-trip.
Fit and mounting
Snaps onto DIN rail via the quick-assembly system — 2 modular width units (36 mm wide) — and can mount in any position. Depth is 76 mm (70 mm installation depth), so it clears standard 80 mm deep enclosures. The combined top and bottom terminals accept supply from either end; for DC wiring, observe polarity as marked. IP20 with conductors connected, pollution degree 3, overvoltage category III — typical for a distribution board or sub-panel.
Standards and compliance
Dual-rated to IEC/EN 60898-2 and UL 1077, which means it's accepted for both IEC-style distribution boards and UL-recognized supplementary protection. Halogen-free and silicon-free construction — no silicone outgassing to foul contacts in sealed panels. Ambient operating range -40 °C to 75 °C, with humidity derating above 55 °C (95% RH at 55 °C, 55% at 70 °C, 35% at 75 °C). Vibration resistance per IEC 60068-2-6: ±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz.