50 A C-Curve MCB for Panel Protection
The Siemens 5SY7550-7 is a 50 A miniature circuit breaker from the SENTRON 5SY7 series, designed for 1P+N (single-pole plus neutral) branch circuit protection in industrial control panels. Its C tripping characteristic (5–10× In) handles moderate inrush from motor starters, contactor coils, and small transformers without nuisance trips, while still clearing low-impedance faults fast enough for cable protection. Rated 230 V AC with a breaking capacity of 15 kA per EN 60898 and 20 kA per IEC 60947-2, this MCB is sized for sub-distribution boards where the prospective fault current stays under those thresholds. The 72 V DC maximum rating (per IEC 60947-2, 15 kA) covers control-circuit DC supplies, though the primary application is AC branch protection.
Mounting and Integration
Mounts via the quick-assembly system onto standard DIN rail — 36 mm width (2 width units), 90 mm height, 76 mm depth. Installation depth is 70 mm. The IP20 rating (with connected conductors) means it is intended for enclosed panel use, not washdown or outdoor exposure. Ambient temperature range of -40 to +70 °C covers most indoor industrial environments; storage range extends to -40 to +75 °C. Terminals accept solid or stranded conductors from 0.75 to 35 mm², with combined top and bottom terminals for daisy-chaining. Sealable design allows panel-lockout procedures. Mounting position is any, and the supply cord position is any — no orientation restrictions for panel layout.
Environmental and Compliance
Halogen-free and silicon-free construction, suited for sensitive environments like semiconductor fabs or clean rooms where outgassing must be minimized. The MCB is rated for mechanical engineering and industry applications per its suitability designation. Humidity derating applies: max 95% RH up to 55 °C, derating to 55% at 70 °C and 35% at 75 °C — relevant for panels in hot, humid locations.