What it is and what it does
The Siemens SENTRON 5SY4280-7CC is a 2-pole miniature circuit breaker rated 80 A with a C tripping curve, designed for 400 V AC systems and capable of interrupting fault currents up to 10 kA per IEC 60947-2. The C-curve (5–10× In) means it holds through motor inrush and transformer magnetizing currents without nuisance tripping, making it the standard choice for general-purpose branch circuits feeding inductive loads like contactors, relays, and small motors. The 10 kA breaking capacity at 400 V AC is enough for most industrial panelboards with a transformer-fed supply; if your available fault current is higher, you'll need to step up to an SENTRON 5SY5 series or a higher-rated 5SY6.
Panel fit and integration
The breaker occupies 2 modular width units (36 mm) on a DIN rail, with a depth of 76 mm and height of 90 mm. It snaps onto the rail via the quick assembly system and can be mounted in any position. The IP20 rating (with connected conductors) is standard for enclosed panel mounting — not for wet or outdoor locations. The combined terminal at top and bottom accepts both busbar and conductor terminations, which simplifies panel wiring when feeding a downstream distribution block or another breaker.
Environmental and compliance notes
Rated for ambient temperatures from -40 °C to +75 °C, with derating above 55 °C as per the humidity/temperature influence table. Halogen-free and silicon-free construction — relevant for clean-room or sensitive electronics environments where outgassing matters. Pollution degree 3 and overvoltage category III, so it's suitable for fixed industrial installations where the supply is a permanent mains connection. The vibration resistance (±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz per IEC 60068-2-6) means it holds up on machine-mounted panels near rotating equipment.