The Siemens SENTRON 5SY8310-7 is a 3-pole miniature circuit breaker with a C-curve tripping characteristic, rated 40 kA at 400 V AC per IEC 60947-2 and 5 kA per UL 1077. The C-curve means it holds through inrush up to 5–10× rated current before tripping magnetically — right for motor starters, transformer primaries, and lighting banks where the start-up spike is brief but real. The 40 kA interrupting rating at 400 V AC is the figure that governs fault-clearing capability on an industrial 400 V line; the UL 1077 rating (5 kA) is the supplementary-protector limit for North American panels. Three modular-width units (54 mm) snap onto the DIN rail, and the top/bottom combined terminals accept both busbar and wire without re-termination.
Fastens via the quick-assembly system onto a DIN rail; mounting position is any orientation. Ambient range from -40 °C to 75 °C, with derating for humidity (95% at 55 °C down to 35% at 75 °C). Vibration resistance per IEC 60068-2-6: ±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz. Halogen-free and silicon-free construction, sealable for tamper-evident installations.
The DC breaking capacity is 15 kA at 60 V (max 72 V). For single- or multi-phase AC operation, rated voltage goes to 440 V. The 5 kA UL 1077 / CSA C22.2 No. 235 rating covers supplementary protection in North American panels.