Siemens SENTRON 5SY8214-8 — 2-pole D-curve MCB for high-fault industrial panels
The Siemens SENTRON 5SY8214-8 is a 2-pole miniature circuit breaker with a D tripping characteristic, rated at 400 V AC and a breaking capacity of 70 kA per IEC 60947-2. At DC per IEC 60947-2 it breaks 15 kA; under UL 1077 it is rated 5 kA.
Thermal derating and environmental tolerance
Rated current is 0.3 A at 45 °C, derating to 0.29 A at 50 °C and 0.28 A at 55 °C. The breaker operates across -40 °C to 75 °C, with humidity tolerance up to 95% at 55 °C, 55% at 70 °C, and 35% at 75 °C. Vibration resistance per IEC 60068-2-6: ±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz, so it holds calibration in machinery-mounted enclosures.
The sealable design allows panel builders to lock settings after commissioning. Halogen-free and silicon-free construction avoids outgassing issues near sensitive electronics or in clean-room environments.