What this 4-pole D-curve MCB delivers in a dusty, hot panel
The Siemens SENTRON 5SY8401-8 is a 4-pole miniature circuit breaker with a D tripping characteristic, rated at 1 A AC and 70 kA breaking capacity per IEC 60947-2. Rated for the heat, not the office: it's certified for -40 °C to 75 °C ambient, and the current derates to 0.98 A at 50 °C and 0.95 A at 55 °C — so if your panel runs hot, you don't lose the branch.
Mounting and integration — 4 MW units, any position
Mounting position is any, so you can lay it sideways in a shallow gland plate if needed. Combined terminal top and bottom accepts busbars or ring lugs; the sealable cover keeps operators from toggling the handle without authorization.
Breaking capacity and compliance — the numbers that matter for coordination
The 70 kA at AC per IEC 60947-2 is the headline — that's the ultimate short-circuit breaking capacity at 400 V, giving you headroom for high-fault installations. For DC circuits, it's rated 15 kA per the same standard. If you're exporting to North America, note the UL 1077 / CSA C22.2 No.235 rating is 5 kA at AC — that's the supplementary protector rating, not the branch-circuit rating. Vibration resistance per IEC 60068-2-6 (±1 mm at 5-25 Hz, 50 m/s² at 25-150 Hz) means it holds up on a conveyor drive panel or near a kiln shell.