Siemens SENTRON 5SY8401-7 — 4-pole C-curve MCB, 1 A, 70 kA
It belongs to the SENTRON series, designed for mechanical engineering and industrial panel applications where branch-circuit protection and selectivity matter.
Thermal derating and environmental limits
At 45 °C ambient the 1 A rating holds; at 50 °C it derates to 0.98 A, at 55 °C to 0.95 A. The surrounding temperature influence spec caps humidity at 95% up to 55 °C, 55% up to 70 °C, and 35% up to 75 °C — so in a sealed, non-ventilated enclosure near heat sources, check the actual ambient against the derating curve.