Siemens 5SL4401-6 — 4-pole B-curve MCB at 1 A, 10 kA
The 400 V AC rated supply voltage and 440 V AC multi-phase maximum suit it for three-phase distribution panels where each pole protects a phase or neutral.
The B-curve means the magnetic trip operates at 3 to 5 times rated current (3–5 A for this 1 A unit), so it is sized for resistive and lighting loads with low inrush — not motor or transformer circuits where a C- or D-curve would be needed. The 1 A rating is at 30 °C ambient; at 40 °C it derates to 0.96 A, at 55 °C to 0.9 A — factor this into continuous load sizing if the enclosure runs warm. The 4-pole configuration (4P) switches all four conductors — three phases plus neutral — with no separate neutral pole switching (the product function confirms neutral conductor switching is not provided). This is standard for three-phase final circuits where the neutral is switched with the phases. The 72 V DC maximum rating per pole means it can also protect DC control circuits up to that voltage, though the primary application is AC.
Halogen-free and silicon-free construction meets the material restrictions common in rail, marine, and data-center installations where outgassing during a fault must be minimized. The mechanical service life of 10 000 operating cycles is typical for an MCB in a distribution panel where it sees infrequent manual switching.