What this MCB is and what it does
The Siemens 5SP4392-7 is a SENTRON 5SP miniature circuit breaker, 3-pole, with a C-trip characteristic rated at 125 A and a breaking capacity of 10 kA per EN 60898 at 400 V AC. That 10 kA rating means it can safely interrupt a fault current up to 10,000 amps without welding its contacts or failing to clear — essential for protecting branch circuits in a distribution board where the prospective short-circuit current is known to be at that level. The C-curve (trips between 5 and 10 times rated current) suits it for moderate inrush loads like small motors, transformers, or lighting banks where you need to ride through the start-up surge without nuisance tripping.
Mounting and panel fit
Mounts on DIN rail or with screw fixing in any orientation. At 4.5 modular width units (81 mm wide, 76 mm deep, 90 mm tall) it fits standard SENTRON distribution boards and sub-distribution panels. The 70 mm installation depth leaves clearance for tunnel terminals top and bottom — no need to rework the enclosure if you're swapping in from a similar 3-pole MCB. Sealable design allows lockout/tagout compliance on critical circuits.
Environmental and compliance
Halogen-free and silicon-free construction, rated for pollution degree 3 and overvoltage category III. Operating temperature range -40 °C to 75 °C with up to 95% relative humidity. Vibration resistance per IEC 60068-2-6 and shock resistance per IEC 60068-2-27 — suitable for industrial panels on conveyors, pumps, or machine tools where mechanical stress is a factor.