The 5SJ4240-8HG41 is a 2-pole SENTRON miniature circuit breaker with a D tripping characteristic, meaning it tolerates the high inrush currents typical of motor, transformer, and welding loads without nuisance tripping — the magnetic trip fires at 10–20× rated current, not the 5–10× of a C-curve. On the 400 V AC side it breaks 10 kA per EN 60898 (the standard for household-type MCBs in final circuits) and 15 kA per IEC 60947-2 (the industrial standard for isolating and switching in control panels). At 60 V DC the breaking capacity drops — the datasheet lists the DC rated value at 60 V maximum, so this is not a primary DC breaker for battery banks or solar strings; it is an AC mains breaker that also handles low-voltage DC control circuits.
Halogen-free and silicon-free construction, which matters in clean-room or semiconductor-adjacent installs where outgassing can contaminate optics or contacts. Vibration resistance rated at 50 m/s² over 25–150 Hz and 60 m/s² at 35 Hz — survives the typical machine-mounted enclosure shake. Sealable design allows the panel builder to lock the handle position with a padlock for lockout/tagout compliance.