The C403400DS is a ComPacT NSX400NA DC switch disconnector from Schneider Electric's ComPacT range, built for DC distribution and isolation duties. The 750 V DC insulation voltage (Ui) and 8 kV impulse withstand (Uimp) confirm it's designed for grounded DC systems up to that voltage, with pollution degree 3 (conductive pollution, typical in industrial enclosures) per IEC 60664-1.
The headline number is 400 A at 750 V DC in DC-22A duty. If your enclosure runs hotter than 40 °C, you'll need to apply the manufacturer's thermal derating curve (not provided here, but standard for the ComPacT family). Short-circuit performance: the rated short-time withstand (Icw) is 7.5 kA for 1 second, and the making capacity (Icm) is also 7.5 kA as a switch-disconnector alone. That means it can close onto and hold against a fault up to 7.5 kA peak — enough for most DC distribution panels fed from a battery bank or rectifier, but if your available fault current exceeds that, you'll need upstream current-limiting fuses or a breaker with higher interrupting rating. Mechanical durability is 5000 cycles, electrical durability 1000 cycles at rated 750 V DC and 400 A. That's typical for a switch-disconnector in distribution service — not a daily-operating contactor, but fine for infrequent isolation and switching. If your application cycles the switch more than a few times a week, consider a contactor instead.
Fixed-mount on a backplate — no DIN rail option. IP40 enclosure protection means it's not for washdown areas, but fine inside a standard industrial panel. IK07 impact resistance handles light knocks during installation. Class II electrical shock protection — no earth connection required. Toggle control with a contact-position indicator so you can see open/closed status at a glance.