The C10B42D040 is a Schneider Electric ComPacT NSX molded-case circuit breaker in the NSX100B frame, rated 40 A at 40 °C with a MicroLogic 2.2 electronic trip unit. Four poles, toggle control, front-connected — it's built for distribution duty in a backplate-mounted panel.
This breaker delivers 40 kA Icu at 220/240 V AC, 25 kA at 380/415 V, 20 kA at 440 V, and 15 kA at 500 V — all per IEC 60947-2. For a 400 V distribution board, that 25 kA Icu gives you headroom above typical utility fault levels (often 18–22 kA), so you can coordinate downstream without cascading failures. The electronic trip also means you get adjustable long-time and short-time pickup — not just a thermal-magnetic fixed curve.
Connection pitch is 35 mm, and both line and load connections are front-accessed, so you can land cables without pulling the breaker out of the panel. IP40 enclosure protection keeps dust out but isn't rated for washdown — keep it inside a cabinet.