The 320 A rating is at 65 °C ambient — that's the full nameplate, no derating required at typical 40 °C panel internal temps. The MicroLogic 2.3 M is an electronic trip unit, so it gives you adjustable long-time (L), short-time (So), and instantaneous (I) protection curves. The breaker is Category A (no intentional short-time delay for selectivity), so it's meant to trip fast on a fault — coordinate it with a downstream contactor or starter, not with another breaker in a selective chain.
Front connections both top and bottom, so you can bus straight through without flipping the breaker. The 140 mm width and 255 mm height fit a standard MCC bucket. IP40 enclosure protection, IK07 impact rating — fine for a clean indoor switchroom, not for washdown.
The ComPacT NSX platform is Schneider's mainstream MCCB line, so spares and accessories (trip units, rotary handles, shunt trips, auxiliary contacts) are widely available. The 6 accessory slots on the breaker let you add alarms, aux contacts, or a motor operator without changing the base unit. If you're freezing a BOM for a motor control centre, this is a stable line to spec.