The C40N32M320: The 85 kA Icu at 240 V AC and 50 kA at 415 V AC mean this breaker can safely interrupt a fault current up to those levels without welding contacts or rupturing the housing. At 690 V AC it still holds 10 kA Icu. For a motor protection circuit on a 480 V supply (common in North American plants), the 50 kA Icu at 480 V AC per UL 60947-4-1 covers most service-entrance and downstream feeder applications — you won't need a current-limiting fuse upstream unless the available fault current exceeds that figure.
Motor protection trip curve and thermal memory
The MicroLogic 2.3 M provides L (long-time overload), So (short-time short-circuit with fixed delay), and I (instantaneous) protection, with selectable motor tripping classes 5, 10, and 20. The 20-minute thermal memory before and after tripping means the breaker 'remembers' prior heating — critical for motor starts in quick succession where a cold-start trip curve would allow a second start that a hot motor shouldn't get. This prevents nuisance trips on restart while still protecting the motor winding.