The Schneider Electric C6331M500 is a MicroLogic 1.3 M electronic trip unit for the ComPacT NSX630 molded-case circuit breaker platform, rated 500 A at 65 °C and built for motor protection per EN/IEC 60947-2. This is the drop-in replacement trip unit for an NSX630 frame — you swap the trip unit, not the breaker — so if your BOM calls out C6331M500, the fit is direct into the NSX630 cradle.
What the protection settings mean for your motor circuit
This trip unit uses electronic (not thermal-magnetic) sensing, which gives you adjustable short-time protection (Isd) across nine settings from 2500 A to 6500 A, with a fixed instantaneous pickup (Ii) at 6500 A. For a motor start, the adjustable short-time delay lets you ride through inrush without nuisance tripping — set Isd high enough to clear the locked-rotor current, and the instantaneous backup catches a hard fault. The 3D protected poles description means all three poles are monitored for overcurrent; there's no ground-fault module on this variant.
The trip unit snaps into the fixed-mounted NSX630 breaker — no wiring changes at the breaker terminals. IP40 front-of-panel protection keeps tools and fingers out. The green flashing LED signals the trip unit is powered and ready, which is useful during commissioning when you're verifying control voltage before closing the breaker.