It protects distribution circuits with LI protection — thermal overload (L) via a bimetal element, and magnetic short-circuit (I) via a fixed instantaneous pickup at 500 A. The 63 A rating at 50 °C is the continuous current the trip unit can carry without nuisance tripping at that ambient; in a 40 °C panel you get a bit of headroom, but if the enclosure runs hotter than 50 °C you need to derate per the thermal curve in the IEC 60947-2 certification. Rated operational voltage goes to 690 V AC 50/60 Hz and 750 V DC, so it handles standard 480Y/277 V and 600 V industrial panels, plus DC bus circuits up to 750 V. The 3-pole 3D configuration means all three poles are protected — no unprotected neutral pole. The long-time pickup is adjustable from 0.7 to 1 x In (44 A to 63 A at 50 °C), with a fixed delay of 120–400 s at 1.5 x In and 15 s at 6 x Ir. That lets you fine-tune the overload curve to the load without swapping the trip unit. The instantaneous pickup is fixed at 500 A — about 8 x In — which is a standard magnetic-only setting for distribution feeders; it won't trip on motor inrush unless the motor's locked-rotor current exceeds that threshold.
This is a trip unit, not a complete breaker — it snaps into the ComPacT NSX100/160/250 frame. The fixed-mount breaker body stays in the panel; the trip unit is the replaceable brain. The Class II electrical shock protection means the trip unit doesn't require a protective earth connection — the double-insulated design handles it.