Rated 50 A operational current at AC-3 duty (400 V), it's sized for a 50 A motor load on a 690 V insulation class system. The magnetic instantaneous trip fires at 650 A, so it clears a hard fault without waiting for the thermal element to heat up.
The S3 frame takes 70 mm width — that's roughly four 17.5 mm module slots on the rail. Depth is 174 mm, so you need that clearance behind the panel door; forwards clearance is 167 mm for the handle swing and wiring access. Any mounting position works, and the box terminals accept up to 70 mm² solid or stranded on the main circuit.
The 50 A at AC-3 400 V is the motor-switching rating — that's the one that decides whether this breaker handles your induction motor branch. The 650 A instantaneous trip means it will hold through inrush (typically 6–8 x FLA for a standard motor) but trip immediately on a bolted fault.
Relative humidity 10 to 95 % during operation. Shock resistance 25 g for 11 ms per IEC 60068-2-27 — shrugs off the vibration you'd see on a crusher or conveyor line. RoHS compliance date listed as July 1, 2006, so it's fully RoHS-compliant. Insulation voltage rated 690 V at pollution degree 3, surge voltage resistance 6 kV.