The Siemens 3VA1050-3ED42-0CH0 is a 4-pole IEC circuit breaker on the 3VA1 frame, rated 50 A with fixed TM210 thermal-magnetic overload protection (Ir = 50 A fixed) and fixed short-circuit pickup at Ii = 10 × In. The neutral conductor is unprotected (solid through), and a nut keeper kit is included for panel mounting.
For a 400 V distribution panel fed by a transformer sized under 1 MVA, that's usually enough to avoid cascading — the breaker clears the fault before upstream devices trip, provided the prospective short-circuit current at its terminals stays under 25 kA. Fixed Ir at 50 A and fixed Ii at 500 A (10 × In) means no adjustment dials — the overload and short-circuit thresholds are set at the factory. That simplifies ordering but locks the trip curve; if the downstream load changes, the breaker must be swapped, not re-set. The UVR coil drops the breaker on loss of control voltage (120–127 V AC). Common in safety circuits where a machine must power down on undervoltage or emergency-stop.