What this breaker is and what the ratings mean
The Siemens 3VM1112-3ED36-0AA2 is a 3-pole IEC frame 160 molded-case circuit breaker rated for line protection. The 25 kA breaking capacity at 415 V (Icu) means it can safely interrupt a fault current up to that level without failing — that is the class N rating, which covers most commercial and light industrial distribution panels where the available fault current stays under 25 kA. The fixed thermal overload setting (Ir = 125 A, non-adjustable) and fixed short-circuit pickup (Ii = 10 x In = 1250 A) make this a straightforward drop-in for a 125 A feeder or branch circuit where coordination studies already fix the trip thresholds.