What this breaker is and what the ratings mean
The Siemens 3VA1125-4ED42-0AA0-ZD00 is a 4-pole IEC frame 160 molded-case circuit breaker with a 25 A fixed thermal-magnetic trip (TM210, FTFM). The 36 kA breaking capacity at 415 V (class S) tells you it can safely interrupt a fault current up to that level without welding contacts or cascading upstream — that's the number that governs selectivity coordination in a distribution panel. The short-circuit protection is fixed at 12.8 × In (320 A magnetic pickup), so it's sized for general line protection, not motor starting where you'd want a higher multiple to avoid nuisance trips on inrush.
Deployment context
This breaker mounts in a standard IEC distribution panel or enclosure. The N conductor is unprotected (straight-through), and the nut keeper kit is included for DC Power OEM builds in China — that's a specific mechanical fit for that assembly line. The 4-pole configuration with a solid-neutral path means it's suited for 3-phase + N systems where you want overcurrent protection on the phases only.