What this breaker is and what it does
The Siemens 3VA1125-3GF42-0AA0-ZD00 is a 4-pole IEC frame 160 molded-case circuit breaker with a 25 A continuous rating (In=25A) and a breaking capacity class N — Icu=25 kA at 415 V. That 25 kA interrupting rating means it can safely clear a fault up to that level on a 415 V three-phase system without welding contacts or rupturing the case, which is the standard for downstream distribution panels and motor branch circuits in IEC markets.
Adjustable protection and what it means on the line
Overload protection (Ir) is adjustable from 18 A to 25 A via the TM240 thermal-magnetic trip unit — you dial it to match the actual load current, not the breaker frame. Short-circuit magnetic pickup (Ii) is set at 6.4 to 12.8 times In, which for a 25 A breaker means the instantaneous trip point ranges from 160 A to 320 A. That range lets you coordinate with downstream devices: set low for sensitive loads (e.g., control transformers), set high to ride through motor inrush on a conveyor or pump start.
Where it fits in the panel
This breaker mounts on a standard DIN rail in the enclosure. The 100% N-conductor protection means the neutral pole is fully rated and protected — no derating needed for single-phase line-to-neutral faults. The nut keeper kit is included for DC Power OEM applications in China, so if you're building a DC bus distribution panel, the hardware for secure bus-bar connections is already in the box.