What this part is and what it does
The Siemens 3VM1112-3ED26-0AA2 is a 2-pole IEC frame 160 molded-case circuit breaker from the 3VM1 series, rated for line protection with a TM210 thermal-magnetic trip unit. It is set at In=125A with a fixed overload Ir=125A and a non-adjustable short-circuit pickup Ii=10 x In, so the magnetic trip fires at 1250 A. The breaking capacity is Icu=25kA at 415 V AC, which is the class N level — sufficient for most downstream distribution panels in commercial and light industrial buildings where fault currents stay under that threshold. The 25 kA @ 415 V rating means this breaker can safely interrupt a bolted fault up to that current without welding contacts or rupturing the case. In a typical 400/415 V three-phase panel, that covers the majority of secondary-distribution scenarios. The fixed Ir (no adjustment dial) simplifies ordering — what you see on the nameplate is what you get in the panel — but also means you cannot dial it down for a lightly loaded feeder; select the exact 125 A rating for the load.
Panel integration and wiring
Terminal connection type is listed as standard screw-clamp terminals, sized for the 125 A continuous current. The 2-pole format occupies two module widths on a DIN rail or panel-mount base. When installing, maintain the manufacturer's recommended bending radius for the incoming cable and leave enough gland-plate space for the outgoing conductors — at 125 A you are likely running 35 mm² or 50 mm² copper, which needs generous bend space inside the enclosure.