What this breaker carries
The Siemens 3VA1112-5MH32-0JC0 is a 3-pole IEC circuit breaker in the 3VA1 frame-160 platform, rated 125 A continuous with a 55 kA interrupting capacity at 415 V AC (class M). That interrupting figure means it can clear a bolted fault up to 55 kA without welding its contacts or venting arc gas into the panel — critical for downstream selectivity in a distribution board or motor control center where the upstream transformer can deliver that kind of fault current. It ships with a TM120M thermal-magnetic trip unit set for starter protection — magnetic pickup adjustable 5–15× In (625–1875 A), no overload function (the motor starter handles that). The shunt trip (STL) coil accepts 110–127 V DC or AC 50/60 Hz, so a remote emergency-stop or fire-alarm contact can drop the breaker without walking to the panel. Two auxiliary switches (HQ) report position back to the PLC or status lamp.
Panel fit and integration
Mounts on a standard DIN rail in the enclosure. The nut keeper kit (included) holds the terminal screws captive during wiring — saves dropping hardware into a live panel. The shunt trip occupies the left-side accessory slot; the two auxiliary switches fit the right-side slot. No extra wiring space needed beyond the standard 3VA1 footprint.