The Siemens 3VA1112-5MH32-0HA0 is a 3-pole IEC frame 160 circuit breaker rated 125 A continuous with a breaking capacity Icu of 55 kA at 415 V AC. That 55 kA rating means it can safely interrupt a fault current up to that level without welding or rupturing — critical for high-fault panels downstream of a large transformer. The TM120M thermal-magnetic trip unit is set for starter protection: the thermal element tracks motor heating, and the magnetic pickup is adjustable 5–15 x In, so you set it just above the motor's locked-rotor inrush without nuisance tripping on start.
This breaker ships with a shunt trip (STL) coil rated 12–30 V DC or 24 V AC 50/60 Hz — a remote-trip input for emergency-stop or PLC-driven shutdown. The nut keeper kit is included, which prevents the terminal screws from backing out under vibration on a panel door or machine-mounted enclosure. No overload relay is built in; this is a magnetic-only short-circuit protector paired with an external overload (the 'AM' designation), so the motor's thermal protection is handled separately, typically by a Siemens 3RU2 or similar block.