The Siemens 3VA1112-5MH36-0CC0 is a 3-pole IEC frame 160 molded-case circuit breaker with a 125 A rating and a 55 kA interrupting capacity at 415 V AC — class M breaking capacity, meaning it handles moderate fault levels typical of industrial distribution panels without cascading upstream. The TM120M thermal-magnetic trip unit provides starter protection: the thermal element tracks motor heating, while the magnetic short-circuit pickup is adjustable from 5 to 15 times In (625 A to 1875 A). This breaker ships without overload protection (the TM120M covers short-circuit only; motor overload protection must come from a separate relay or contactor).
What the ratings mean for fit
The 55 kA Icu at 415 V AC is the ultimate breaking capacity — the breaker can interrupt one fault at that level and remain functional, though not necessarily reusable. For selectivity studies, the Ics (service breaking capacity) is typically 100% of Icu on the 3VA1 platform, so downstream devices can coordinate without nuisance trips. The 125 A continuous rating suits motor branch circuits, feeder taps, or panel main breakers sized for that load. The undervoltage release (UVR) coil is wound for 120-127 V AC, 50/60 Hz — it will drop the breaker open when control voltage falls below about 70% of rated, a common requirement for emergency-stop circuits or undervoltage protection schemes.
Deployment context
This breaker mounts on a DIN rail or directly to a panel backplate via the 3VA1's integrated clip — no adapter needed. The clamp terminals accept copper or aluminum conductors up to 185 mm², typical for panel feeder connections. The two HQ auxiliary switches provide position feedback (open/closed) to a PLC or status lamp; the UVR coil occupies the left-side accessory slot. In a motor starter assembly, this breaker serves as the branch-circuit short-circuit protective device (SCPD) ahead of a contactor and overload relay.