What this MCCB carries and where it fits
The Siemens 3VA1112-5GD46-0AA0 is a SENTRON molded case circuit breaker rated for 125 A continuous current with a TM210 thermal-magnetic release. The 4-pole construction handles three-phase plus neutral, and the 100% N-conductor protection design means the neutral pole is rated for full phase current — no derating needed on the fourth pole. Interrupting capacity hits 187 kA at 240 V, dropping to 121 kA at 415 V and 75.6 kA at 440 V. At 500 V and 690 V it still holds 17 kA. That kind of headroom on a 125 A frame means this breaker clears high-fault conditions without cascading upstream — useful in transformer secondaries or large motor control centers where available fault current runs high. The thermal-magnetic release (TM210) gives adjustable thermal pickup and fixed magnetic trip. The magnetic short-circuit pickup is adjustable up to 1,250 A (10× In), letting you tune it for motor inrush or transformer energization without nuisance trips. The TM designation means no electronic trip unit — simpler, more robust in vibration-heavy environments like wind turbine nacelles or compressor skids.
Thermal derating — real-world current capability
The 125 A rating holds up to 50 °C ambient. Above that, the breaker derates linearly: 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. If your panel runs hot — say a sealed enclosure with drives or transformers — this derating curve is what you size against, not the nameplate 125 A. The maximum operating temperature is 70 °C; storage range spans -40 °C to 80 °C.
Physical fit and panel integration
Dimensions are 70 mm deep, 101.6 mm wide (4 inches), and 130 mm tall. The 4-inch width is standard for a 4-pole MCCB on a DIN rail or panel-mount base. The front face carries IP40 protection — fine for a dry indoor panel, but not for washdown or outdoor exposure without an enclosure. The optional motor drive (listed as available) allows remote tripping or resetting, which is useful in automated lines or wind turbine pitch cabinets where access is limited.
Approvals and compliance
Rated insulation voltage is 800 V AC; max operational voltage with DC is 600 V. The reference code per IEC 81346-2 is Q (switching device). The part carries Siemens' standard compliance documentation for RoHS, REACH, UL, and IEC — the specific certs are listed in the manufacturer's declaration, which is available on request. No ground-fault monitoring is built in; that's handled externally if needed.