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. 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.
Dimensions are 70 mm deep, 101.6 mm wide (4 inches), and 130 mm tall. 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.
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.