125 A MCCB with TM210 release — selectivity and SCCR headroom
The Siemens 3VA1112-3FD42-0AA0 is a SENTRON molded case circuit breaker rated for 125 A continuous at 40 °C, with the TM210 thermal-magnetic release. The 4-pole design handles three-phase plus neutral protection, and the 50% N-conductor protection setting means the neutral pole trips at half the phase rating — standard for distribution panels where the neutral carries only unbalanced load. Breaking capacity is the headline selector here: 75.6 kA at 240 V AC, 52.5 kA at 415 V AC, 32 kA at 440 V AC, and 11.9 kA at both 500 V and 690 V AC. For a site electrical engineer building a selective coordination study, the 415 V figure is the one that governs most European industrial panels — 52.5 kA SCCR gives headroom above typical 25–36 kA fault levels at the main distribution board. Rated insulation voltage is 800 V, and the operating voltage goes to 690 V AC, so this breaker is suited for 400/480 V systems with margin for voltage swells. The IP40 front protection means it's enclosed in a panel — not for washdown environments, but standard for switchgear cubicles.
Thermal derating and power loss
The continuous current holds flat at 125 A from 40 °C through 50 °C, then derates to 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. For a panel with ambient near the upper limit, the 70 °C figure is the one to size against — 114 A continuous, not 125 A. Maximum power loss is 28.1 W, which matters for enclosure thermal calculations when grouping multiple breakers. Storage temperature range is -40 °C to 80 °C; operating range is -25 °C to 70 °C. The storage limit governs handling and warehousing, not running conditions.
Dimensions and panel fit
Dimensions are 130 mm height, 101.6 mm width, 70 mm depth. The 70 mm depth is the dimension that matters for shallow enclosure clearance — standard 200 mm deep enclosures have no issue, but retrofit into older 150 mm deep panels requires checking the wiring bend radius behind the breaker.